Write Failing Test
This skill is invoked from the /repro workflow. The issue ID, repro dir, reproduction status, and root cause are in conversation context from prior phases.
Determine Test Type
| Bug Type |
Test Type |
Location |
| Backend logic, query processor, API |
Clojure unit test |
test/metabase/... |
| Frontend UI behavior, rendering |
Jest unit/component test |
frontend/test/... or co-located *.unit.spec.ts/*.unit.spec.tsx |
| End-to-end user workflow, UI interaction |
Cypress acceptance test |
e2e/test/scenarios/... |
| Mixed (backend + frontend) |
Both — Clojure test for data + frontend/e2e test for UI |
|
Find Relevant Test File
Use the root cause to identify source file(s), then locate the corresponding test file:
Backend: src/metabase/foo/bar.clj → test/metabase/foo/bar_test.clj
Frontend: frontend/src/metabase/foo/Bar.tsx → frontend/src/metabase/foo/Bar.unit.spec.tsx or frontend/test/metabase/foo/Bar.unit.spec.tsx
E2E: UI workflow → e2e/test/scenarios/<category>/foo.cy.spec.ts
Use Grep to search for existing tests related to the buggy function/component. Consult CLAUDE.md in the source worktree for test conventions.
Choose Test Approach
Backend (Clojure):
| Root Cause Type |
Test Approach |
| Query processor bug |
mt/process-query or qp/process-query |
| API endpoint bug |
mt/user-http-request |
| Model / data bug |
mt/with-temp + t2/select |
| Pure logic / edge case |
Direct function call with specific inputs |
Frontend (TypeScript):
| Root Cause Type |
Test Approach |
| Component rendering bug |
Jest + React Testing Library — render component, assert DOM |
| User interaction bug |
Cypress — visit page, interact, assert visible result |
| Data display / formatting |
Jest unit test on the formatting/transform function |
| State management bug |
Jest — test reducer/action/selector with specific inputs |
Look at existing tests in the file for patterns to follow.
Write the Test
Add a new test to the appropriate test file in ./repro/<ISSUE-ID>/source/. The test should:
- Be minimal — only test the specific failing behavior
- Follow existing patterns in the file (imports, fixtures, helpers, assertion style)
- Have a descriptive name referencing the issue: e.g.,
(deftest issue-12345-test ...), it("should handle X (issue #12345)"), it("should not show X when Y (metabase#12345)")
- Assert the correct/expected behavior — the test should FAIL against the buggy code
Run the Test
mcp__metabase-repro__run_test(repro_dir="repro/<ISSUE-ID>", test_file="test/metabase/foo/bar_test.clj")
- Clojure tests (
.clj): Connects to running REPL, adds test/dev paths, requires namespace, runs tests.
- Jest tests (
.unit.spec.ts(x)): Runs yarn test-unit in the source worktree.
- Cypress tests (
.cy.spec.ts): Runs yarn test-cypress-run with CYPRESS_BASE_URL set.
The tool reports whether the test failed (expected — demonstrates the bug) or passed (unexpected — revisit test logic).
Generate and Save Diff
mcp__metabase-repro__save_test_patch(repro_dir="repro/<ISSUE-ID>")
Saves all changes (including new untracked files) to ./repro/<ISSUE-ID>/test-diff.patch.
Troubleshooting
- Edit tool failures: Re-read the file and retry once. If still failing, use Write tool for the complete file. Do NOT use Bash workarounds (
cat >>, cp, python3 -c).
- Bash restrictions in CI: Many Bash commands are blocked. Always use
run_test MCP tool — do NOT attempt raw shell commands.
- Can't write a useful test: Note the attempt and reason in the report, move on to Phase 6.
run_test fails twice: Write an inline REPL snippet instead or skip test execution — the patch is still valuable.- Large enterprise tests: If
run_test times out on a large file in enterprise/backend/test/, write a minimal inline REPL snippet instead.
- Node version errors in CI: Do NOT attempt manual yarn/jest/cypress. Document as "verified by code review, could not execute in CI due to Node version mismatch".
- Jest/Cypress tooling failures: Save the test patch — it's valid evidence even without execution. Note the tooling error in the report.
run_test returns nil: Ensure setup_worktree was called before start_metabase.
If Metabase was started first, restart it to pick up test paths.- Test namespaces unavailable: Restart Metabase after
setup_worktree.
- Dynamic column aliases: For tests involving
lib/desired-column-alias, retrieve the alias dynamically from lib/returned-columns rather than hardcoding. Aliases differ by metadata provider.
1---2name: write-test3description: Write a failing test for a reproduced Metabase bug. Invoked from the /repro workflow when status is REPRODUCED. Determines test type (Clojure/Jest/Cypress), finds the right test file, writes a minimal failing test, runs it, and saves a patch.4---56# Write Failing Test78This skill is invoked from the `/repro` workflow. The issue ID, repro dir, reproduction status, and root cause are in conversation context from prior phases.910## Determine Test Type1112| Bug Type | Test Type | Location |13|----------|-----------|----------|14| Backend logic, query processor, API | **Clojure unit test** | `test/metabase/...` |15| Frontend UI behavior, rendering | **Jest unit/component test** | `frontend/test/...` or co-located `*.unit.spec.ts`/`*.unit.spec.tsx` |16| End-to-end user workflow, UI interaction | **Cypress acceptance test** | `e2e/test/scenarios/...` |17| Mixed (backend + frontend) | **Both** — Clojure test for data + frontend/e2e test for UI |1819## Find Relevant Test File2021Use the root cause to identify source file(s), then locate the corresponding test file:2223**Backend**: `src/metabase/foo/bar.clj` → `test/metabase/foo/bar_test.clj`24**Frontend**: `frontend/src/metabase/foo/Bar.tsx` → `frontend/src/metabase/foo/Bar.unit.spec.tsx` or `frontend/test/metabase/foo/Bar.unit.spec.tsx`25**E2E**: UI workflow → `e2e/test/scenarios/<category>/foo.cy.spec.ts`2627Use Grep to search for existing tests related to the buggy function/component. Consult `CLAUDE.md` in the source worktree for test conventions.2829## Choose Test Approach3031**Backend (Clojure)**:3233| Root Cause Type | Test Approach |34|----------------|--------------|35| Query processor bug | `mt/process-query` or `qp/process-query` |36| API endpoint bug | `mt/user-http-request` |37| Model / data bug | `mt/with-temp` + `t2/select` |38| Pure logic / edge case | Direct function call with specific inputs |3940**Frontend (TypeScript)**:4142| Root Cause Type | Test Approach |43|----------------|--------------|44| Component rendering bug | Jest + React Testing Library — render component, assert DOM |45| User interaction bug | Cypress — visit page, interact, assert visible result |46| Data display / formatting | Jest unit test on the formatting/transform function |47| State management bug | Jest — test reducer/action/selector with specific inputs |4849Look at existing tests in the file for patterns to follow.5051## Write the Test5253Add a new test to the appropriate test file in `./repro/<ISSUE-ID>/source/`. The test should:54- **Be minimal** — only test the specific failing behavior55- **Follow existing patterns** in the file (imports, fixtures, helpers, assertion style)56- **Have a descriptive name** referencing the issue: e.g., `(deftest issue-12345-test ...)`, `it("should handle X (issue #12345)")`, `it("should not show X when Y (metabase#12345)")`57- **Assert the correct/expected behavior** — the test should FAIL against the buggy code5859## Run the Test6061```62mcp__metabase-repro__run_test(repro_dir="repro/<ISSUE-ID>", test_file="test/metabase/foo/bar_test.clj")63```6465- **Clojure tests** (`.clj`): Connects to running REPL, adds test/dev paths, requires namespace, runs tests.66- **Jest tests** (`.unit.spec.ts(x)`): Runs `yarn test-unit` in the source worktree.67- **Cypress tests** (`.cy.spec.ts`): Runs `yarn test-cypress-run` with `CYPRESS_BASE_URL` set.6869The tool reports whether the test **failed** (expected — demonstrates the bug) or **passed** (unexpected — revisit test logic).7071## Generate and Save Diff7273```74mcp__metabase-repro__save_test_patch(repro_dir="repro/<ISSUE-ID>")75```7677Saves all changes (including new untracked files) to `./repro/<ISSUE-ID>/test-diff.patch`.7879## Troubleshooting8081- **Edit tool failures**: Re-read the file and retry once. If still failing, use Write tool for the complete file. Do NOT use Bash workarounds (`cat >>`, `cp`, `python3 -c`).82- **Bash restrictions in CI**: Many Bash commands are blocked. Always use `run_test` MCP tool — do NOT attempt raw shell commands.83- **Can't write a useful test**: Note the attempt and reason in the report, move on to Phase 6.84- **`run_test` fails twice**: Write an inline REPL snippet instead or skip test execution — the patch is still valuable.85- **Large enterprise tests**: If `run_test` times out on a large file in `enterprise/backend/test/`, write a minimal inline REPL snippet instead.86- **Node version errors in CI**: Do NOT attempt manual yarn/jest/cypress. Document as "verified by code review, could not execute in CI due to Node version mismatch".87- **Jest/Cypress tooling failures**: Save the test patch — it's valid evidence even without execution. Note the tooling error in the report.88- **`run_test` returns nil**: Ensure `setup_worktree` was called before `start_metabase`.89 If Metabase was started first, restart it to pick up test paths.90- **Test namespaces unavailable**: Restart Metabase after `setup_worktree`.91- **Dynamic column aliases**: For tests involving `lib/desired-column-alias`, retrieve the alias dynamically from `lib/returned-columns` rather than hardcoding. Aliases differ by metadata provider.
metabase