gstack/ship/sections/test-coverage.md

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## Step 7: Test Coverage Audit

### Shared subagent dispatch

For Steps 7, 8 and 10, use the Agent tool with `run_in_background: false`.
Omitting the flag runs the subagent in the background. The explicit flag waits
for a result while keeping a fresh context. Do not invoke the target as a Skill
or run it inline instead. Inline work is allowed only under that section's
documented fallback, after a failed subagent has stopped.

Dispatch the audit through Agent with `subagent_type: "general-purpose"` and
`run_in_background: false`, using the shared foreground-dispatch rule above.
Wait for its LAST-line JSON before applying the coverage gate.

**Generation allowance:** Maximum 2 generation passes total per invocation.
Count each generation-authorized attempt before dispatch/inline execution, including
the initial audit, failures and zero-test results. Re-entry never resets it.
Two passes already used means no further generation; read-only reassessment uses no pass.

**Subagent prompt:** Supply `<base>`, Step 4's framework/bootstrap decision,
permitted paths/commands, remaining gaps, passes used and generation allowance.
No allowance means audit only; missing permission is not approval. Preserve the
30-path/20-test/2-minute per-test caps.

````text
You are running a ship-workflow test coverage audit. Run `git diff origin/<base>` to include uncommitted tracked changes; also read relevant non-ignored untracked source/tests. Do not commit or push. Perform only this audit; return unresolved user decisions to the parent instead of asking or advancing to another workflow step.

Generation: <allowed|audit-only>; passes used: <N> of 2. Audit-only overrides every generation instruction below.

100% coverage is the goal — every untested path is a path where bugs hide and vibe coding becomes yolo coding. Evaluate what was ACTUALLY coded (from the diff), not what was planned.

### Test Framework Detection

Before analyzing coverage, detect the project's test framework:

1. **Read CLAUDE.md** — look for a `## Testing` section with test command and framework name. If found, use that as the authoritative source.
2. **If CLAUDE.md has no testing section, auto-detect:**

```bash
setopt +o nomatch 2>/dev/null || true  # zsh compat
# Detect project runtime (markers are evidence, not commands to run blind)
[ -f manage.py ] && echo "RUNTIME:python FRAMEWORK:django"
{ [ -f pyproject.toml ] || [ -f pytest.ini ] || [ -f tox.ini ] || [ -f setup.cfg ] || [ -f requirements.txt ]; } && echo "RUNTIME:python"
{ [ -f Gemfile ] || [ -f Rakefile ] || [ -f .rspec ]; } && echo "RUNTIME:ruby"
[ -f package.json ] && echo "RUNTIME:node"
[ -f go.mod ] && echo "RUNTIME:go"
[ -f Cargo.toml ] && echo "RUNTIME:rust"
[ -f pom.xml ] && echo "RUNTIME:jvm BUILD:maven"
{ [ -f build.gradle ] || [ -f build.gradle.kts ]; } && echo "RUNTIME:jvm BUILD:gradle"
# Check for existing test infrastructure — config files, scripts, AND test files
ls jest.config.* vitest.config.* playwright.config.* cypress.config.* .rspec pytest.ini tox.ini phpunit.xml 2>/dev/null
[ -f package.json ] && grep -q '"test"[[:space:]]*:' package.json && echo "SCRIPT:package.json test"
[ -f Makefile ] && grep -qE '^(test|check):' Makefile && echo "TARGET:make test"
git ls-files | grep -cE '(^|/)(tests?|spec|__tests__)/|(^|/)tests?\.py$|(^|/)test_[^/]+\.py$|_test\.(go|py|rb|ts|js|exs)$|\.(test|spec)\.[jt]sx?$|_spec\.rb$|Test\.(java|kt)$' | sed 's/^/TESTFILES:/'
```

3. **If no framework detected:** use the bootstrap decision already made in Step 4; report diagram-only coverage if setup was declined. Do not restart bootstrap from this audit.

**0. Before/after test count:**

```bash
# Count test files before any generation
git ls-files 2>/dev/null | grep -E '(\.test\.|\.spec\.|_test\.|_spec\.)' | wc -l
```

Store this number for the PR body.

**1. Trace every codepath changed** using `git diff origin/<base>`:

Read every changed file. For each one, trace how data flows through the code — don't just list functions, actually follow the execution:

1. **Read the diff.** For each changed file, read the full file (not just the diff hunk) to understand context.
Definition: a **targeted audit** reviews named concrete source/test files or a
branch diff. A **prototype** is existing runnable code referenced by the plan,
not a proposed future component.

When grounded in concrete source and test files, read them in a dedicated tool
call before drawing the diagram. Finish this source read before tracing data
flow in audit item 2 below; map user flows afterward. Do not mix diff, grep,
package/config, git, or commentary into that read; use separate calls for
context. Base the diagram on that read.
2. **Trace data flow.** Starting from each entry point (route handler, exported function, event listener, component render), follow the data through every branch:
   - Where does input come from? (request params, props, database, API call)
   - What transforms it? (validation, mapping, computation)
   - Where does it go? (database write, API response, rendered output, side effect)
   - What can go wrong at each step? (null/undefined, invalid input, network failure, empty collection)
3. **Diagram the execution.** For each changed file, draw an ASCII diagram showing:
   - Every function/method that was added or modified
   - Every conditional branch (if/else, switch, ternary, guard clause, early return)
   - Every error path (try/catch, rescue, error boundary, fallback)
   - Every call to another function (trace into it — does IT have untested branches?)
   - Every edge: what happens with null input? Empty array? Invalid type?

This is the critical step — you're building a map of every line of code that can execute differently based on input. Every branch in this diagram needs a test.

**2. Map user flows, interactions, and error states:**

Code coverage isn't enough — you need to cover how real users interact with the changed code. For each changed feature, think through:

- **User flows:** What sequence of actions does a user take that touches this code? Map the full journey (e.g., "user clicks 'Pay' → form validates → API call → success/failure screen"). Each step in the journey needs a test.
- **Interaction edge cases:** What happens when the user does something unexpected?
  - Double-click/rapid resubmit
  - Navigate away mid-operation (back button, close tab, click another link)
  - Submit with stale data (page sat open for 30 minutes, session expired)
  - Slow connection (API takes 10 seconds — what does the user see?)
  - Concurrent actions (two tabs, same form)
- **Error states the user can see:** For every error the code handles, what does the user actually experience?
  - Is there a clear error message or a silent failure?
  - Can the user recover (retry, go back, fix input) or are they stuck?
  - What happens with no network? With a 500 from the API? With invalid data from the server?
- **Empty/zero/boundary states:** What does the UI show with zero results? With 10,000 results? With a single character input? With maximum-length input?

Add these to your diagram alongside the code branches. A user flow with no test is just as much a gap as an untested if/else.

**3. Check each branch against existing tests:**

Go through your diagram branch by branch — both code paths AND user flows. For each one, search for a test that exercises it:
- Function `processPayment()` → look for `billing.test.ts`, `billing.spec.ts`, `test/billing_test.rb`
- An if/else → look for tests covering BOTH the true AND false path
- An error handler → look for a test that triggers that specific error condition
- A call to `helperFn()` that has its own branches → those branches need tests too
- A user flow → look for an integration or E2E test that walks through the journey
- An interaction edge case → look for a test that simulates the unexpected action

Quality scoring rubric:
- ★★★  Tests behavior with edge cases AND error paths
- ★★   Tests correct behavior, happy path only
- ★    Smoke test / existence check / trivial assertion (e.g., "it renders", "it doesn't throw")

### E2E Test Decision Matrix

When checking each branch, also determine whether a unit test or E2E/integration test is the right tool:

**RECOMMEND E2E (mark as [→E2E] in the diagram):**
- Common user flow spanning 3+ components/services (e.g., signup → verify email → first login)
- Integration point where mocking hides real failures (e.g., API → queue → worker → DB)
- Auth/payment/data-destruction flows — too important to trust unit tests alone

**RECOMMEND EVAL (mark as [→EVAL] in the diagram):**
- Critical LLM call that needs a quality eval (e.g., prompt change → test output still meets quality bar)
- Changes to prompt templates, system instructions, or tool definitions

**STICK WITH UNIT TESTS:**
- Pure function with clear inputs/outputs
- Internal helper with no side effects
- Edge case of a single function (null input, empty array)
- Obscure/rare flow that isn't customer-facing

### REGRESSION RULE (mandatory)

**IRON RULE:** When the coverage audit identifies a REGRESSION — code that previously worked but the diff broke — a regression test is written immediately. No AskUserQuestion. No skipping. Regressions are the highest-priority test because they prove something broke.

A regression is when:
- The diff modifies existing behavior (not new code)
- The existing test suite (if any) doesn't cover the changed path
- The change introduces a new failure mode for existing callers

When uncertain whether a change is a regression, err on the side of writing the test.

**4. Output ASCII coverage diagram:**

For targeted audits, start Test review output with the coverage diagram. In full
plan reviews, put it inside the normal Test review section. Required outputs
keep the final terminal report order.

Include BOTH code paths and user flows in the same diagram. Mark E2E-worthy and eval-worthy paths:

```
CODE PATHS                                            USER FLOWS
[+] src/services/billing.ts                           [+] Payment checkout
  ├── processPayment()                                  ├── [★★★ TESTED] Complete purchase — checkout.e2e.ts:15
  │   ├── [★★★ TESTED] happy + declined + timeout      ├── [GAP] [→E2E] Double-click submit
  │   ├── [GAP]         Network timeout                 └── [GAP]        Navigate away mid-payment
  │   └── [GAP]         Invalid currency
  └── refundPayment()                                 [+] Error states
      ├── [★★  TESTED] Full refund — :89                ├── [★★  TESTED] Card declined message
      └── [★   TESTED] Partial (non-throw only) — :101  └── [GAP]        Network timeout UX

LLM integration: [GAP] [→EVAL] Prompt template change — needs eval test

COVERAGE: 5/13 paths tested (38%)  |  Code paths: 3/5 (60%)  |  User flows: 2/8 (25%)
QUALITY: ★★★:2 ★★:2 ★:1  |  GAPS: 8 (2 E2E, 1 eval)
```

Legend: ★★★ behavior + edge + error  |  ★★ happy path  |  ★ smoke check
[→E2E] = needs integration test  |  [→EVAL] = needs LLM eval

Avoid bare `[ ]` or `[x]` in diagrams unless the block includes
`Legend: [x] tested | [ ] no test`. Prefer `[GAP]`, `[★★ TESTED]`,
`[→E2E]`, `[→EVAL]`; keep user-flow markers off code-path rows.

**Fast path:** All paths covered → "Step 7: All new code paths have test coverage ✓" Continue.

**5. Generate tests for uncovered paths:**

If test framework detected (or bootstrapped in Step 4):
- Prioritize error handlers and edge cases first (happy paths are more likely already tested)
- Read 2-3 existing test files to match conventions exactly
- Generate unit tests. Mock all external dependencies (DB, API, Redis).
- For paths marked [→E2E]: generate integration/E2E tests using the project's E2E framework (Playwright, Cypress, Capybara, etc.)
- For paths marked [→EVAL]: generate eval tests using the project's eval framework, or flag for manual eval if none exists
- Write tests that exercise the specific uncovered path with real assertions
- Run each test. Passes → keep the change and report its path; the parent commits in Step 15.
- Fails → diagnose whether the test/fixture is invalid or a declared product contract is broken. Correct a demonstrated test defect once; preserve a valid red regression and route the reproduced product failure through the parent's fix/approval flow. Never delete or weaken it to manufacture green; retain unresolved coverage in the diagram.

Caps: 30 code paths max, 20 tests generated max (code + user flow combined), 2-min per-test exploration cap.

If no test framework AND user declined bootstrap → diagram only, no generation. Note: "Test generation skipped — no test framework configured."

**Diff is test-only changes:** Return a skipped audit with null coverage, zero gaps, and "No new application code paths to audit."

**6. After-count and coverage summary:**

```bash
# Count test files after generation
git ls-files 2>/dev/null | grep -E '(\.test\.|\.spec\.|_test\.|_spec\.)' | wc -l
```

For PR body: `Tests: {before} → {after} (+{delta} new)`
Coverage line: `Test Coverage Audit: N new code paths. M covered (X%). K tests generated, awaiting parent commit.`

### Test Plan Artifact

After producing the coverage diagram, write a test plan artifact so `/qa` and `/qa-only` can consume it:

```bash
eval "$(~/.claude/skills/gstack/bin/gstack-slug 2>/dev/null)" && mkdir -p ~/.gstack/projects/$SLUG
USER=$(whoami)
DATETIME=$(date +%Y%m%d-%H%M%S)
```

Write to `~/.gstack/projects/{slug}/{user}-{branch}-ship-test-plan-{datetime}.md`:

```markdown
# Test Plan
Generated by /ship on {date}
Branch: {branch}
Repo: {owner/repo}

## Affected Pages/Routes
- {URL path} — {what to test and why}

## Key Interactions to Verify
- {interaction description} on {page}

## Edge Cases
- {edge case} on {page}

## Critical Paths
- {end-to-end flow that must work}
```

After your analysis, output a single JSON object on the LAST LINE of your response (no other text after it):
{"coverage_pct":N,"gaps":N,"diagram":"<full markdown coverage diagram for PR body>","tests_added":["path",...]}
Use null for an undetermined or skipped coverage percentage, not zero. Include every remaining gap in the diagram so the parent can target a second pass.
````

**Parent processing:**

1. Read the subagent's final output. Parse the LAST line as JSON.
2. Store `coverage_pct` (for Step 20 metrics), `gaps` (user summary), `tests_added` (for the commit).
3. Embed `diagram` verbatim in the PR body's `## Test Coverage` section (Step 19).
4. Print a one-line summary: `Coverage: {coverage_pct}%, {gaps} gaps. {tests_added.length} tests added.`

**Audit failure:** On failure, invalid JSON or no completion after ~10 minutes,
stop the child and confirm it stopped before running the same audit inline.
Fallback recovers the audit; it does not pass or bypass the coverage gate.
Apply that gate to the recovered results, including its undetermined-percentage
and test-only rules. Preserve partial results as incomplete, not passing coverage.


**7. Coverage gate:**

The parent owns this gate, including after inline fallback. Generated tests stay uncommitted until Step 15. Use Step 7's remaining generation allowance; supply it and the remaining gaps to the same audit prompt. At the cap, omit A and recommend stopping; the listed risk choices remain available.

Before proceeding, check CLAUDE.md for a `## Test Coverage` section with `Minimum:` and `Target:` fields. If found, use those percentages. Otherwise use defaults: Minimum = 60%, Target = 80%.

Using the coverage percentage from the diagram in substep 4 (the `COVERAGE: X/Y (Z%)` line):

- **>= target:** Pass. "Coverage gate: PASS ({X}%)." Continue.
- **>= minimum, < target:** Use AskUserQuestion:
  - "AI-assessed coverage is {X}%. {N} code paths are untested. Target is {target}%."
  - RECOMMENDATION: Choose A because untested code paths are where production bugs hide.
  - Options:
    A) Generate more tests for remaining gaps (recommended)
    B) Ship anyway — I accept the coverage risk
    C) These paths don't need tests — mark as intentionally uncovered
  - If A and allowance remains: dispatch one generation pass, then re-evaluate here. At the cap, offer only B/C or stop; never another generation pass.
  - If B: Continue. Include in PR body: "Coverage gate: {X}% — user accepted risk."
  - If C: Continue. Include in PR body: "Coverage gate: {X}% — {N} paths intentionally uncovered."

- **< minimum:** Use AskUserQuestion:
  - "AI-assessed coverage is critically low ({X}%). {N} of {M} code paths have no tests. Minimum threshold is {minimum}%."
  - RECOMMENDATION: Choose A because less than {minimum}% means more code is untested than tested.
  - Options:
    A) Generate tests for remaining gaps (recommended)
    B) Override — ship with low coverage (I understand the risk)
  - If A and allowance remains: dispatch one generation pass, then re-evaluate here. At the cap, offer only B or stop; never another generation pass.
  - If B: Continue. Include in PR body: "Coverage gate: OVERRIDDEN at {X}%."

**Coverage percentage undetermined:** If the coverage diagram doesn't produce a clear numeric percentage (ambiguous output, parse error), **skip the gate** with: "Coverage gate: could not determine percentage — skipping." Do not default to 0% or block.

**Test-only diffs:** Skip the gate (same as the existing fast-path).

**100% coverage:** "Coverage gate: PASS (100%)." Continue.

---