Copilot instructions

1---
2description: Rails Testing Guide
3applyTo: "test/**/*_test.rb"
4---
5 
6# Rails Testing Guide
7 
8## Core Philosophy
9 
10- Test-Driven Development (TDD) as default practice
11- Use Minitest and fixtures, not RSpec or factories
12- Test behavior, not implementation details
13- Keep tests fast, focused, and reliable
14- Write tests that serve as documentation
15 
16## Testing Principles
17 
18- Write tests first, then implementation
19- One assertion per test when possible
20- Test the happy path and edge cases
21- Keep test data realistic and minimal
22- Make tests independent and repeatable
23 
24## Test Organization
25 
26- Mirror app structure in test directory
27- Group related tests in the same file
28- Use descriptive test names
29- Keep test files focused and manageable
30- Organize tests by feature or behavior
31 
32## Fixtures Best Practices
33 
34- Use fixtures for test data, not factories
35- Keep fixtures simple and realistic
36- Reference fixtures by meaningful names
37- Share fixtures across related tests
38- Update fixtures when models change
39 
40## Model Testing
41 
42- Test all validations thoroughly
43- Verify associations work correctly
44- Test scopes with various data sets
45- Check business logic and calculations
46- Ensure callbacks behave properly
47 
48## Controller Testing
49 
50- Focus on HTTP concerns only
51- Test authentication and authorization
52- Verify response formats and status codes
53- Check parameter filtering
54- Test error handling scenarios
55 
56## System Testing
57 
58- Test complete user workflows
59- Use Capybara for browser automation
60- Test JavaScript interactions
61- Verify Turbo Frame updates
62- Check responsive behavior
63 
64## Service Object Testing
65 
66- Test services in complete isolation
67- Mock external dependencies
68- Verify success and failure paths
69- Test edge cases and error conditions
70- Ensure proper transaction handling
71 
72## Integration Testing
73 
74- Test API endpoints thoroughly
75- Verify request/response cycles
76- Test authentication flows
77- Check cross-controller workflows
78- Validate data consistency
79 
80## Test Data Management
81 
82- Keep test data minimal and focused
83- Use fixtures for common scenarios
84- Create data in tests for specific cases
85- Clean up after tests when needed
86- Avoid test data dependencies
87 
88## Mocking and Stubbing
89 
90- Mock external services only
91- Avoid mocking your own objects
92- Use stubs for time-dependent code
93- Keep mocks simple and obvious
94- Document why mocking is necessary
95 
96## Test Performance
97 
98- Keep individual tests under 1 second
99- Use parallel testing for speed
100- Profile slow tests regularly
101- Optimize database operations
102- Cache expensive test setup
103 
104## Test Coverage
105 
106- Aim for high coverage without obsessing
107- Focus on critical business logic
108- Test error paths thoroughly
109- Don't test framework code
110- Use coverage as a guide, not a goal
111 
112## Continuous Integration
113 
114- Run tests on every commit
115- Keep CI builds fast
116- Fix broken tests immediately
117- Test multiple Ruby versions
118- Monitor test reliability
119 
120## Test Helpers
121 
122- Create helpers for common test patterns
123- Keep helpers focused and reusable
124- Document helper methods clearly
125- Share helpers across test types
126- Avoid complex helper logic
127 
128## Testing JavaScript
129 
130- Use system tests for JavaScript behavior
131- Test Stimulus controllers thoroughly
132- Verify Turbo interactions work
133- Check progressive enhancement
134- Test without JavaScript enabled
135 
136## API Testing
137 
138- Test all endpoints and methods
139- Verify authentication requirements
140- Check response formats and schemas
141- Test rate limiting and throttling
142- Validate error responses
143 
144## Background Job Testing
145 
146- Test job logic separately from queuing
147- Verify job parameters and execution
148- Test retry and failure scenarios
149- Check job side effects
150- Ensure idempotency
151 
152## Email Testing
153 
154- Test email delivery and content
155- Verify recipient and sender details
156- Check email templates render correctly
157- Test attachments and multipart emails
158- Validate email queueing
159 
160## Security Testing
161 
162- Test authorization for all actions
163- Verify parameter filtering works
164- Check for SQL injection vulnerabilities
165- Test CSRF protection
166- Validate input sanitization
167 
168## Performance Testing
169 
170- Profile critical code paths
171- Test with realistic data volumes
172- Monitor query counts
173- Check memory usage
174- Benchmark important operations
175 
176## Test Maintenance
177 
178- Refactor tests alongside code
179- Remove obsolete tests promptly
180- Keep tests DRY but readable
181- Update tests when requirements change
182- Review test quality regularly
183 
184## Common Anti-Patterns
185 
186- Testing implementation instead of behavior
187- Overly complex test setup
188- Brittle tests dependent on order
189- Testing framework functionality
190- Slow test suites that discourage TDD
191 
192## Debugging Tests
193 
194- Use byebug for test debugging
195- Add descriptive failure messages
196- Check test logs for details
197- Isolate failing tests
198- Verify test environment setup
199 
200## Best Practices Summary
201 
202- Write tests first
203- Keep tests simple and fast
204- Use fixtures over factories
205- Test behavior, not implementation
206- Maintain tests like production code
207 
208Remember: Tests are your safety net and documentation. Write them first, keep them simple, and maintain them well.
209