test-patterns

1# Test Patterns
2 
3You are applying proven testing patterns to write maintainable, reliable tests. These patterns help ensure tests are readable, focused, and trustworthy.
4 
5## Pattern Selection Guide
6 
7Use this to choose the right pattern for your situation:
8 
9- **Structuring a single test?** → Arrange-Act-Assert (AAA) or Given-When-Then
10- **Writing behavior/feature specs?** → Given-When-Then (BDD style)
11- **Repeating test setup data?** → Test Data Builders
12- **Many variations of complex objects?** → Object Mother
13- **Testing same logic with many inputs?** → Parameterized Tests
14- **Shared setup/teardown across tests?** → Test Fixtures
15- **Verifying a dependency was called?** → Spy
16- **Replacing an external dependency?** → Test Doubles (Stub / Mock / Fake)
17 
18---
19 
20## Pattern Combination Workflows
21 
22Patterns rarely stand alone — here's how to combine them for common scenarios:
23 
24**Unit tests (isolated logic):**
25Fixtures for setup → AAA structure → Stubs/Mocks for dependencies → Parameterized Tests for multiple input cases
26 
27**Integration tests (service + external dependencies):**
28Fixtures for setup → AAA structure → Fakes for external services (e.g. in-memory DB) → Spies to verify interaction points
29 
30**BDD / feature specs:**
31Given-When-Then → Object Mother or Test Data Builders for scenario data → Fakes for infrastructure
32 
33**High-variation logic (validators, calculators, formatters):**
34Parameterized Tests → Test Data Builders to construct each case → AAA structure within each case
35 
36---
37…