test-fixing – Coding skill for AI agents

Test Fixing

Systematically identify and fix all failing tests using smart grouping strategies.

When to Use

• Explicitly asks to fix tests ("fix these tests", "make tests pass")
• Reports test failures ("tests are failing", "test suite is broken")
• Completes implementation and wants tests passing
• Mentions CI/CD failures due to tests

Systematic Approach

1. Initial Test Run

Read project instructions, dependency manifests and CI configuration to identify the existing test command. Use make test only if that target exists and is the project contract. Inspect fixture/service requirements before running it; do not invoke production operations to obtain a baseline. Preserve pre-existing changes.

Analyze output for:

• Total number of failures
• Error types and patterns
• Affected modules/files

2. Smart Error Grouping

Group similar failures by:

• Error type: ImportError, AttributeError, AssertionError, etc.
• Module/file: Same file causing multiple test failure
• Root cause: Missing dependencies, API changes, refactoring impacts

Prioritize groups by:

• Number of affected tests (highest impact first)
• Dependency order (fix infrastructure before functionality)

3. Systematic Fixing Process

For each group (starting with highest impact):

1. Identify root cause

• Read relevant code
• Check recent changes with git diff
• Understand the error pattern

2. Implement fix

• Use the host's available file-editing tool for code changes
• Follow applicable project instructions and conventions
• Make minimal, focused changes

3. Verify fix

• Run subset of tests for this group
• Use pytest markers or file patterns:

     uv run pytest tests/path/to/test_file.py -v
     uv run pytest -k "pattern" -v
     

• Ensure group passes before moving on

4. Move to next group

4. Fix Order Strategy

Infrastructure first:

• Import errors
• Missing dependencies
• Configuration issues

Then API changes:

• Function signature changes
• Module reorganization
• Renamed variables/functions

Finally, logic issues:

• Assertion failures
• Business logic bugs
• Edge case handling

5. Final Verification

After all groups fixed:

• Run the project's verified complete test command
• Verify no regressions
• Check test coverage remains intact

Best Practices

• Fix one group at a time
• Run focused tests after each fix
• Use git diff to understand recent changes
• Look for patterns in failures
• Don't move to next group until current passes
• Keep changes minimal and focused
• Do not delete assertions, skip failing cases, lower coverage thresholds or change expected behavior merely to obtain green tests. A test update requires evidence that the product contract changed. Report unavailable dependencies, flaky failures and unexecuted checks explicitly.

Example Workflow

User: "The tests are failing after my refactor"

1. In a repository with a verified make test target, run it → 15 failures identified

2. Group errors:

• 8 ImportErrors (module renamed)
• 5 AttributeErrors (function signature changed)
• 2 AssertionErrors (logic bugs)

3. Fix ImportErrors first → Run subset → Verify

4. Fix AttributeErrors → Run subset → Verify

5. Fix AssertionErrors → Run subset → Verify

6. Run full suite → All pass ✓

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.