update with learnings

Author: eleanorjboyd

.github/instructions/testing-workflow.instructions.md

@@ -569,3 +569,5 @@ envConfig.inspect
 -   Create minimal mock objects with only required methods and use TypeScript type assertions (e.g., mockApi as PythonEnvironmentApi) to satisfy interface requirements instead of implementing all interface methods when only specific methods are needed for the test (1)
 -   When reviewing existing tests, focus on behavior rather than implementation details in test names and assertions - transform "should return X when Y" into "should [expected behavior] when [scenario context]" (1)
 -   Simplify mock setup by only mocking methods actually used in tests and use `as unknown as Type` for TypeScript compatibility (1)
+-   Avoid setting global default stub behaviors in setup() that require resetBehavior() calls; instead configure stub behaviors conditionally in each test to prevent conflicts and make tests self-contained (1)
+-   Use conditional stub configuration with withArgs() instead of multiple resolves() calls to prevent Sinon behavior conflicts - if you must override a stub, call resetBehavior() first to clear previous configurations (1)