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Generate Tests Workflow

Workflow File: .github/workflows/generate-tests.yml

This workflow analyzes commits for missing unit test coverage and automatically creates issues for Copilot to write the tests.

Overview

The Generate Tests workflow uses GitHub Copilot CLI to examine code changes and identify when new or modified code lacks corresponding unit tests. By automating test coverage analysis, teams can maintain high code quality without manual review overhead.

How It Works

flowchart TD
    A[Push to Repository] --> B{Source files changed?}
    B -->|No| C[Skip workflow]
    B -->|Yes| D[Install Copilot CLI]
    D --> E[Load analyze-tests prompt]
    E --> F[Copilot analyzes code changes]
    F --> G{Tests missing?}
    G -->|No| H[Exit - Coverage adequate]
    G -->|Yes| I[Create GitHub Issue]
    I --> J[Assign Copilot Coding Agent]
    J --> K[Agent writes missing tests]
    K --> L[PR created with tests]
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Step-by-Step Process

  1. Triggers on every push (excluding non-source files)
  2. Installs Copilot CLI in the GitHub Actions runner
  3. Loads the analyze-for-tests prompt from .github/prompts/analyze-for-tests.prompt.md
  4. Copilot checks if new code has corresponding tests
  5. If tests are missing → Creates a GitHub issue and assigns Copilot
  6. Copilot Coding Agent then writes the missing tests

Criteria for Tests

✅ Tests ARE Needed

Change Type Example
New Functions/Methods calculateDiscount(), validateOrder()
New Classes WarehouseService, OrderProcessor
Modified Business Logic Changed calculation formulas, updated validation
New API Endpoints REST routes, GraphQL resolvers
Error Handling Paths Try/catch blocks, error conditions

❌ Tests NOT Needed

Change Type Example
Configuration Files tsconfig.json, package.json
Type Definitions Only Interface declarations, type aliases
Test Files Themselves *.test.ts, *.spec.ts
Documentation README, comments, JSDoc
Static Assets Images, fonts, CSS

Configuration

Trigger Configuration

The workflow focuses on source code changes:

on:
  push:
    paths:
      - 'api/src/**/*.ts'
      - 'frontend/src/**/*.ts'
      - 'frontend/src/**/*.tsx'
    paths-ignore:
      - '**/*.test.ts'
      - '**/*.spec.ts'
      - '**/*.d.ts'

Required Secrets

Secret Description
COPILOT_CLI_TOKEN Personal Access Token with Copilot permissions

Prompt File

The workflow uses a specialized prompt to guide Copilot's analysis:

Location: .github/prompts/analyze-for-tests.prompt.md

This prompt instructs Copilot to:

  • Analyze the git diff for testable code changes
  • Identify functions, classes, and methods without test coverage
  • Evaluate if existing tests cover the modified code paths
  • Create a detailed issue listing specific tests to write

Example Issue Created

When the workflow detects missing tests, it creates an issue like:

## 🧪 Unit Tests Needed

**Commit**: def5678
**Author**: @developer

### Code Requiring Tests

#### `api/src/routes/warehouse.ts`
- [ ] `POST /` - Create warehouse endpoint
- [ ] `GET /` - Get all warehouses
- [ ] `GET /:id` - Get warehouse by ID
- [ ] `GET /branch/:branchId` - Get warehouses by branch
- [ ] `PUT /:id` - Update warehouse
- [ ] `DELETE /:id` - Delete warehouse

### Test File Location
`api/src/routes/warehouse.test.ts`

### Testing Framework
Vitest with supertest for API testing

/assign @copilot

Test Patterns Used

The Copilot Coding Agent follows established testing patterns in the codebase

API Route Tests

import { describe, it, expect, beforeEach } from 'vitest';
import request from 'supertest';
import app from '../index';

describe('Warehouse Routes', () => {
  describe('GET /api/warehouses', () => {
    it('should return all warehouses', async () => {
      const response = await request(app).get('/api/warehouses');
      expect(response.status).toBe(200);
      expect(Array.isArray(response.body)).toBe(true);
    });
  });

  describe('GET /api/warehouses/:id', () => {
    it('should return 404 for non-existent warehouse', async () => {
      const response = await request(app).get('/api/warehouses/99999');
      expect(response.status).toBe(404);
    });
  });
});

Troubleshooting

Workflow Not Triggering

  • Verify the push includes files matching the paths patterns
  • Ensure changes are not exclusively in paths-ignore patterns
  • Check that the workflow file exists in the default branch

Copilot Not Detecting Missing Tests

  • Review the generate-tests prompt for coverage criteria
  • Ensure the code changes are substantial enough to warrant tests
  • Check workflow logs for the analysis output

Agent Writing Incorrect Tests

  • Verify existing test patterns in the codebase are consistent
  • Check that the testing framework is correctly configured
  • Review the prompt for framework-specific instructions

Tests Failing After Generation

  • Run tests locally to identify issues
  • Check for missing imports or dependencies
  • Verify mock data matches the expected schema