Write Tests

Detect Project Test Environment

Package/Project Files

!ls package.json pytest.ini pyproject.toml setup.cfg tox.ini go.mod Cargo.toml *.csproj *.sln Gemfile build.gradle pom.xml mix.exs deno.json 2>/dev/null

Existing Tests

!find . -type f \( -name "*.test.*" -o -name "*.spec.*" -o -name "test_*" -o -name "*_test.*" -o -name "*_spec.*" -o -name "*Test.*" -o -name "*Spec.*" \) -not -path "*/node_modules/*" -not -path "*/.git/*" -not -path "*/vendor/*" 2>/dev/null | head -20

Test Config

!cat jest.config.* vitest.config.* pytest.ini pyproject.toml setup.cfg .rspec 2>/dev/null | head -50

Instructions

Step 1: Analyze the Target

1. Read the file or function to be tested
2. Identify all public APIs, functions, methods, and classes
3. Map out the code paths: conditionals, loops, error throws, early returns
4. Identify external dependencies that need mocking

Step 2: Determine Test Framework

Based on the detected project files:

• JavaScript/TypeScript: Jest, Vitest, Mocha, or Playwright (check package.json)
• Python: pytest, unittest (check pyproject.toml, pytest.ini)
• Go: standard testing package
• Rust: built-in #[cfg(test)] module
• C#/.NET: xUnit, NUnit, or MSTest
• Ruby: RSpec or Minitest
• Java: JUnit 5 or TestNG
• Elixir: ExUnit

Step 3: Follow Existing Patterns

• Find the nearest existing test file for a similar module
• Match the structure: describe/it, test classes, test functions
• Match the mocking approach: jest.mock, unittest.mock, testify, etc.
• Match the assertion style: expect, assert, should
• Match the file naming convention and directory placement

Step 4: Generate Tests

Write tests covering ALL of the following categories:

#### Happy Path

• Normal inputs produce expected outputs
• Standard use cases work correctly
• Return values and side effects are verified

#### Edge Cases

• Empty inputs (null, undefined, empty string, empty array, zero)
• Boundary values (min, max, off-by-one)
• Unicode and special characters where relevant
• Large inputs (performance boundary)

#### Error Conditions

• Invalid inputs produce appropriate errors
• Thrown exceptions match expected types and messages
• Error callbacks/handlers are invoked correctly
• Graceful degradation for partial failures

#### Async Behavior (if applicable)

• Promises resolve/reject correctly
• Async/await error handling
• Concurrent operations
• Timeout and cancellation

#### Mocking

• Mock external dependencies at module boundaries
• Verify mock calls (called with correct args, correct number of times)
• Reset mocks between tests
• Do NOT mock the unit under test

Step 5: Test Quality Rules

• One assertion concept per test (multiple asserts OK if testing one thing)
• Test names are full English sentences describing the scenario
• Use beforeEach/setUp for shared setup; afterEach/tearDown for cleanup
• Tests must be deterministic — no random data, no time-dependent assertions
• Tests must be independent — no shared mutable state between tests

Step 6: Output

Generate a complete, ready-to-save test file with:

• A header comment explaining what is tested
• All necessary imports
• Properly structured test suites
• The target coverage goal (aim for >80%)

Place the file following the project's test directory convention.