# Testing Methodologies Standards for Clean Code
This document provides comprehensive coding standards specific to *Testing Methodologies* within the Clean Code paradigm. It aims to guide developers in writing effective, maintainable, and reliable tests, ensuring the robustness and quality of Clean Code applications. These standards are designed to be used both by developers and AI coding assistants.
## 1. Principles of Clean Code Testing
Clean Code testing is not just about verifying functionality; it's about creating a safety net that allows for confident refactoring, simplifies debugging, and ensures long-term maintainability. Tests should be readable, focused, and resilient to change.
### Why Test?
* **Maintainability:** Well-written tests act as documentation, illustrating the intended behavior of the code. They enable confident refactoring without fear of introducing regressions.
* **Reduced Debugging Time:** Targeted tests pinpoint the source of errors quickly, significantly reducing debugging efforts.
* **Quality Assurance:** Comprehensive testing increases confidence in the software's reliability and reduces the risk of defects reaching production.
* **Design Improvement:** The act of writing tests forces you to think about the design of your code, often leading to better, more decoupled designs.
## 2. Strategies for Unit, Integration, and E2E Testing in Clean Code
A robust testing strategy requires a tiered approach that encompasses unit, integration, and end-to-end (E2E) testing.
### 2.1 Unit Testing
Unit tests focus on the smallest testable parts of the application – usually individual functions or classes.
* **Standard:** Isolate units of code and verify their behavior in isolation. Use mocks, stubs, and test doubles to control dependencies.
* **Do This:** Write focused unit tests that target a single, well-defined function or method.
* **Don't Do This:** Create brittle tests that are tightly coupled to the implementation details, making refactoring difficult. Do not write tests that have side effects.
* **Why:** Isolating the unit allows for quick identification of bugs and reduces the scope of investigation.
"""python
# Example: Unit test for a simple function
import unittest
from my_module import add
class TestAddFunction(unittest.TestCase):
def test_add_positive_numbers(self):
self.assertEqual(add(2, 3), 5)
def test_add_negative_numbers(self):
self.assertEqual(add(-2, -3), -5)
def test_add_mixed_numbers(self):
self.assertEqual(add(2, -3), -1)
def test_add_zero(self):
self.assertEqual(add(2, 0), 2)
if __name__ == '__main__':
unittest.main()
"""
* **Modern Approach:** Leverage test-driven development (TDD) where you write the test before writing the code. This helps to design testable and well-defined units of code.
* **Standard:** Apply the FIRST principles of unit testing: Fast, Independent, Repeatable, Self-Validating, Timely.
* **Do This:** Ensure tests are fast to execute, independent of each other, repeatable in any environment, self-validating with clear pass/fail results, and written promptly after the code.
* **Don't Do This:** Create slow, dependent tests that are prone to failures in different environments or that require manual inspection to determine the result.
* **Why:** FIRST principles promote maintainable, reliable, and efficient unit tests.
* **Standard:** Aim for high code coverage with meaningful assertions tailored to the expected behavior of the unit.
* **Do This:** Write tests that exercise all branches of code and assert the correct output for various inputs, including edge cases and invalid inputs. Use coverage tools to identify untested code paths.
* **Don't Do This:** Blindly aim for 100% coverage without considering the quality of assertions and the meaningfulness of the tests.
* **Why:** High code coverage, when combined with well-written assertions, provides assurance that the code behaves as expected.
"""python
# Example using pytest and code coverage
# Install pytest and pytest-cov: pip install pytest pytest-cov
# Run tests and generate coverage report: pytest --cov=my_module
import pytest
from my_module import divide
def test_divide_positive_numbers():
assert divide(10, 2) == 5
def test_divide_by_zero():
with pytest.raises(ValueError):
divide(10, 0) # Expecting ValueError
"""
### 2.2 Integration Testing
Integration tests verify the interactions between different units or components of the application.
* **Standard:** Focus on testing the interactions between modules and subsystems. Use real dependencies where practical or controlled test environments.
* **Do This:** Write integration tests to verify that different parts of the system work correctly together, such as a service interacting with a database or an API communicating with other services.
* **Don't Do This:** Try to test entire system workflows as unit tests. Over-mocking in integration tests can obscure real integration issues.
* **Why:** Integration tests ensure that the individual units function correctly as a cohesive system.
"""python
# Example: Integration test for a service that interacts with a database
import unittest
from unittest.mock import patch
from service import UserService
from database import DatabaseConnection
class TestUserServiceIntegration(unittest.TestCase):
@patch('database.DatabaseConnection.get_user')
def test_get_user_successful(self, mock_get_user):
mock_get_user.return_value = {'id': 1, 'name': 'Test User'}
user_service = UserService(DatabaseConnection())
user = user_service.get_user(1)
self.assertEqual(user['name'], 'Test User')
if __name__ == '__main__':
unittest.main()
"""
* **Standard:** Employ contract testing to verify that APIs conform to their documented specifications.
* **Do This:** Define clear API contracts using standards like OpenAPI/Swagger and employ tools to automatically generate integration tests based on them.
* **Don't Do This:** Neglect proper API contract management and rely on ad-hoc testing, leading to integration issues and inconsistencies.
* **Why:** Contract testing enables independent development and deployment of services, reducing the risk of integration failures.
* **Standard:** Write integration tests that cover different scenarios, including successful interactions, error handling, and edge cases.
* **Do This:** Simulate various real-world conditions and verify that the system behaves correctly under stress, with unexpected inputs, or during network disruptions.
* **Don't Do This:** Only test happy paths and ignore potential failure scenarios.
* **Why:** Comprehensive integration testing ensures system reliability and fault tolerance.
### 2.3 End-to-End (E2E) Testing
E2E tests validate the entire application workflow, simulating real user interactions from start to finish.
* **Standard:** Simulate realistic user scenarios and verify that the application behaves as expected from the user's perspective.
* **Do This:** Write E2E tests that cover key user journeys, such as login, data input, processing, and output.
* **Don't Do This:** Focus on testing individual components in E2E tests. Over-reliance on UI-based E2E tests can lead to slow and brittle test suites.
* **Why:** E2E tests validate the complete system functionality and ensure a smooth user experience.
"""python
# Example using Selenium for E2E testing a web application (simplified)
from selenium import webdriver
from selenium.webdriver.common.by import By
def test_login_successful():
driver = webdriver.Chrome() # Or other browser driver
driver.get("http://localhost:8000/login") # Replace with your app's URL
username_field = driver.find_element(By.ID, "username")
password_field = driver.find_element(By.ID, "password")
login_button = driver.find_element(By.ID, "login-button")
username_field.send_keys("testuser")
password_field.send_keys("password123")
login_button.click()
assert driver.current_url == "http://localhost:8000/home" # Replace with your home URL
driver.quit()
"""
* **Standard:** Utilize a testing framework that allows you to write expressive and maintainable E2E tests.
* **Do This:** Consider tools like Selenium, Cypress, Playwright, or Puppeteer, which provide high-level APIs for interacting with the application and asserting results.
* **Don't Do This:** Write complex and unreadable E2E tests that are difficult to maintain and debug.
* **Why:** Expressive testing frameworks improve the clarity and maintainability of E2E tests.
* **Standard:** Balance the need for comprehensive E2E coverage with the performance and maintainability considerations.
* **Do This:** Prioritize key user workflows and focus on testing critical functionality with E2E tests. Complement E2E tests with unit and integration tests for lower-level details.
* **Don't Do This:** Attempt to cover every possible scenario with E2E tests, leading to slow and fragile test suites.
* **Why:** Balancing E2E tests with other testing strategies ensures comprehensive test coverage without sacrificing performance and maintainability.
## 3. Testing and Clean Code Principles
Applying Clean Code principles to testing improves the readability, maintainability, and reliability of the test suite.
### 3.1 Readability and Clarity
* **Standard:** Name test methods descriptively using a clear naming convention that indicates the functionality being tested and the expected outcome.
* **Do This:** Use names like "test_add_positive_numbers_returns_sum" or "test_user_login_successful" to clearly convey the purpose of the test.
* **Don't Do This:** Use vague or ambiguous names like "test_something" or "test_function".
* **Why:** Clear test names improve the readability and understandability of the test suite, making it easier to identify and fix issues.
* **Standard:** Structure tests using the Arrange-Act-Assert (AAA) pattern.
* **Do This:** Organize each test method into three sections: Arrange (set up the test environment), Act (execute the code being tested), and Assert (verify the expected outcome).
* **Don't Do This:** Mix the arrangement, action, and assertion code, making the test difficult to read and understand.
* **Why:** The AAA pattern provides a consistent and structured way to write tests, improving readability and maintainability.
"""python
# Example: Using AAA pattern
import unittest
from my_module import calculate_discount
class TestCalculateDiscount(unittest.TestCase):
def test_calculate_discount_valid_amount(self):
# Arrange
price = 100
discount_percentage = 10
# Act
discounted_price = calculate_discount(price, discount_percentage)
# Assert
self.assertEqual(discounted_price, 90)
"""
* **Standard:** Write tests that are easy to understand and follow. Use comments sparingly, focusing instead on writing self-documenting code.
* **Do This:** Use clear and concise variable names, method names, and assertions that explain the test's purpose.
* **Don't Do This:** Write complex or convoluted tests that are difficult to understand without extensive comments.
* **Why:** Readable tests reduce the cognitive load required to understand and maintain the test suite.
### 3.2 Test Isolation and Dependencies
* **Standard:** Minimize dependencies in tests and isolate the unit being tested from external influences.
* **Do This:** Use mocks, stubs, and test doubles to control dependencies and simulate external services or data sources.
* **Don't Do This:** Rely on real dependencies that can introduce variability and make tests slow and unreliable.
* **Why:** Isolating tests ensures that they are repeatable and independent of external factors.
* **Standard:** Avoid shared state between tests to prevent unintended interactions and ensure test independence.
* **Do This:** Set up and tear down the test environment for each test method to ensure a clean slate.
* **Don't Do This:** Use global variables or shared resources that can be modified by different tests, leading to unpredictable results.
* **Why:** Test isolation prevents interference and ensures that each test is independent and repeatable.
"""python
# Example: Using setUp and tearDown for test isolation
import unittest
import tempfile
import os
class TestFileProcessing(unittest.TestCase):
def setUp(self):
# Create a temporary file for each test
self.temp_file = tempfile.NamedTemporaryFile(delete=False)
self.file_path = self.temp_file.name
def tearDown(self):
# Delete the temporary file after each test
self.temp_file.close()
os.unlink(self.file_path)
def test_write_to_file(self):
with open(self.file_path, 'w') as f:
f.write("Test data")
with open(self.file_path, 'r') as f:
content = f.read()
self.assertEqual(content, "Test data")
"""
### 3.3 Refactoring and Maintainability
* **Standard:** Treat tests as first-class citizens in the codebase and apply the same Clean Code principles to them as you would to production code.
* **Do This:** Refactor tests regularly to improve readability, remove duplication, and ensure they remain relevant.
* **Don't Do This:** Neglect tests and allow them to become outdated, unreadable, or brittle.
* **Why:** Well-maintained tests provide a reliable safety net for refactoring the production code.
* **Standard:** Remove duplication in tests by using helper methods or test fixtures.
* **Do This:** Extract common setup or assertion code into reusable methods or test fixtures to reduce redundancy.
* **Don't Do This:** Duplicate code across multiple tests, making them harder to maintain and update.
* **Why:** Reducing duplication improves the maintainability and readability of the test suite.
### 3.4 Avoiding Anti-Patterns
* **Standard:** Avoid brittle tests that are tightly coupled to the implementation details of the code.
* **Do This:** Focus on testing the behavior of the code rather than its implementation. Use abstractions and interfaces to decouple tests from specific implementations.
* **Don't Do This:** Write tests that rely on specific class names, method names, or data structures, making them susceptible to breaking when the code is refactored (unless the refactoring changes the behavior, then the test should BREAK!).
* **Why:** Brittle tests are difficult to maintain and can hinder refactoring efforts.
* **Standard:** Avoid over-mocking or excessive use of test doubles, as it can lead to testing the mocks rather than the actual code.
* **Do This:** Use mocks and stubs judiciously to isolate dependencies and control external interactions.
* **Don't Do This:** Mock everything, leading to tests that are detached from reality and don't verify the actual behavior of the code.
* **Why:** Over-mocking can create a false sense of security and mask real integration problems.
## 4. Technology-Specific Considerations
Testing methodologies can vary depending on the programming language, framework, and tools being used.
### 4.1 Python
* **Testing Frameworks:** *pytest*, *unittest*
* **Mocking Libraries:** *unittest.mock*, *pytest-mock*
* **Code Coverage Tools:** *coverage.py*, *pytest-cov*
"""python
# Example: Using pytest fixtures to set up test environment
import pytest
from my_module import MyClass
@pytest.fixture
def my_object():
return MyClass()
def test_my_method(my_object):
result = my_object.my_method()
assert result == expected_value
"""
### 4.2 JavaScript/TypeScript
* **Testing Frameworks:** *Jest*, *Mocha*, *Jasmine*, *Vitest*
* **Assertion Libraries:** *Chai*, *expect.js*
* **Mocking Libraries:** *Sinon.JS*, *Jest mocks*
* **E2E Testing:** *Cypress*, *Playwright*, *Selenium*
"""typescript
// Example using Jest and TypeScript
import { myFunction } from './myModule';
describe('myFunction', () => {
it('should return the correct value', () => {
expect(myFunction(5)).toBe(10);
});
});
"""
### 4.3 Java
* **Testing Frameworks:** *JUnit*, *TestNG*
* **Mocking Libraries:** *Mockito*, *EasyMock*, *PowerMock*
* **Code Coverage Tools:** *JaCoCo*, *Cobertura*
"""java
// Example using JUnit and Mockito
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;
import static org.mockito.Mockito.*;
class MyClassTest {
@Test
void myMethodTest() {
MyDependency dependency = mock(MyDependency.class);
when(dependency.getValue()).thenReturn(5);
MyClass myObject = new MyClass(dependency);
int result = myObject.myMethod();
assertEquals(10, result);
}
}
"""
## 5. Conclusion
Adhering to these testing methodology standards for Clean Code will result in a more robust, maintainable, and reliable codebase. By writing clear, focused, and well-structured tests, developers can ensure that their code behaves as expected, making refactoring and debugging easier and reducing the risk of introducing bugs. These guidelines facilitate a culture of quality, encouraging the development of high-quality software that meets the needs of its users. Remember that testing is an integral part of the development process, not an afterthought. By embracing these principles, developers can ensure the long-term health and success of their Clean Code projects.
danielsogl
Created Mar 6, 2025
This guide explains how to effectively use .clinerules with Cline, the AI-powered coding assistant.
The .clinerules file is a powerful configuration file that helps Cline understand your project's requirements, coding standards, and constraints. When placed in your project's root directory, it automatically guides Cline's behavior and ensures consistency across your codebase.
Place the .clinerules file in your project's root directory. Cline automatically detects and follows these rules for all files within the project.
# Project Overview project: name: 'Your Project Name' description: 'Brief project description' stack: - technology: 'Framework/Language' version: 'X.Y.Z' - technology: 'Database' version: 'X.Y.Z'
# Code Standards standards: style: - 'Use consistent indentation (2 spaces)' - 'Follow language-specific naming conventions' documentation: - 'Include JSDoc comments for all functions' - 'Maintain up-to-date README files' testing: - 'Write unit tests for all new features' - 'Maintain minimum 80% code coverage'
# Security Guidelines security: authentication: - 'Implement proper token validation' - 'Use environment variables for secrets' dataProtection: - 'Sanitize all user inputs' - 'Implement proper error handling'
Be Specific
Maintain Organization
Regular Updates
# Common Patterns Example patterns: components: - pattern: 'Use functional components by default' - pattern: 'Implement error boundaries for component trees' stateManagement: - pattern: 'Use React Query for server state' - pattern: 'Implement proper loading states'
Commit the Rules
.clinerules in version controlTeam Collaboration
Rules Not Being Applied
Conflicting Rules
Performance Considerations
# Basic .clinerules Example project: name: 'Web Application' type: 'Next.js Frontend' standards: - 'Use TypeScript for all new code' - 'Follow React best practices' - 'Implement proper error handling' testing: unit: - 'Jest for unit tests' - 'React Testing Library for components' e2e: - 'Cypress for end-to-end testing' documentation: required: - 'README.md in each major directory' - 'JSDoc comments for public APIs' - 'Changelog updates for all changes'
# Advanced .clinerules Example project: name: 'Enterprise Application' compliance: - 'GDPR requirements' - 'WCAG 2.1 AA accessibility' architecture: patterns: - 'Clean Architecture principles' - 'Domain-Driven Design concepts' security: requirements: - 'OAuth 2.0 authentication' - 'Rate limiting on all APIs' - 'Input validation with Zod'
# Angular Guidelines Use this guidelines when working with Angular related code. ## 1. Core Architecture - **Standalone Components:** Components, directives, and pipes are standalone by default. The `standalone: true` flag is no longer required and should be omitted in new code (Angular v17+ and above). - **Strong Typing:** TypeScript types, interfaces, and models provide type safety throughout the codebase - **Single Responsibility:** Each component and service has a single, well-defined responsibility - **Rule of One:** Files focus on a single concept or functionality - **Reactive State:** Signals provide reactive and efficient state management - **Dependency Injection:** Angular's DI system manages service instances - **Function-Based DI:** Use function-based dependency injection with the `inject()` function instead of constructor-based injection in all new code. Example: ```typescript import { inject } from "@angular/core"; import { HttpClient } from "@angular/common/http"; export class MyService { private readonly http = inject(HttpClient); // ... } ``` - **Lazy Loading:** Deferrable Views and route-level lazy loading with `loadComponent` improve performance - **Directive Composition:** The Directive Composition API enables reusable component behavior - **Standalone APIs Only:** Do not use NgModules, CommonModule, or RouterModule. Import only required standalone features/components. - **No Legacy Modules:** Do not use or generate NgModules for new features. Migrate existing modules to standalone APIs when possible. ## 2. Angular Style Guide Patterns - **Code Size:** Files are limited to 400 lines of code - **Single Purpose Files:** Each file defines one entity (component, service, etc.) - **Naming Conventions:** Symbols have consistent, descriptive names - **Folder Structure:** Code is organized by feature-based folders - **File Separation:** Templates and styles exist in their own files for components - **Property Decoration:** Input and output properties have proper decoration - **Component Selectors:** Component selectors use custom prefixes and kebab-case (e.g., `app-feature-name`) - **No CommonModule or RouterModule Imports:** Do not import CommonModule or RouterModule in standalone components. Import only the required standalone components, directives, or pipes. ## 3. Input Signal Patterns - **Signal-Based Inputs:** The `input()` function creates InputSignals: ```typescript // Current pattern readonly value = input(0); // Creates InputSignal // Legacy pattern @Input() value = 0; ``` - **Required Inputs:** The `input.required()` function marks inputs as mandatory: ```typescript readonly value = input.required<number>(); ``` - **Input Transformations:** Transformations convert input values: ```typescript readonly disabled = input(false, { transform: booleanAttribute }); readonly value = input(0, { transform: numberAttribute }); ``` - **Two-Way Binding:** Model inputs enable two-way binding: ```typescript readonly value = model(0); // Creates a model input with change propagation // Model values update with .set() or .update() increment(): void { this.value.update(v => v + 1); } ``` - **Input Aliases:** Aliases provide alternative input names: ```typescript readonly value = input(0, { alias: "sliderValue" }); ``` ## 3a. Typed Reactive Forms - **Typed Forms:** Always use strictly typed reactive forms by defining an interface for the form values and using `FormGroup<MyFormType>`, `FormBuilder.group<MyFormType>()`, and `FormControl<T>()`. - **Non-Nullable Controls:** Prefer `nonNullable: true` for controls to avoid null issues and improve type safety. - **Patch and Get Values:** Use `patchValue` and `getRawValue()` to work with typed form values. - **Reference:** See the [Angular Typed Forms documentation](https://angular.dev/guide/forms/typed-forms) for details and examples. ## 4. Component Patterns - **Naming Pattern:** Components follow consistent naming - `feature.type.ts` (e.g., `hero-list.component.ts`) - **Template Extraction:** Non-trivial templates exist in separate `.html` files - **Style Extraction:** Styles exist in separate `.css/.scss` files - **Signal-Based Inputs:** Components use the `input()` function for inputs - **Two-Way Binding:** Components use the `model()` function for two-way binding - **Lifecycle Hooks:** Components implement appropriate lifecycle hook interfaces (OnInit, OnDestroy, etc.) - **Element Selectors:** Components use element selectors (`selector: 'app-hero-detail'`) - **Logic Delegation:** Services contain complex logic - **Input Initialization:** Inputs have default values or are marked as required - **Lazy Loading:** The `@defer` directive loads heavy components or features - **Error Handling:** Try-catch blocks handle errors - **Modern Control Flow:** Templates use `@if`, `@for`, `@switch` instead of structural directives - **State Representation:** Components implement loading and error states - **Derived State:** The `computed()` function calculates derived state - **No NgModules:** Do not use or reference NgModules in new code. ## 5. Styling Patterns - **Component Encapsulation:** Components use scoped styles with proper encapsulation - **CSS Methodology:** BEM methodology guides CSS class naming when not using Angular Material - **Component Libraries:** Angular Material or other component libraries provide consistent UI elements - **Theming:** Color systems and theming enable consistent visual design - **Accessibility:** Components follow a11y standards - **Dark Mode:** Components support dark mode where appropriate ## 5a. Angular Material and Angular CDK Usage - **Standard UI Library:** Use Angular Material v3 for all standard UI components (buttons, forms, navigation, dialogs, etc.) to ensure consistency, accessibility, and alignment with Angular best practices. - **Component Development:** Build new UI components and features using Angular Material components as the foundation. Only create custom components when Material does not provide a suitable solution. - **Behavioral Primitives:** Use Angular CDK for advanced behaviors (drag-and-drop, overlays, accessibility, virtual scrolling, etc.) and for building custom components that require low-level primitives. - **Theming:** Leverage Angular Material's theming system for consistent color schemes, dark mode support, and branding. Define and use custom themes in `styles.scss` or feature-level styles as needed. - **Accessibility:** All UI components must meet accessibility (a11y) standards. Prefer Material components for built-in a11y support. When using CDK or custom components, follow WCAG and ARIA guidelines. - **Best Practices:** - Prefer Material's layout and typography utilities for spacing and text. - Use Material icons and fonts for visual consistency. - Avoid mixing multiple UI libraries in the same project. - Reference the [Angular Material documentation](https://material.angular.io) for usage patterns and updates. - **CDK Utilities:** Use Angular CDK utilities for custom behaviors, overlays, accessibility, and testing harnesses. - **Migration:** For legacy or custom components, migrate to Angular Material/CDK where feasible. ## 5b. Template Patterns - **Modern Control Flow:** Use the new Angular control flow syntax: `@if`, `@for`, `@switch` in templates. Do not use legacy structural directives such as `*ngIf`, `*ngFor`, or `*ngSwitch`. - **No Legacy Structural Directives:** Remove or migrate any usage of `*ngIf`, `*ngFor`, or `*ngSwitch` to the new control flow syntax in all new code. Legacy code should be migrated when touched. - **Referencing Conditional Results:** When using `@if`, reference the result using the `as` keyword, e.g. `@if (user(); as u) { ... }`. This is the recommended pattern for accessing the value inside the block. See the [Angular documentation](https://angular.dev/guide/templates/control-flow#referencing-the-conditional-expressions-result) for details. ## 6. Service and DI Patterns - **Service Declaration:** Services use the `@Injectable()` decorator with `providedIn: 'root'` for singletons - **Data Services:** Data services handle API calls and data operations - **Error Handling:** Services include error handling - **DI Hierarchy:** Services follow the Angular DI hierarchy - **Service Contracts:** Interfaces define service contracts - **Focused Responsibilities:** Services focus on specific tasks - **Function-Based DI:** Use function-based dependency injection with the `inject()` function instead of constructor-based injection in all new code. Example: ```typescript import { inject } from "@angular/core"; import { HttpClient } from "@angular/common/http"; export class MyService { private readonly http = inject(HttpClient); // ... } ``` ## 7. Directive and Pipe Patterns - **Attribute Directives:** Directives handle presentation logic without templates - **Host Property:** The `host` property manages bindings and listeners: ```typescript @Directive({ selector: '[appHighlight]', host: { // Host bindings '[class.highlighted]': 'isHighlighted', '[style.color]': 'highlightColor', // Host listeners '(click)': 'onClick($event)', '(mouseenter)': 'onMouseEnter()', '(mouseleave)': 'onMouseLeave()', // Static properties 'role': 'button', '[attr.aria-label]': 'ariaLabel' } }) ``` - **Selector Prefixes:** Directive selectors use custom prefixes - **Pure Pipes:** Pipes are pure when possible for better performance - **Pipe Naming:** Pipes follow camelCase naming conventions ## 8. State Management Patterns - **Signals:** Signals serve as the primary state management solution - **Component Inputs:** Signal inputs with `input()` handle component inputs - **Two-Way Binding:** Model inputs with `model()` enable two-way binding - **Local State:** Writable signals with `signal()` manage local component state - **Derived State:** Computed signals with `computed()` calculate derived state - **Side Effects:** The `effect()` function handles side effects - **Error Handling:** Signal computations include error handling - **Signal Conversion:** The `toSignal()` and `toObservable()` functions enable interoperability with RxJS ## 9. Testing Patterns - **Test Coverage:** Tests cover components and services - **Unit Tests:** Focused unit tests verify services, pipes, and components - **Component Testing:** TestBed and component harnesses test components - **Mocking:** Tests use mocking techniques for dependencies - **Test Organization:** Tests follow the AAA pattern (Arrange, Act, Assert) - **Test Naming:** Tests have descriptive names that explain the expected behavior - **Playwright Usage:** Playwright handles E2E testing with fixtures and test isolation - **Test Environment:** Test environments match production as closely as possible ## 10. Performance Patterns - **Change Detection:** Components use OnPush change detection strategy - **Lazy Loading:** Routes and components load lazily - **Virtual Scrolling:** Virtual scrolling renders long lists efficiently - **Memoization:** Memoization optimizes expensive computations - **Bundle Size:** Bundle size monitoring and optimization reduce load times - **Server-Side Rendering:** SSR improves initial load performance - **Web Workers:** Web workers handle intensive operations ## 11. Security Patterns - **XSS Prevention:** User input undergoes sanitization - **CSRF Protection:** CSRF tokens secure forms - **Content Security Policy:** CSP headers restrict content sources - **Authentication:** Secure authentication protects user accounts - **Authorization:** Authorization checks control access - **Sensitive Data:** Client-side code excludes sensitive data ## 12. Accessibility Patterns - **ARIA Attributes:** ARIA attributes enhance accessibility - **Keyboard Navigation:** Interactive elements support keyboard access - **Color Contrast:** UI elements maintain proper color contrast ratios - **Screen Readers:** Components work with screen readers - **Focus Management:** Focus management guides user interaction - **Alternative Text:** Images include alt text
Add as custom prompt to Roocode you can completely replace the system prompt for this mode (aside from the role definition and custom instructions) by creating a file at .roo/system-prompt-codershortrules in your workspace. You are Roo, a highly skilled software engineer with extensive knowledge in many programming languages, frameworks, design patterns, and best practices. Use tools one at a time to complete tasks step-by-step. Wait for user confirmation after each tool use. Tools read_file: Read file contents. Use for analyzing code, text files, or configs. Output includes line numbers. Extracts text from PDFs and DOCX. Not for other binary files. Parameters: path (required) search_files: Search files in a directory using regex. Shows matches with context. Useful for finding code patterns or specific content. Parameters: path (required), regex (required), file_pattern (optional) list_files: List files and directories. Can be recursive. Don’t use to check if files you created exist; user will confirm. Parameters: path (required), recursive (optional) list_code_definition_names: List top-level code definitions (classes, functions, etc.) in a directory. Helps understand codebase structure. Parameters: path (required) apply_diff: Replace code in a file using a search and replace block. Must match existing content exactly. Use read_file first if unsure. Parameters: path (required), diff (required), start_line (required), end_line (required) Diff Format: text Wrap Copy <<<<<<< SEARCH [exact content] ======= [new content] >>>>>>> REPLACE write_to_file: Write full content to a file. Overwrites if exists, creates if not. MUST provide COMPLETE file content, not partial updates. MUST include app 3 parameters, path, content, and line_count Parameters: path (required), content (required), line_count (required) execute_command: Run CLI commands. Explain what the command does. Prefer complex commands over scripts. Commands run in the current directory. To run in a different directory, use cd path && command. Parameters: command (required) ask_followup_question: Ask the user a question to get more information. Use when you need clarification or details. Parameters: question (required) attempt_completion: Present the task result to the user. Optionally provide a CLI command to demo the result. Don’t use it until previous tool uses are confirmed successful. Parameters: result (required), command (optional) Tool Use Formatting IMPORTANT REPLACE tool_name with the tool you want to use, for example read_file. IMPORTANT REPLACE parameter_name with the parameter name, for example path. Format tool use with XML tags, e.g.: text Wrap Copy value1 value2 Guidelines Choose the right tool for the task. Use one tool at a time. Format tool use correctly. Wait for user confirmation after each tool use. Don’t assume tool success; wait for user feedback. Rules pass correct paths to tools. Don’t use ~ or $HOME. Tailor commands to the user's system. Prefer other editing tools over write_to_file for changes. Provide complete file content when using write_to_file. Don’t ask unnecessary questions; use tools to get information. Don’t be conversational; be direct and technical. Consider environment_details for context. ALWAYS replace tool_name, parameter_name, and parameter_value with actual values. Objective Break task into steps. Use tools to accomplish each step. Wait for user confirmation after each tool use. Use attempt_completion when task is complete.
# NgRx Signals Patterns This document outlines the state management patterns used in our Angular applications with NgRx Signals Store. ## 1. NgRx Signals Architecture - **Component-Centric Design:** Stores are designed around component requirements - **Hierarchical State:** State is organized in hierarchical structures - **Computed State:** Derived state uses computed values - **Declarative Updates:** State updates use patchState for immutability - **Store Composition:** Stores compose using features and providers - **Reactivity:** UIs build on automatic change detection - **Signal Interoperability:** Signals integrate with existing RxJS-based systems - **SignalMethod & RxMethod:** Use `signalMethod` for lightweight, signal-driven side effects; use `rxMethod` for Observable-based side effects and RxJS integration. When a service returns an Observable, always use `rxMethod` for side effects instead of converting to Promise or using async/await. ## 2. Signal Store Structure - **Store Creation:** The `signalStore` function creates stores - **Protected State:** Signal Store state is protected by default (`{ protectedState: true }`) - **State Definition:** Initial state shape is defined with `withState<StateType>({...})` - Root level state is always an object: `withState({ users: [], count: 0 })` - Arrays are contained within objects: `withState({ items: [] })` - **Dependency Injection:** Stores are injectable with `{ providedIn: 'root' }` or feature/component providers - **Store Features:** Built-in features (`withEntities`, `withHooks`, `signalStoreFeature`) handle cross-cutting concerns and enable store composition - **State Interface:** State interfaces provide strong typing - **Private Members:** Prefix all internal state, computed signals, and methods with an underscore (`_`). Ensure unique member names across state, computed, and methods. ```typescript withState({ count: 0, _internalCount: 0 }); withComputed(({ count, _internalCount }) => ({ doubleCount: computed(() => count() * 2), _doubleInternal: computed(() => _internalCount() * 2), })); ``` - **Member Integrity:** Store members have unique names across state, computed, and methods - **Initialization:** State initializes with meaningful defaults - **Collection Management:** The `withEntities` feature manages collections. Prefer atomic entity operations (`addEntity`, `updateEntity`, `removeEntity`, `setAllEntities`) over bulk state updates. Use `entityConfig` and `selectId` for entity identification. - **Entity Adapter Configuration:** Use `entityConfig` to configure the entity adapter for each store. Always specify the `entity` type, `collection` name, and a `selectId` function for unique entity identification. Pass the config to `withEntities<T>(entityConfig)` for strong typing and consistent entity management. ```typescript const userEntityConfig = entityConfig({ entity: type<User>(), collection: "users", selectId: (user: User) => user.id, }); export const UserStore = signalStore( { providedIn: "root" }, withState(initialState), withEntities(userEntityConfig), // ... ); ``` - **Custom Store Properties:** Use `withProps` to add static properties, observables, and dependencies. Expose observables with `toObservable`. ```typescript // Signal store structure example import { signalStore, withState, withComputed, withMethods, patchState, type, } from "@ngrx/signals"; import { withEntities, entityConfig } from "@ngrx/signals/entities"; import { computed, inject } from "@angular/core"; import { UserService } from "./user.service"; import { User } from "./user.model"; import { setAllEntities } from "@ngrx/signals/entities"; export interface UserState { selectedUserId: string | null; loading: boolean; error: string | null; } const initialState: UserState = { selectedUserId: null, loading: false, error: null, }; const userEntityConfig = entityConfig({ entity: type<User>(), collection: "users", selectId: (user: User) => user.id, }); export const UserStore = signalStore( { providedIn: "root" }, withState(initialState), withEntities(userEntityConfig), withComputed(({ usersEntities, usersEntityMap, selectedUserId }) => ({ selectedUser: computed(() => { const id = selectedUserId(); return id ? usersEntityMap()[id] : undefined; }), totalUserCount: computed(() => usersEntities().length), })), withMethods((store, userService = inject(UserService)) => ({ loadUsers: rxMethod<void>( pipe( switchMap(() => { patchState(store, { loading: true, error: null }); return userService.getUsers().pipe( tapResponse({ next: (users) => patchState(store, setAllEntities(users, userEntityConfig), { loading: false, }), error: () => patchState(store, { loading: false, error: "Failed to load users", }), }), ); }), ), ), selectUser(userId: string | null): void { patchState(store, { selectedUserId: userId }); }, })), ); ``` ## 3. Signal Store Methods - **Method Definition:** Methods are defined within `withMethods` - **Dependency Injection:** The `inject()` function accesses services within `withMethods` - **Method Organization:** Methods are grouped by domain functionality - **Method Naming:** Methods have clear, action-oriented names - **State Updates:** `patchState(store, newStateSlice)` or `patchState(store, (currentState) => newStateSlice)` updates state immutably - **Async Operations:** Methods handle async operations and update loading/error states - **Computed Properties:** `withComputed` defines derived state - **RxJS Integration:** `rxMethod` integrates RxJS streams. Use `rxMethod` for all store methods that interact with Observable-based APIs or services. Avoid using async/await with Observables in store methods. ```typescript // Signal store method patterns import { signalStore, withState, withMethods, patchState } from "@ngrx/signals"; import { inject } from "@angular/core"; import { TodoService } from "./todo.service"; import { Todo } from "./todo.model"; export interface TodoState { todos: Todo[]; loading: boolean; } export const TodoStore = signalStore( { providedIn: "root" }, withState<TodoState>({ todos: [], loading: false }), withMethods((store, todoService = inject(TodoService)) => ({ addTodo(todo: Todo): void { patchState(store, (state) => ({ todos: [...state.todos, todo], })); }, loadTodosSimple: rxMethod<void>( pipe( switchMap(() => { patchState(store, { loading: true }); return todoService.getTodos().pipe( tapResponse({ next: (todos) => patchState(store, { todos, loading: false }), error: () => patchState(store, { loading: false }), }), ); }), ), ), })), ); ``` ## 4. Entity Management - **Entity Configuration:** Entity configurations include ID selectors - **Collection Operations:** Entity operations handle CRUD operations - **Entity Relationships:** Computed properties manage entity relationships - **Entity Updates:** Prefer atomic entity operations (`addEntity`, `updateEntity`, `removeEntity`, `setAllEntities`) over bulk state updates. Use `entityConfig` and `selectId` for entity identification. ```typescript // Entity management patterns const userEntityConfig = entityConfig({ entity: type<User>(), collection: "users", selectId: (user: User) => user.id, }); export const UserStore = signalStore( withEntities(userEntityConfig), withMethods((store) => ({ addUser: signalMethod<User>((user) => { patchState(store, addEntity(user, userEntityConfig)); }), updateUser: signalMethod<{ id: string; changes: Partial<User> }>( ({ id, changes }) => { patchState(store, updateEntity({ id, changes }, userEntityConfig)); }, ), removeUser: signalMethod<string>((id) => { patchState(store, removeEntity(id, userEntityConfig)); }), setUsers: signalMethod<User[]>((users) => { patchState(store, setAllEntities(users, userEntityConfig)); }), })), ); ``` ## 5. Component Integration ### Component State Access - **Signal Properties:** Components access signals directly in templates - **OnPush Strategy:** Signal-based components use OnPush change detection - **Store Injection:** Components inject store services with the `inject` function - **Default Values:** Signals have default values - **Computed Values:** Components derive computed values from signals - **Signal Effects:** Component effects handle side effects ```typescript // Component integration patterns @Component({ standalone: true, imports: [UserListComponent], template: ` @if (userStore.users().length > 0) { <app-user-list [users]="userStore.users()"></app-user-list> } @else { <p>No users loaded yet.</p> } <div>Selected user: {{ selectedUserName() }}</div> `, changeDetection: ChangeDetectionStrategy.OnPush, }) export class UsersContainerComponent implements OnInit { readonly userStore = inject(UserStore); selectedUserName = computed(() => { const user = this.userStore.selectedUser(); return user ? user.name : "None"; }); constructor() { effect(() => { const userId = this.userStore.selectedUserId(); if (userId) { console.log(`User selected: ${userId}`); } }); } ngOnInit() { this.userStore.loadUsers(); } } ``` ### Signal Store Hooks - **Lifecycle Hooks:** The `withHooks` feature adds lifecycle hooks to stores - **Initialization:** The `onInit` hook initializes stores - **Cleanup:** The `onDestroy` hook cleans up resources - **State Synchronization:** Hooks synchronize state between stores ```typescript // Signal store hooks patterns export const UserStore = signalStore( withState<UserState>({ /* initial state */ }), withMethods(/* store methods */), withHooks({ onInit: (store) => { // Initialize the store store.loadUsers(); // Return cleanup function if needed return () => { // Cleanup code }; }, }), ); ``` ## 6. Advanced Signal Patterns ### Signal Store Features - **Feature Creation:** The `signalStoreFeature` function creates reusable features - **Generic Feature Types:** Generic type parameters enhance feature reusability ```typescript function withMyFeature<T>(config: Config<T>) { return signalStoreFeature(/*...*/); } ``` - **Feature Composition:** Multiple features compose together - **Cross-Cutting Concerns:** Features handle logging, undo/redo, and other concerns - **State Slices:** Features define and manage specific state slices ```typescript // Signal store feature patterns export function withUserFeature() { return signalStoreFeature( withState<UserFeatureState>({ /* feature state */ }), withComputed((state) => ({ /* computed properties */ })), withMethods((store) => ({ /* methods */ })), ); } // Using the feature export const AppStore = signalStore( withUserFeature(), withOtherFeature(), withMethods((store) => ({ /* app-level methods */ })), ); ``` ### Signals and RxJS Integration - **Signal Conversion:** `toSignal()` and `toObservable()` convert between Signals and Observables - **Effects:** Angular's `effect()` function reacts to signal changes - **RxJS Method:** `rxMethod<T>(pipeline)` handles Observable-based side effects. Always prefer `rxMethod` for Observable-based service calls in stores. Do not convert Observables to Promises for store logic. - Accepts input values, Observables, or Signals - Manages subscription lifecycle automatically - **Reactive Patterns:** Signals combine with RxJS for complex asynchronous operations ```typescript // Signal and RxJS integration patterns import { signalStore, withState, withMethods, patchState } from "@ngrx/signals"; import { rxMethod } from "@ngrx/signals/rxjs-interop"; import { tapResponse } from "@ngrx/operators"; import { pipe, switchMap } from "rxjs"; import { inject } from "@angular/core"; import { HttpClient } from "@angular/common/http"; import { User } from "./user.model"; export interface UserState { users: User[]; loading: boolean; error: string | null; } export const UserStore = signalStore( { providedIn: "root" }, withState({ users: [], loading: false, error: null }), withMethods((store, http = inject(HttpClient)) => ({ loadUsers: rxMethod<void>( pipe( switchMap(() => { patchState(store, { loading: true, error: null }); return http.get<User[]>("/api/users").pipe( tapResponse({ next: (users) => patchState(store, { users, loading: false }), error: () => patchState(store, { loading: false, error: "Failed to load users", }), }), ); }), ), ), })), ); ``` ### Signal Method for Side Effects The `signalMethod` function manages side effects driven by Angular Signals within Signal Store: - **Input Flexibility:** The processor function accepts static values or Signals - **Automatic Cleanup:** The underlying effect cleans up when the store is destroyed - **Explicit Tracking:** Only the input signal passed to the processor function is tracked - **Lightweight:** Smaller bundle size compared to `rxMethod` ```typescript // Signal method patterns import { signalStore, withState, withMethods, patchState } from '@ngrx/signals'; import { signalMethod } from '@ngrx/signals'; import { inject } from '@angular/core'; import { Logger } from './logger'; interface UserPreferencesState { theme: 'light' | 'dark'; sendNotifications: boolean; const initialState: UserPreferencesState = { theme: 'light', sendNotifications: true, }; export const PreferencesStore = signalStore( { providedIn: 'root' }, withState(initialState), withProps(() => ({ logger: inject(Logger), })); withMethods((store) => ({ setSendNotifications(enabled: boolean): void { patchState(store, { sendNotifications: enabled }); }, // Signal method reacts to theme changes logThemeChange: signalMethod<'light' | 'dark'>((theme) => { store.logger.log(`Theme changed to: ${theme}`); }), setTheme(newTheme: 'light' | 'dark'): void { patchState(store, { theme: newTheme }); }, })), ); ``` ## 7. Custom Store Properties - **Custom Properties:** The `withProps` feature adds static properties, observables, and dependencies - **Observable Exposure:** `toObservable` within `withProps` exposes state as observables ```typescript withProps(({ isLoading }) => ({ isLoading$: toObservable(isLoading), })); ``` - **Dependency Grouping:** `withProps` groups dependencies for use across store features ```typescript withProps(() => ({ booksService: inject(BooksService), logger: inject(Logger), })); ``` ## 8. Project Organization ### Store Organization - **File Location:** Store definitions (`*.store.ts`) exist in dedicated files - **Naming Convention:** Stores follow the naming pattern `FeatureNameStore` - **Model Co-location:** State interfaces and models exist near store definitions - **Provider Functions:** Provider functions (`provideFeatureNameStore()`) encapsulate store providers ```typescript // Provider function pattern import { Provider } from "@angular/core"; import { UserStore } from "./user.store"; export function provideUserSignalStore(): Provider { return UserStore; } ``` ### Store Hierarchy - **Parent-Child Relationships:** Stores have clear relationships - **State Sharing:** Related components share state - **State Ownership:** Each state slice has a clear owner - **Store Composition:** Complex UIs compose multiple stores
# State Management Standards for Clean Code This document outlines coding standards for state management within Clean Code principles. It provides specific guidelines and examples to ensure code related to state is maintainable, readable, performant, and secure. These standards are designed to work with the latest recommended practices and features within the Clean Code ecosystem. ## 1. Principles of Clean State Management Clean state management is about structuring your application's data in a way that's predictable, manageable, and testable. It involves making state changes explicit, limiting side effects, and ensuring data consistency. Applying clean code principles to state enhances maintainability, reduces bugs, and improves collaborative development. * **Single Source of Truth:** Ensure each piece of data has one authoritative source. This prevents inconsistencies and simplifies debugging. * **Immutability:** Favor immutable data structures. Immutable data makes state changes more predictable and helps prevent unintended side effects. * **Explicit State Transitions:** State transitions should be clear and well-defined, making it easier to understand how the application evolves over time. * **Separation of Concerns:** Keep state management logic separate from UI components or business logic. This enhances modularity and testability. * **Minimal Global State:** Limit the use of global state. Widespread global state can make it difficult to track dependencies and lead to unexpected behavior. ## 2. Architectural Patterns for State Management Choosing the right architecture for state management depends on the complexity of the application. Here are a few common patterns and guidelines: ### 2.1 Local State Managing state within a single component should be a default option. You typically use local state for isolated functionalities that don't necessitate sharing state or reactivity beyond the component’s scope. * **Do This:** Use local state for isolated component features. * **Don't Do This:** Share local state directly between unrelated components. """javascript // Example React local state using useState import React, { useState } from 'react'; function Counter() { const [count, setCount] = useState(0); return ( <div> <p>Count: {count}</p> <button onClick={() => setCount(count + 1)}>Increment</button> </div> ); } """ ### 2.2 Redux Pattern (Centralized State) The Redux pattern emphasizes a single store for application state, using reducers to handle actions and state transitions immutably. * **Do This:** * Use Redux or similar libraries for complex, application-wide state. * Define actions as plain objects with a "type" field. * Use pure functions as reducers to ensure predictable state transitions. * Selectors should cache results to prevent unnecessary re-renders. * **Don't Do This:** * Mutate the state directly in reducers. * Perform asynchronous operations directly in reducers. * Overuse Redux for simple components with minimal state. """javascript // Example Redux setup // Action const INCREMENT = 'INCREMENT'; const DECREMENT = 'DECREMENT'; const increment = () => ({ type: INCREMENT }); const decrement = () => ({ type: DECREMENT }); // Reducer const initialState = { count: 0 }; const counterReducer = (state = initialState, action) => { switch (action.type) { case INCREMENT: return { ...state, count: state.count + 1 }; case DECREMENT: return { ...state, count: state.count - 1 }; default: return state; } }; // Store creation import { createStore } from 'redux'; const store = createStore(counterReducer); // Component integration (React example) import { useSelector, useDispatch } from 'react-redux'; function CounterComponent() { const count = useSelector(state => state.count); const dispatch = useDispatch(); return ( <div> <p>Count: {count}</p> <button onClick={() => dispatch(increment())}>Increment</button> <button onClick={() => dispatch(decrement())}>Decrement</button> </div> ); } """ ### 2.3 Context API (Scoped State) Context API provides a way to pass data through the component tree without having to pass props manually at every level. While it is simpler than Redux it is still intended for scenarios that benefit from shared state. * **Do This:** * Use Context API for theming, user authentication, or other application-wide configurations. * Use "useContext" hook to consume context values. * Combine Context API with "useReducer" for complex state logic. * **Don't Do This:** * Use Context API as a general replacement for prop drilling in scenarios where component composition is better suited. * Overuse Context API resulting in unnecessary re-renders. """javascript // Example Context API setup import React, { createContext, useContext, useState } from 'react'; // Create Context const ThemeContext = createContext(); // Context Provider function ThemeProvider({ children }) { const [theme, setTheme] = useState('light'); const toggleTheme = () => { setTheme(prevTheme => (prevTheme === 'light' ? 'dark' : 'light')); }; return ( <ThemeContext.Provider value={{ theme, toggleTheme }}> {children} </ThemeContext.Provider> ); } // Custom Hook to consume Context function useTheme() { return useContext(ThemeContext); } // Component using Context function ThemeToggler() { const { theme, toggleTheme } = useTheme(); return ( <button onClick={toggleTheme}> Toggle Theme (Current: {theme}) </button> ); } // Usage in App function App() { return ( <ThemeProvider> <div> <ThemeToggler /> </div> </ThemeProvider> ); } """ ### 2.4 Observable Pattern (Reactive State) The observable pattern, often implemented with libraries like RxJS, is used for handling asynchronous data streams and complex event-driven applications. * **Do This:** * Use RxJS or similar libraries for handling asynchronous data streams. * Structure application logic as a pipeline of observable transformations. * Use subjects to bridge different parts of the application. * **Don't Do This:** * Overuse RxJS for simple event handling. * Introduce memory leaks by not unsubscribing from observables. * Create overly complex observable chains that are hard to understand. """javascript // Example RxJS setup import { fromEvent, interval } from 'rxjs'; import { map, filter, scan, takeUntil } from 'rxjs/operators'; // Example: Click counter observable const button = document.getElementById('myButton'); const click$ = fromEvent(button, 'click'); const counter$ = click$.pipe( map(() => 1), scan((acc, value) => acc + value, 0) ); counter$.subscribe(count => { console.log("Button clicked ${count} times"); }); // Example: Auto-incrementing counter that stops after 5 seconds const interval$ = interval(1000); const stop$ = fromEvent(document.getElementById('stopButton'), 'click'); interval$.pipe( takeUntil(stop$) // Stop the interval when the stop button is clicked ).subscribe(val => console.log("Interval value: ${val}")); """ ### 2.5 State Machines State machines are useful for managing complex state transitions with clearly defined states and transitions. * **Do This:** * Use state machines for scenarios with clearly defined states and transitions. * Model state transitions explicitly, reducing possible unexpected states. * Ensure state machines are well-documented, especially for complex systems. * **Don't Do This:** * Overuse state machines for simple state management. * Create monolithic state machines that are difficult to understand. """javascript // Example: JavaScript state machine using XState import { createMachine, interpret } from 'xstate'; // Define the state machine const trafficLightMachine = createMachine({ id: 'trafficLight', initial: 'green', states: { green: { after: { 5000: 'yellow' // After 5 seconds, transition to yellow } }, yellow: { after: { 1000: 'red' // After 1 second, transition to red } }, red: { after: { 6000: 'green' // After 6 seconds, transition to green } } } }); // Interpret the state machine const trafficService = interpret(trafficLightMachine).start(); trafficService.onTransition(state => { console.log("Traffic light is now ${state.value}"); }); // Example usage (simulating events or external triggers) // trafficService.send('TIMER'); """ ## 3. Implementing Immutability Immutability ensures that once an object is created, its state cannot be changed. This helps prevent accidental state mutations, making it easier to track and manage state changes, which aids in debugging and improves performance in certain scenarios. * **Do This:** * Use immutable data structures and operations. * Make copies of objects or arrays before modifying them. * Employ libraries like Immutable.js for more complex scenarios. * **Don't Do This:** * Directly modify object properties or array elements. * Assume that passing an object or array creates a new copy. ### 3.1 JavaScript Immutability Techniques """javascript // Immutable Object Update const originalObject = { name: 'John', age: 30 }; const updatedObject = { ...originalObject, age: 31 }; // Create a new object // Immutable Array Update const originalArray = [1, 2, 3]; const updatedArray = [...originalArray, 4]; // Create a new array const removedArray = originalArray.filter(item => item !== 2); // Create new array without '2' console.log(originalObject); // { name: 'John', age: 30 } console.log(updatedObject); // { name: 'John', age: 31 } console.log(originalArray); // [1, 2, 3] console.log(updatedArray); // [1, 2, 3, 4] console.log(removedArray); // [1, 3] """ ### 3.2 Immutable.js Immutable.js provides persistent immutable data structures, improving performance and simplifying state management for complex applications. """javascript import { Map, List } from 'immutable'; // Immutable Map const originalMap = Map({ name: 'John', age: 30 }); const updatedMap = originalMap.set('age', 31); // Immutable List const originalList = List([1, 2, 3]); const updatedList = originalList.push(4); console.log(originalMap.toJS()); // { name: 'John', age: 30 } console.log(updatedMap.toJS()); // { name: 'John', age: 31 } console.log(originalList.toJS()); // [1, 2, 3] console.log(updatedList.toJS()); // [1, 2, 3, 4] """ ## 4. Handling Side Effects Side effects are operations that affect the state of the application outside of the current function or component. Properly managing side effects is crucial for maintaining predictable and testable code. * **Do This:** * Isolate side effects in dedicated functions or modules. * Use effect hooks (e.g., "useEffect" in React) to manage side effects in components. * Handle errors gracefully when performing side effects. * **Don't Do This:** * Perform side effects directly within reducers or pure functions. * Ignore potential errors in side effect operations. ### 4.1 Managing Effects with "useEffect" """javascript import React, { useState, useEffect } from 'react'; function DataFetcher({ url }) { const [data, setData] = useState(null); const [loading, setLoading] = useState(true); const [error, setError] = useState(null); useEffect(() => { const fetchData = async () => { try { const response = await fetch(url); if (!response.ok) { throw new Error("HTTP error! status: ${response.status}"); } const result = await response.json(); setData(result); } catch (e) { setError(e); } finally { setLoading(false); } }; fetchData(); // Cleanup function (optional) return () => { // Cancel any pending requests or subscriptions }; }, [url]); // Dependency array: effect runs only when 'url' changes if (loading) return <p>Loading...</p>; if (error) return <p>Error: {error.message}</p>; if (!data) return <p>No data available.</p>; return ( <pre>{JSON.stringify(data, null, 2)}</pre> ); } """ ### 4.2 Using Thunks with Redux Thunks allow you to perform asynchronous operations in Redux actions. """javascript // Example Redux Thunk Action const fetchDataRequest = () => ({ type: 'FETCH_DATA_REQUEST' }); const fetchDataSuccess = (data) => ({ type: 'FETCH_DATA_SUCCESS', payload: data }); const fetchDataFailure = (error) => ({ type: 'FETCH_DATA_FAILURE', payload: error }); // Async action using Redux Thunk const fetchData = (url) => { return async (dispatch) => { dispatch(fetchDataRequest()); try { const response = await fetch(url); if (!response.ok) { throw new Error("HTTP error! status: ${response.status}"); } const data = await response.json(); dispatch(fetchDataSuccess(data)); } catch (error) { dispatch(fetchDataFailure(error.message)); } }; }; // Usage in Component import { useDispatch } from 'react-redux'; function DataFetchButton({ url }) { const dispatch = useDispatch(); return ( <button onClick={() => dispatch(fetchData(url))}> Fetch Data </button> ); } """ ## 5. Testing State Management Testing state management involves verifying that state transitions occur correctly and that side effects are handled properly. * **Do This:** * Write unit tests for reducers to verify state transitions. * Use mock stores and actions to test components connected to Redux. * Test side effects by mocking external dependencies. * **Don't Do This:** * Omit testing for state management logic. * Write integration tests without proper unit testing. ### 5.1 Testing Reducers """javascript // Reducer Test Example (Jest) import counterReducer from './counterReducer'; // Assuming counterReducer.js import { INCREMENT, DECREMENT } from './actions'; describe('counterReducer', () => { it('should return the initial state', () => { expect(counterReducer(undefined, {})).toEqual({ count: 0 }); }); it('should handle INCREMENT', () => { expect(counterReducer({ count: 0 }, { type: INCREMENT })).toEqual({ count: 1 }); }); it('should handle DECREMENT', () => { expect(counterReducer({ count: 1 }, { type: DECREMENT })).toEqual({ count: 0 }); }); }); """ ### 5.2 Testing React Components with Redux """javascript // Component Test Example (React Testing Library and Redux Mock Store) import React from 'react'; import { render, fireEvent } from '@testing-library/react'; import { Provider } from 'react-redux'; import configureStore from 'redux-mock-store'; import CounterComponent from './CounterComponent'; // Assuming CounterComponent.js const mockStore = configureStore([]); describe('CounterComponent', () => { let store; let component; beforeEach(() => { store = mockStore({ count: 0 }); store.dispatch = jest.fn(); // Mock dispatch function component = render( <Provider store={store}> <CounterComponent /> </Provider> ); }); it('should display the initial count', () => { expect(component.getByText('Count: 0')).toBeInTheDocument(); }); it('should dispatch increment action when increment button is clicked', () => { fireEvent.click(component.getByText('Increment')); expect(store.dispatch).toHaveBeenCalledWith({ type: 'INCREMENT' }); }); }); """ ## 6. Security Considerations for State Management Security is a critical aspect of state management. Properly securing the state ensures that sensitive data is protected from unauthorized access and tampering. * **Do This:** * Protect sensitive data in the state with encryption. * Validate data received from external sources before storing it in the state. * Sanitize user input to prevent XSS. * **Don't Do This:** * Store sensitive data in plain text in the state. * Trust data received from external sources without validation. * Expose sensitive data in logs or error messages. ### 6.1 Data Validation """javascript // Example Data Validation const validateData = (data) => { if (typeof data.email !== 'string' || !data.email.includes('@')) { throw new Error('Invalid email format'); } if (typeof data.age !== 'number' || data.age < 0 || data.age > 120) { throw new Error('Invalid age'); } return data; }; // Usage in Reducer const userReducer = (state = {}, action) => { switch (action.type) { case 'UPDATE_USER': try { const validatedData = validateData(action.payload); return { ...state, ...validatedData }; } catch (error) { console.error('Data validation failed:', error.message); return state; } default: return state; } }; """ ### 6.2 Encryption Encrypting sensitive data ensures that even if the state is compromised, the data remains unreadable without the decryption key. """javascript // Example Encryption (using CryptoJS) import CryptoJS from 'crypto-js'; const encryptData = (data, key) => { const encrypted = CryptoJS.AES.encrypt(JSON.stringify(data), key).toString(); return encrypted; }; const decryptData = (encryptedData, key) => { const bytes = CryptoJS.AES.decrypt(encryptedData, key); try { const decrypted = JSON.parse(bytes.toString(CryptoJS.enc.Utf8)); return decrypted; } catch (e) { console.error("Decryption error", e); return null; // Or handle the error as appropriate } }; // Example usage const sensitiveData = { creditCardNumber: '1234-5678-9012-3456' }; const encryptionKey = 'my-secret-key'; const encryptedData = encryptData(sensitiveData, encryptionKey); console.log('Encrypted:', encryptedData); const decryptedData = decryptData(encryptedData, encryptionKey); console.log('Decrypted:', decryptedData); """ ## 7. Optimizing Performance Efficient state management is crucial for optimizing application performance, especially in complex applications with frequent state updates. * **Do This:** * Use memoization techniques to prevent unnecessary re-renders. * Implement lazy loading for components that rely on large state objects. * Batch state updates to minimize the number of renders. * **Don't Do This:** * Update the state unnecessarily. * Cause components to re-render frequently with negligible impact. ### 7.1 Memoization Memoization prevents re-renders by caching the results of expensive calculations or component renders. """javascript import React, { useState, useMemo } from 'react'; function ExpensiveComponent({ data }) { // Simulate an expensive computation const computedValue = useMemo(() => { console.log('Computing expensive value...'); // Complex calculation based on data return data.map(item => item * 2).reduce((acc, val) => acc + val, 0); }, [data]); // Only recompute if 'data' changes return ( <div> <p>Computed Value: {computedValue}</p> </div> ); } function ParentComponent() { const [count, setCount] = useState(0); const data = [1, 2, 3, 4, 5]; // Static data return ( <div> <button onClick={() => setCount(count + 1)}>Increment Count</button> <p>Count: {count}</p> {/*ExpensiveComponent only re-renders if "data" changes, not on count changes*/} <ExpensiveComponent data={data} /> </div> ); } function MemoizedComponent({ data }) { // Simulate a render-heavy component console.log('Rendering MemoizedComponent...'); return <p>Data: {data.join(', ')}</p>; } // Memoize MemoizedComponent to prevent unnecessary re-renders const OptimizedMemoizedComponent = React.memo(MemoizedComponent); function ParentMemoComponent() { const [count, setCount] = useState(0); const data = [1, 2, 3, 4, 5]; return ( <div> <button onClick={() => setCount(count + 1)}>Increment Count</button> <p>Count: {count}</p> {/* MemoizedComponent only re-renders if its props change, not on count changes */} <OptimizedMemoizedComponent data={data} /> </div> ); } """ ### 7.2 Batching Updates Batching updates ensures that multiple state updates are grouped into a single render cycle. """javascript import React, { useState } from 'react'; import { unstable_batchedUpdates } from 'react-dom'; // Available only in some React versions function BatchUpdatesComponent() { const [count1, setCount1] = useState(0); const [count2, setCount2] = useState(0); const updateBothCounts = () => { unstable_batchedUpdates(() => { // Both state updates are batched into a single render setCount1(prevCount => prevCount + 1); setCount2(prevCount => prevCount + 1); }); }; return ( <div> <p>Count 1: {count1}</p> <p>Count 2: {count2}</p> <button onClick={updateBothCounts}>Update Both Counts</button> </div> ); } """ These standards provide a comprehensive guide to managing state in a clean and maintainable way. By following these guidelines, developers can build robust, performant, and secure applications.
# API Integration Standards for Clean Code This document outlines coding standards and best practices for integrating with backend services and external APIs within the Clean Code framework. It emphasizes readability, maintainability, performance, and security. These standards are aimed at guiding developers and AI coding assistants in producing high-quality, robust, and scalable integrations. ## 1. API Integration Principles and Clean Code API integration, when approached with Clean Code principles in mind, becomes significantly more manageable and less prone to errors. This section explores the core principles and their applications in the context of API interactions. * **Single Responsibility Principle (SRP):** A class or module should have one, and only one, reason to change. For API integration, this means separating the API client logic (responsible for making requests and handling responses) from the business logic that uses the data. * **Do This:** Create dedicated classes or modules for interacting with specific APIs, encapsulating all the API-related logic within them. * **Don't Do This:** Mix API calls directly within business logic classes or functions. This makes testing and maintenance difficult. * **Why:** SRP ensures that a change in the API (e.g., endpoint change, data format update) only requires modification in the API client module, not the entire application. * **Open/Closed Principle (OCP):** Software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification. This principle applies to API integration by allowing new API features or versions to be adopted without modifying existing code that uses the API. * **Do This:** Use abstract classes or interfaces to define a contract for API clients. Implementations can then be created for different API versions or services. Utilize design patterns such as Strategy or Template Method. * **Don't Do This:** Directly modify existing API client code to accommodate new API features. * **Why:** OCP ensures that changes to the API don't introduce regressions in existing functionality. * **Liskov Substitution Principle (LSP):** Subtypes must be substitutable for their base types without altering the correctness of the program. This is relevant when using polymorphism with API clients. * **Do This:** Ensure that any derived API client classes adhere to the contract defined by the base class or interface. If a method implemented in a sub-class modifies behavior in an unexpected way, it violates LSP. * **Don't Do This:** Create API client subclasses that fundamentally change the behavior of the base class's methods. * **Why:** LSP ensures that you can replace one API client implementation with another without causing unexpected errors. * **Interface Segregation Principle (ISP):** Clients should not be forced to depend on methods they do not use. In the API realm, this translates to creating specific interfaces for different API functionalities, catering to the needs of different parts of the application. * **Do This:** Define multiple, smaller interfaces tailored to specific use cases, rather than a single large interface for the entire API. * **Don't Do This:** Force clients to implement methods they don't need, leading to bloated and confusing implementations. * **Why:** ISP promotes loose coupling and reduces the risk of unintended side effects when API contracts change. * **Dependency Inversion Principle (DIP):** High-level modules should not depend on low-level modules. Both should depend on abstractions. Abstractions should not depend on details. Details should depend on abstractions. In API integration, this means that business logic should depend on interfaces for API clients, not on concrete implementations. That allows easy swapping of implementations for testing, changing providers, or other needs. * **Do This:** Inject API client interfaces into classes that need to consume the API. * **Don't Do This:** Directly instantiate API client classes within business logic components. * **Why:** DIP promotes loose coupling, making testing easier, and allowing you to switch API providers without impacting the rest of your system. Dependency Injection (DI) frameworks are invaluable here. ## 2. Connecting with Backend Services and External APIs This section covers the practical aspects of connecting to APIs, including error handling, data transformation, and authentication. ### 2.1 Selecting an HTTP Client * **Standard:** Use a robust and well-maintained HTTP client library. Consider "aiohttp" (async) or "requests" (sync) for Python. For Javascript consider "axios" or the native "fetch" API. * **Do This:** Choose a library that supports features like connection pooling, automatic retries, timeouts, and request/response interceptors, and proper TLS/SSL verification. * **Don't Do This:** Write your own HTTP client or use a rudimentary library that lacks essential features. * **Why:** Using a mature HTTP client library simplifies development and reduces the risk of introducing bugs or security vulnerabilities. """python import requests def get_data_from_api(url): try: response = requests.get(url, timeout=10) # added timeout response.raise_for_status() # Raise HTTPError for bad responses (4xx or 5xx) return response.json() except requests.exceptions.RequestException as e: print(f"Error communicating with API: {e}") return None api_url = "https://example.com/api/data" data = get_data_from_api(api_url) if data: print(data) """ ### 2.2 Error Handling * **Standard:** Implement robust error handling to gracefully handle API failures. Use "try-except" blocks, check response codes, and log errors appropriately. Implement retry mechanisms with exponential backoff for transient errors. * **Do This:** Wrap API calls in "try-except" blocks to catch potential exceptions (e.g., network errors, timeouts, invalid responses). Use "response.raise_for_status()" to check for HTTP errors, making special consideration for rate limiting. Log the complete error message, request URL, and any relevant context. * **Don't Do This:** Ignore errors or simply print error messages without proper logging and handling. * **Why:** Proper error handling prevents application crashes, provides valuable debugging information, and ensures a better user experience. """python import requests import time import logging logging.basicConfig(level=logging.INFO) def get_data_from_api(url, max_retries=3, backoff_factor=2): # retry mechanism retries = 0 while retries < max_retries: try: response = requests.get(url, timeout=10) response.raise_for_status() return response.json() except requests.exceptions.RequestException as e: logging.error(f"Attempt {retries + 1} failed: {e}") retries += 1 time.sleep(backoff_factor ** retries) # Exponential backoff logging.error(f"Failed to retrieve data from {url} after {max_retries} attempts") return None """ ### 2.3 Data Transformation * **Standard:** Decouple the API's data format from your application's data model. Use data transfer objects (DTOs) or similar mechanisms to map the API response to your internal representation. * **Do This:** Create dedicated classes or functions to transform API responses into your application's data structures. Centralize this mapping logic to simplify changes. Use validation libraries like Pydantic (for Python) for structural validation and automated type conversion. * **Don't Do This:** Directly use the API's data format throughout your application. This tightly couples your code to the API and makes it difficult to adapt to changes. * **Why:** Data transformation ensures that your application remains independent of the specific API's data format, improving maintainability and flexibility. """python from pydantic import BaseModel import requests class User(BaseModel): # pydantic model id: int name: str email: str def get_user_from_api(user_id: int) -> User | None: url = f"https://example.com/api/users/{user_id}" try: response = requests.get(url) response.raise_for_status() user_data = response.json() return User(**user_data) # Validate and convert using Pydantic except requests.exceptions.RequestException as e: print(f"Error: {e}") return None user = get_user_from_api(1) if user: print(f"User name: {user.name}") """ ### 2.4 Authentication and Authorization * **Standard:** Implement secure authentication and authorization mechanisms according to the API's requirements (API Keys, OAuth 2.0, JWT). Store secrets securely using environment variables or dedicated secret management tools. * **Do This:** Use a dedicated library for handling authentication protocols. Store API keys and secrets securely (e.g., using environment variables or a vault). Properly handle token refresh flows in OAuth 2.0 when using access tokens with limited lifetimes. Use HTTPS for all API communication. * **Don't Do This:** Hardcode API keys or secrets in your code. Skip SSL/TLS verification. Store cryptographic keys anywhere in your source repository. * **Why:** Secure authentication and authorization protect your application and the API from unauthorized access. """python import os import requests API_KEY = os.environ.get("MY_API_KEY") # Store in environment variable def call_api_with_auth(url): headers = {"Authorization": f"Bearer {API_KEY}"} # authorization header response = requests.get(url, headers=headers) response.raise_for_status() return response.json() """ ### 2.5 Rate Limiting * **Standard:** Understand and respect the API's rate limits. Implement mechanisms to avoid exceeding these limits, such as caching, throttling, and exponential backoff with jitter. * **Do This:** Check the API's documentation for rate limits. Implement a throttling mechanism to control the number of requests per unit of time. Cache API responses when appropriate (especially for frequently accessed data that doesn't change often). Handle "429 Too Many Requests" errors gracefully using exponential backoff and jitter. * **Don't Do This:** Ignore rate limits and bombard the API with requests. This can lead to temporary or permanent blocking. * **Why:** Respecting rate limits ensures fair usage of the API and prevents your application from being blocked. """python import time import requests import logging import random logging.basicConfig(level=logging.INFO) def call_api_with_rate_limiting(url, delay=1): try: response = requests.get(url) response.raise_for_status() return response.json() except requests.exceptions.HTTPError as e: if e.response.status_code == 429: retry_after = int(e.response.headers.get("Retry-After", 60)) # get from header jitter = random.uniform(0, 1) # add jitter wait_time = retry_after + jitter logging.warning(f"Rate limit exceeded. Waiting {wait_time:.2f} seconds.") time.sleep(wait_time) return call_api_with_rate_limiting(url) # Recursive call! else: raise # Re-raise the exception for other errors time.sleep(delay) # delay for a specified time return response.json() """ ## 3. Design Patterns for API Integration Several design patterns can help improve the structure and maintainability of API integration code. ### 3.1 Facade Pattern * **Standard:** Use a facade to provide a simplified interface to a complex API. This hides the underlying complexity and makes it easier for clients to use the API. * **Do This:** Create a facade class that encapsulates the API client and provides a simple, high-level interface for common operations. * **Don't Do This:** Expose the raw API client directly to clients. This exposes unnecessary complexity and makes it harder to adapt to API changes. * **Why:** The Facade pattern shields calling code from the complexities of direct API interaction. """python import requests class WeatherAPIClient: BASE_URL = "https://api.weatherapi.com/v1" def __init__(self, api_key): self.api_key = api_key def get_current_weather(self, city): url = f"{self.BASE_URL}/current.json?key={self.api_key}&q={city}" response = requests.get(url) response.raise_for_status() return response.json() class WeatherFacade: def __init__(self, api_key): self.api_client = WeatherAPIClient(api_key) # encapsulates API def get_temperature(self, city): data = self.api_client.get_current_weather(city) return data["current"]["temp_c"] # simplified interface # Usage: weather_facade = WeatherFacade("YOUR_API_KEY") temperature = weather_facade.get_temperature("London") print(f"Temperature in London: {temperature}°C") """ ### 3.2 Adapter Pattern * **Standard:** Use an adapter to convert the interface of an API client class into another interface that clients expect. This is useful when integrating with APIs that have different interfaces. * **Do This:** Create an adapter class that implements the desired interface and delegates calls to the API client. Use this pattern to normalize interfaces from different API endpoint calls to make them consistent for calling code. * **Don't Do This:** Modify the API client class directly to fit the desired interface (violates OCP). * **Why:** The Adapter pattern allows integrating disparate API interfaces or data models into a common format. """python class OldAPI: def fetch_data(self): return {"old_data": "value"} class NewAPIInterface: def get_data(self): raise NotImplementedError class OldAPIToNewAPIAdapter(NewAPIInterface): # Adapter class def __init__(self, old_api): self.old_api = old_api def get_data(self): old_data = self.old_api.fetch_data() return {"new_data": old_data["old_data"]} old_api = OldAPI() adapter = OldAPIToNewAPIAdapter(old_api) new_data = adapter.get_data() print(new_data) # Output: {'new_data': 'value'} """ ### 3.3 Strategy Pattern * **Standard:** If you have multiple ways to call an API (different authentication methods, different endpoints for the same functionality, etc.) use the Strategy pattern to encapsulate each approach into a separate strategy class. This allows you to easily switch between strategies at runtime. * **Do This:** Define a common interface for all strategies. Create concrete strategy classes for each approach. Inject the desired strategy into the class that needs to call the API. * **Don't Do This:** Use conditional statements to switch between different approaches. This makes the code harder to read and maintain. * **Why:** Provides implementation flexibility and facilitates switching strategies without modifying the core logic. """python import requests class AuthStrategy: def apply_auth(self, request): raise NotImplementedError() class APIKeyAuth(AuthStrategy): def __init__(self, api_key): self.api_key = api_key def apply_auth(self, request): request.headers["X-API-Key"] = self.api_key return request class OAuth2Auth(AuthStrategy): def __init__(self, token): self.token = token def apply_auth(self, request): request.headers["Authorization"] = f"Bearer {self.token}" return request class APIClient: def __init__(self, auth_strategy: AuthStrategy): self.auth_strategy = auth_strategy def get(self, url): request = requests.Request("GET", url) prepared_request = self.auth_strategy.apply_auth(request) # apply strategy session = requests.Session() response = session.send(prepared_request.prepare()) response.raise_for_status() return response.json() # Usage: api_key_auth = APIKeyAuth("your_api_key") api_client_api_key = APIClient(api_key_auth) data = api_client_api_key.get("https://example.com/api/data") print(data) oauth2_auth = OAuth2Auth("your_oauth_token") api_client_oauth = APIClient(oauth2_auth) data = api_client_oauth.get("https://example.com/api/data") print(data) """ ## 4. Technology-Specific Considerations ### 4.1 Python * **Asyncio:** Utilize "asyncio" and "aiohttp" for asynchronous API calls to improve concurrency and performance in I/O-bound applications. * **Type Hints:** Use type hints extensively to improve code readability and catch type-related errors early. * **Pydantic:** Use Pydantic for data validation and serialization/deserialization of API requests and responses. * **Requests Library:** Using "requests" may block synchronous code so consider using threading to avoid impacting performance or using Asyncio libraries. ### 4.2 JavaScript * **Fetch API/Axios:** Use "fetch" (native) or "axios" (library) for making HTTP requests. Axios is typically preferred for providing additional error handling and legacy browser support. * **Async/Await:** Leverage "async/await" syntax for asynchronous API calls to improve code readability and maintainability. * **Typescript:** Enable TypeScript support to statically type check code during development, ensuring that API requests are correctly constructed, and API responses are properly handled. * **Node.js:** Utilize Node.js to process large amounts of asynchronous requests. ## 5. Testing API Integrations * **Standard:** Thoroughly test API integrations to ensure correctness, reliability, and performance. Use mock APIs or stubs to isolate your code during testing. * **Do This:** Write unit tests for API client classes, mocking the HTTP client to control the API responses. Use integration tests to verify the end-to-end flow, including actual API calls to a test environment. Consider contract testing to ensure that your API client adheres to the API's contract. * **Don't Do This:** Skip testing API integrations or rely solely on manual testing. This can lead to unexpected errors and regressions. * **Why:** Testing API integrations ensures that your application works correctly with the API and protects against changes in the API. """python import unittest from unittest.mock import patch import requests class MockResponse: def __init__(self, json_data, status_code): self.json_data = json_data self.status_code = status_code def json(self): return self.json_data def raise_for_status(self): if self.status_code >= 400: raise requests.exceptions.HTTPError("Error") class APITest(unittest.TestCase): @patch('requests.get') # Mock the requests.get method def test_get_data_from_api_success(self, mock_get): mock_response = MockResponse({"key": "value"}, 200) mock_get.return_value = mock_response from your_module import get_data_from_api # Import your function here data = get_data_from_api("http://example.com/api") self.assertEqual(data, {"key": "value"}) @patch('requests.get') def test_get_data_from_api_failure(self, mock_get): mock_response = MockResponse(None, 500) mock_response.raise_for_status = unittest.mock.Mock(side_effect=requests.exceptions.HTTPError("Error")) mock_get.return_value = mock_response from your_module import get_data_from_api data = get_data_from_api("http://example.com/api") self.assertIsNone(data) """ ## 6. Documentation * **Standard:** Document all API integrations, including the API's purpose, authentication methods, request/response formats, and error handling strategies. * **Do This:** Use docstrings to document API client classes and methods. Create separate documents or wikis to describe the API integration in more detail. Use tooling like Swagger or OpenAPI to document APIs and their integration points. * **Don't Do This:** Leave API integrations undocumented. This makes it difficult for others (and yourself in the future) to understand and maintain the code. * **Why:** Clear documentation is essential for maintainability and collaboration. ## 7. Security Considerations * **Standard:** Prioritize security when integrating with APIs. Enforce HTTPS, validate input, sanitize output, and protect against common web vulnerabilities. * **Do This:** Always use HTTPS for API communication. Validate all input data to prevent injection attacks. Sanitize all output data to prevent cross-site scripting (XSS) attacks. Follow the principle of least privilege when configuring API access controls. Protect against CSRF attacks. * **Don't Do This:** Store sensitive data in plain text. Trust user input without validation. Disable security features. * **Why:** Security vulnerabilities can expose sensitive data and compromise your application. By adhering to these standards, developers can ensure that API integrations are clean, maintainable, performant, and secure, aligning with the core principles of Clean Code.