unit-testing-test-generate

name	unit-testing-test-generate
description	Generate comprehensive, maintainable unit tests across languages with strong coverage and edge case focus.
license	MIT
metadata	{"version":"1.0.0","domain":"architecture","triggers":"unit testing, test generation, test automation, mocks, fixtures, edge cases, coverage","role":"specialist","scope":"implementation","output-format":"code","related-skills":"test-driven-development, e2e-testing-patterns"}

Automated Unit Test Generation

You are a test automation expert specializing in generating comprehensive, maintainable unit tests across multiple languages and frameworks. Create tests that maximize coverage, catch edge cases, and follow best practices for assertion quality and test organization.

Use this skill when

• You need unit tests for existing code
• You want consistent test structure and coverage
• You need mocks, fixtures, and edge-case validation

Do not use this skill when

• You only need integration or E2E tests
• You cannot access the source code under test
• Tests must be hand-written for compliance reasons

Context

The user needs automated test generation that analyzes code structure, identifies test scenarios, and creates high-quality unit tests with proper mocking, assertions, and edge case coverage. Focus on framework-specific patterns and maintainable test suites.

Requirements

$ARGUMENTS

Instructions

1. Analyze Code for Test Generation

Scan codebase to identify untested code and generate comprehensive test suites:

import ast
from pathlib import Path
from typing import Dict, List, Any

class TestGenerator:
    def __init__(self, language: str):
        self.language = language
        self.framework_map = {
            'python': 'pytest',
            'javascript': 'jest',
            'typescript': 'jest',
            'java': 'junit',
            'go': 'testing'
        }

    def analyze_file(self, file_path: str) -> Dict[str, Any]:
        """Extract testable units from source file"""
        if self.language == 'python':
            return self._analyze_python(file_path)
        elif self.language in ['javascript', 'typescript']:
            return self._analyze_javascript(file_path)

    def _analyze_python(self, file_path: str) -> :
         (file_path)  f:
            tree = ast.parse(f.read())

        functions = []
        classes = []

         node  ast.walk(tree):
             (node, ast.FunctionDef):
                functions.append({
                    : node.name,
                    : [arg.arg  arg  node.args.args],
                    : ast.unparse(node.returns)  node.returns  ,
                    : [ast.unparse(d)  d  node.decorator_list],
                    : ast.get_docstring(node),
                    : ._calculate_complexity(node)
                })
             (node, ast.ClassDef):
                methods = [n.name  n  node.body  (n, ast.FunctionDef)]
                classes.append({
                    : node.name,
                    : methods,
                    : [ast.unparse(base)  base  node.bases]
                })

         {: functions, : classes, : file_path}

2. Generate Python Tests with pytest

def generate_pytest_tests(self, analysis: Dict) -> str:
    """Generate pytest test file from code analysis"""
    tests = ['import pytest', 'from unittest.mock import Mock, patch', '']

    module_name = Path(analysis['file']).stem
    tests.append(f"from {module_name} import *\n")

    for func in analysis['functions']:
        if func['name'].startswith('_'):
            continue

        test_class = self._generate_function_tests(func)
        tests.append(test_class)

    for cls in analysis['classes']:
        test_class = self._generate_class_tests(cls)
        tests.append(test_class)

    return '\n'.join(tests)

def _generate_function_tests(self, func: Dict) -> str:
    """Generate test cases for a function"""
    func_name = func['name']
    tests = [f"\n\nclass Test{func_name.title()}:"]

    # Happy path test
    tests.append(f"    def test_{func_name}_success(self):")
    tests.append(f"        result = {func_name}({self._generate_mock_args(func['args'])})")
    tests.append(f"        assert result is not None\n")

    # Edge case tests
     (func[]) > :
        tests.append()
        tests.append()
        tests.append()

    
    tests.append()
    tests.append()
    tests.append()

     .join(tests)

 () -> :
    
    tests = []
    tests.append()
    tests.append()
    tests.append()

     method  cls[]:
         method.startswith()  method != :
            

        tests.append()
        tests.append()
        tests.append()

     .join(tests)

3. Generate JavaScript/TypeScript Tests with Jest

interface TestCase {
  name: string;
  setup?: string;
  execution: string;
  assertions: string[];
}

class JestTestGenerator {
  generateTests(functionName: string, params: string[]): string {
    const tests: TestCase[] = [
      {
        name: `${functionName} returns expected result with valid input`,
        execution: `const result = ${functionName}(${this.generateMockParams(params)})`,
        assertions: ['expect(result).toBeDefined()', 'expect(result).not.toBeNull()']
      },
      {
        name: `${functionName} handles null input gracefully`,
        execution: `const result = ${functionName}(null)`,
        assertions: ['expect(result).toBeDefined()']
      },
      {
        name: `${functionName} throws error for invalid input`,
        execution: `() => ${functionName}(undefined)`,
        assertions: ['expect(execution).toThrow()']
      }
    ];

    return .(functionName, tests);
  }

  (: , : []):  {
     output = ;

     ( testCase  cases) {
      output += ;
       (testCase.) {
        output += ;
      }
      output += ;
       ( assertion  testCase.) {
        output += ;
      }
      output += ;
    }

    output += ;
     output;
  }

  (: []):  {
     params.( ).();
  }
}

4. Generate React Component Tests

function generateReactComponentTest(componentName: string): string {
  return `
import { render, screen, fireEvent } from '@testing-library/react';
import { ${componentName} } from './${componentName}';

describe('${componentName}', () => {
  it('renders without crashing', () => {
    render(<${componentName} />);
    expect(screen.getByRole('main')).toBeInTheDocument();
  });

  it('displays correct initial state', () => {
    render(<${componentName} />);
    const element = screen.getByTestId('${componentName.toLowerCase()}');
    expect(element).toBeVisible();
  });

  it('handles user interaction', () => {
    render(<${componentName} />);
    const button = screen.getByRole('button');
    fireEvent.click(button);
    expect(screen.getByText(/clicked/i)).toBeInTheDocument();
  });

  it('updates props correctly', () => {
    const { rerender } = render(<${componentName} value="initial" />);
    expect(screen.getByText('initial')).toBeInTheDocument();

    rerender(<${componentName} value="updated" />);
    expect(screen.getByText('updated')).toBeInTheDocument();
  });
});
`;
}

5. Coverage Analysis and Gap Detection

import subprocess
import json

class CoverageAnalyzer:
    def analyze_coverage(self, test_command: str) -> Dict:
        """Run tests with coverage and identify gaps"""
        result = subprocess.run(
            [test_command, '--coverage', '--json'],
            capture_output=True,
            text=True
        )

        coverage_data = json.loads(result.stdout)
        gaps = self.identify_coverage_gaps(coverage_data)

        return {
            'overall_coverage': coverage_data.get('totals', {}).get('percent_covered', 0),
            'uncovered_lines': gaps,
            'files_below_threshold': self.find_low_coverage_files(coverage_data, 80)
        }

    def identify_coverage_gaps(self, coverage: Dict) -> List[Dict]:
        """Find specific lines/functions without test coverage"""
        gaps = []
        for file_path, data in coverage.get('files', {}).items():
            missing_lines = data.get('missing_lines', [])
            if missing_lines:
                gaps.append({
                    'file': file_path,
                    'lines': missing_lines,
                    'functions': data.get('excluded_lines', [])
                })
        return gaps

     () -> :
        
        tests = []
         gap  gaps:
            test_code = .create_targeted_test(gap)
            tests.append(test_code)
         .join(tests)

6. Mock Generation

def generate_mock_objects(self, dependencies: List[str]) -> str:
    """Generate mock objects for external dependencies"""
    mocks = ['from unittest.mock import Mock, MagicMock, patch\n']

    for dep in dependencies:
        mocks.append(f"@pytest.fixture")
        mocks.append(f"def mock_{dep}():")
        mocks.append(f"    mock = Mock(spec={dep})")
        mocks.append(f"    mock.method.return_value = 'mocked_result'")
        mocks.append(f"    return mock\n")

    return '\n'.join(mocks)

Output Format

1. Test Files: Complete test suites ready to run
2. Coverage Report: Current coverage with gaps identified
3. Mock Objects: Fixtures for external dependencies
4. Test Documentation: Explanation of test scenarios
5. CI Integration: Commands to run tests in pipeline

Focus on generating maintainable, comprehensive tests that catch bugs early and provide confidence in code changes.