How to Review Claude-Generated .NET Tests for Real Regression Coverage
Claude-generated .NET tests can look complete and still miss the regression they are meant to catch. The author walks through tracing assertions back to their inputs, checking mock boundaries, and verifying that a test fails for the intended reason. It is a practical review checklist for anyone accepting agent-written tests into a C# codebase.
Key points
- Review each test as a behavioral claim: the input, the boundary and the observable outcome, not the method name.
- Trace assertions backwards from the act phase; conditional assertions can skip the branch that matters.
- Check whether a mock or fake removes the very behavior the test claims to cover.
- Be explicit about the expected failure: exception type, error result, response status or retry behavior.
- Observe red before the fix and green after it, and keep the actual failure output.
- Confirm the targeted run discovered the expected tests; an empty filter selection can look like success.
Generated tests often look thorough while proving little. A descriptive name and a green run do not show that a test would catch the regression it targets. Review each test as a behavioral claim: the input, the valid-invalid boundary, and the observable outcome. Read it backwards from the assertion, and watch for conditional assertions, early-returning helpers and mocks that replace the behavior under test.
The sample test passes zero instead of a negative count, so its conditional assertion never checks the rule. A stronger version expects an exception for negative inputs and checks the value at the valid boundary. Removing the guard should turn those cases red. Record failures on unfixed code and passes after the fix; a green run covers only its environment.
Real-world use
- Adding invalid-input tests to a delivery or pricing library that Claude Code generated.
- Reviewing an agent-authored pull request before merging, to confirm the tests exercise the changed contract.
- Checking that a bug fix is backed by a regression test that fails on the unfixed code.
Why it matters
A green test count does not guarantee protection against regressions. Reviewing agent-written tests by their inputs, executed production path and failure condition is what turns them into useful evidence.