mocking-test-generator

Mocking Test Generator

Generate unit tests with proper mocking of external dependencies for Python and Java code.

Workflow

1. Analyze the code - Identify external dependencies, side effects, and testable units
2. Select framework - Determine Python (unittest.mock/pytest) or Java (Mockito/JUnit)
3. Generate mocks - Create mock objects for external dependencies
4. Write tests - Generate executable test code with assertions
5. Add documentation - Include clear comments explaining mocks and test logic

Step 1: Analyze the Code

Read the target code to identify:

• External dependencies: API clients, database connections, third-party libraries
• I/O operations: File reads/writes, network requests, system calls
• Side effects: Email sending, logging, state modifications
• Testable units: Functions, methods, or classes to test in isolation

Ask clarifying questions if:

• Multiple functions/classes exist (which to test?)
• Testing scope is unclear (unit vs integration?)
• Mock behavior needs specification (return values, exceptions?)

Step 2: Select Framework

Python: Use unittest.mock with pytest or unittest

• Prefer @patch decorator for external calls
• Use Mock() objects for complex dependencies
• Apply pytest.fixture for reusable mocks

Java: Use Mockito with JUnit 5

• Use @Mock annotation for dependencies
• Apply @ExtendWith(MockitoExtension.class) to test class
• Use when().thenReturn() for stubbing

Step 3: Generate Mocks

Identify what to mock:

Always mock:

• External API calls (HTTP requests, REST clients)
• Database connections and queries
• File system operations
• Network I/O
• Time/date functions
• Random number generators
• Environment variables

Never mock (unless explicitly requested):

• Internal business logic
• Pure functions
• Data structures
• Simple utilities

For common patterns, reference:

• Python: See references/python_patterns.md
• Java: See references/java_patterns.md