Many developers are writing integration tests the wrong way - they write Broad Integration Tests, which have similar limitations as E2E Tests - limited scenarios, brittle & fragile.
We should strive for having "enough" tests, not more, not less. The number of tests that we are required is:
- We should have an Acceptance Test for every Acceptance Criteria
- Regarding data examples, we can use Boundary Value Analysis & Equivalence Partitioning
- We should have just enough External System Contract Tests so that every integration endpoint is covered, based on different response types it can give (e.g. HTTP 200, HTTP 400 cases)
As we go downwards:
- We should have just enough Component Level Tests so that when they sum up, we get Acceptance Tests. This could be distributed through (a) Component Tests alone, or (b) Unit Tests & Narrow Integration Tests, with few Component Tests.
- We should have just enough Contract Tests so that every integration endpoint is covered, based on different response types it can give (e.g. HTTP 200, HTTP 400 cases)
Sometimes developers complain that "we already have so many tests" - but maybe the real problem is not having tests at the right levels?
We should strive for having "enough" tests, not more, not less. The number of tests that we are required is:
- We should have an Acceptance Test for every Acceptance Criteria
- Regarding data examples, we can use Boundary Value Analysis & Equivalence Partitioning
- We should have just enough External System Contract Tests so that every integration endpoint is covered, based on different response types it can give (e.g. HTTP 200, HTTP 400 cases)
As we go downwards:
- We should have just enough Component Level Tests so that when they sum up, we get Acceptance Tests. This could be distributed through (a) Component Tests alone, or (b) Unit Tests & Narrow Integration Tests, with few Component Tests.
- We should have just enough Contract Tests so that every integration endpoint is covered, based on different response types it can give (e.g. HTTP 200, HTTP 400 cases)