test-writer

name	test-writer
description	Generates comprehensive unit tests and integration tests for existing code. Covers happy path, edge cases, and error conditions.
triggers	["write tests for","add tests","test this code","generate tests","improve test coverage"]

Test Writer Skill

Objective

Generate thorough, production-quality tests that cover functionality, edge cases, and error handling.

Steps

1. Read the code to understand public API, inputs, outputs, and side effects
2. Identify test cases:
   • Happy path (normal usage)
   • Edge cases (empty input, max values, boundary conditions)
   • Error cases (invalid input, missing data, timeout, permission denied)
   • State transitions (if stateful)
3. Write tests following the existing test patterns in the project
4. Add to test file using file_write or file_patch
5. Run tests with shell_exec to verify they pass

Test Quality Rules

• Each test tests ONE thing (single assertion focus)
• Test names describe the scenario: test_{function}_{scenario}_{expected}
• No test depends on another test's state
• Use proper setup/teardown (fixtures, temp dirs)
• Mock external dependencies, not internal logic
• Assert specific values, not just "no error"

Language-Specific Patterns

Rust

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_function_happy_path() {
        let result = function(valid_input);
        assert_eq!(result, expected);
    }

    #[test]
    fn test_function_edge_case() {
        let result = function(edge_input);
        assert!(result.is_ok());
    }
}

TypeScript

describe('Module', () => {
  it('should handle normal input', () => {
    expect(fn(input)).toBe(expected);
  });
});

Tools Used

• file_read — read source code
• code_symbols — find functions to test
• file_write / file_patch — write test code
• shell_exec — run tests