Unit Test Generator

Overview

Automatically generate comprehensive unit tests from source code analysis covering happy paths, edge cases, boundary conditions, and error handling. Supports Jest, Vitest, Mocha (JavaScript/TypeScript), pytest (Python), JUnit 5 (Java), and Go testing with testify.

Prerequisites

• Testing framework installed and configured (jest, vitest, pytest, junit-jupiter, or Go testing)
• Source code with clear function signatures, type annotations, or JSDoc comments
• Test directory structure established (tests/, tests/, spec/, or *_test.go)
• Mocking library available (jest.mock, unittest.mock, Mockito, or gomock)
• Package scripts configured to run tests (npm test, pytest, go test)

Instructions

1. Scan the codebase with Glob to locate source files that lack corresponding test files (e.g., src/utils/parser.ts without tests/parser.test.ts).
2. Read each untested source file and extract:

• All exported functions and class methods with their signatures.
• Parameter types, return types, and thrown exceptions.
• External dependencies (imports from other modules, third-party libraries, I/O).
• Pure vs. impure function classification.

1. For each function, generate test cases in these categories:

• Happy path: Valid inputs producing expected outputs (at least 2 cases).
• Edge cases: Empty strings, empty arrays, zero, negative numbers, null, undefined, maximum values.
• Error conditions: Invalid types, missing required fields, network failures, permission errors.
• Boundary values: Off-by-one, integer overflow, string length limits.

1. Create mock declarations for all external dependencies:

• Database calls return predictable fixture data.
• HTTP clients return canned responses with configurable status codes.
• File system operations use in-memory buffers or temp directories.

1. Write the test file following project conventions:

• Match the existing test file naming pattern (.test.ts, .spec.js, test_*.py).
• Group tests in describe/context blocks by function name.
• Use beforeEach/afterEach for setup and teardown.
• Include inline comments explaining non-obvious test rationale.

1. Run the generated tests to verify they pass, then check coverage to confirm the target funct