<purpose>
Generate unit and E2E tests for a completed phase based on its SUMMARY.md, CONTEXT.md, and implementation. Classifies each changed file into TDD (unit), E2E (browser), or Skip categories, presents a test plan for user approval, then generates tests following RED-GREEN conventions.

Users currently hand-craft `/gsd-quick` prompts for test generation after each phase. This workflow standardizes the process with proper classification, quality gates, and gap reporting.
</purpose>

<required_reading>
Read all files referenced by the invoking prompt's execution_context before starting.
</required_reading>

<process>

<step name="parse_arguments">
Parse `$ARGUMENTS` for:
- Phase number (integer, decimal, or letter-suffix) → store as `$PHASE_ARG`
- Remaining text after phase number → store as `$EXTRA_INSTRUCTIONS` (optional)

Example: `/gsd-add-tests 12 focus on edge cases` → `$PHASE_ARG=12`, `$EXTRA_INSTRUCTIONS="focus on edge cases"`

If no phase argument provided:

```
ERROR: Phase number required
Usage: /gsd-add-tests <phase> [additional instructions]
Example: /gsd-add-tests 12
Example: /gsd-add-tests 12 focus on edge cases in the pricing module
```

Exit.
</step>

<step name="init_context">
Load phase operation context:

```bash
INIT=$(node ".agent/get-shit-done/bin/gsd-tools.cjs" init phase-op "${PHASE_ARG}")
if [[ "$INIT" == @file:* ]]; then INIT=$(cat "${INIT#@file:}"); fi
```

Extract from init JSON: `phase_dir`, `phase_number`, `phase_name`.

Verify the phase directory exists. If not:
```
ERROR: Phase directory not found for phase ${PHASE_ARG}
Ensure the phase exists in .planning/phases/
```
Exit.

Read the phase artifacts (in order of priority):
1. `${phase_dir}/*-SUMMARY.md` — what was implemented, files changed
2. `${phase_dir}/CONTEXT.md` — acceptance criteria, decisions
3. `${phase_dir}/*-VERIFICATION.md` — user-verified scenarios (if UAT was done)

If no SUMMARY.md exists:
```
ERROR: No SUMMARY.md found for phase ${PHASE_ARG}
This command works on completed phases. Run /gsd-execute-phase first.
```
Exit.

Present banner:
```
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 GSD ► ADD TESTS — Phase ${phase_number}: ${phase_name}
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
```
</step>

<step name="analyze_implementation">
Extract the list of files modified by the phase from SUMMARY.md ("Files Changed" or equivalent section).

For each file, classify into one of three categories:

| Category | Criteria | Test Type |
|----------|----------|-----------|
| **TDD** | Pure functions where `expect(fn(input)).toBe(output)` is writable | Unit tests |
| **E2E** | UI behavior verifiable by browser automation | Playwright/E2E tests |
| **Skip** | Not meaningfully testable or already covered | None |

**TDD classification — apply when:**
- Business logic: calculations, pricing, tax rules, validation
- Data transformations: mapping, filtering, aggregation, formatting
- Parsers: CSV, JSON, XML, custom format parsing
- Validators: input validation, schema validation, business rules
- State machines: status transitions, workflow steps
- Utilities: string manipulation, date handling, number formatting

**E2E classification — apply when:**
- Keyboard shortcuts: key bindings, modifier keys, chord sequences
- Navigation: page transitions, routing, breadcrumbs, back/forward
- Form interactions: submit, validation errors, field focus, autocomplete
- Selection: row selection, multi-select, shift-click ranges
- Drag and drop: reordering, moving between containers
- Modal dialogs: open, close, confirm, cancel
- Data grids: sorting, filtering, inline editing, column resize

**Skip classification — apply when:**
- UI layout/styling: CSS classes, visual appearance, responsive breakpoints
- Configuration: config files, environment variables, feature flags
- Glue code: dependency injection setup, middleware registration, routing tables
- Migrations: database migrations, schema changes
- Simple CRUD: basic create/read/update/delete with no business logic
- Type definitions: records, DTOs, interfaces with no logic

Read each file to verify classification. Don't classify based on filename alone.
</step>

<step name="present_classification">
Present the classification to the user for confirmation before proceeding:

```
AskUserQuestion(
  header: "Test Classification",
  question: |
    ## Files classified for testing

    ### TDD (Unit Tests) — {N} files
    {list of files with brief reason}

    ### E2E (Browser Tests) — {M} files
    {list of files with brief reason}

    ### Skip — {K} files
    {list of files with brief reason}

    {if $EXTRA_INSTRUCTIONS: "Additional instructions: ${EXTRA_INSTRUCTIONS}"}

    How would you like to proceed?
  options:
    - "Approve and generate test plan"
    - "Adjust classification (I'll specify changes)"
    - "Cancel"
)
```

If user selects "Adjust classification": apply their changes and re-present.
If user selects "Cancel": exit gracefully.
</step>

<step name="discover_test_structure">
Before generating the test plan, discover the project's existing test structure:

```bash
# Find existing test directories
find . -type d -name "*test*" -o -name "*spec*" -o -name "*__tests__*" 2>/dev/null | head -20
# Find existing test files for convention matching
find . -type f \( -name "*.test.*" -o -name "*.spec.*" -o -name "*Tests.fs" -o -name "*Test.fs" \) 2>/dev/null | head -20
# Check for test runners
ls package.json *.sln 2>/dev/null || true
```

Identify:
- Test directory structure (where unit tests live, where E2E tests live)
- Naming conventions (`.test.ts`, `.spec.ts`, `*Tests.fs`, etc.)
- Test runner commands (how to execute unit tests, how to execute E2E tests)
- Test framework (xUnit, NUnit, Jest, Playwright, etc.)

If test structure is ambiguous, ask the user:
```
AskUserQuestion(
  header: "Test Structure",
  question: "I found multiple test locations. Where should I create tests?",
  options: [list discovered locations]
)
```
</step>

<step name="generate_test_plan">
For each approved file, create a detailed test plan.

**For TDD files**, plan tests following RED-GREEN-REFACTOR:
1. Identify testable functions/methods in the file
2. For each function: list input scenarios, expected outputs, edge cases
3. Note: since code already exists, tests may pass immediately — that's OK, but verify they test the RIGHT behavior

**For E2E files**, plan tests following RED-GREEN gates:
1. Identify user scenarios from CONTEXT.md/VERIFICATION.md
2. For each scenario: describe the user action, expected outcome, assertions
3. Note: RED gate means confirming the test would fail if the feature were broken

Present the complete test plan:

```
AskUserQuestion(
  header: "Test Plan",
  question: |
    ## Test Generation Plan

    ### Unit Tests ({N} tests across {M} files)
    {for each file: test file path, list of test cases}

    ### E2E Tests ({P} tests across {Q} files)
    {for each file: test file path, list of test scenarios}

    ### Test Commands
    - Unit: {discovered test command}
    - E2E: {discovered e2e command}

    Ready to generate?
  options:
    - "Generate all"
    - "Cherry-pick (I'll specify which)"
    - "Adjust plan"
)
```

If "Cherry-pick": ask user which tests to include.
If "Adjust plan": apply changes and re-present.
</step>

<step name="execute_tdd_generation">
For each approved TDD test:

1. **Create test file** following discovered project conventions (directory, naming, imports)

2. **Write test** with clear arrange/act/assert structure:
   ```
   // Arrange — set up inputs and expected outputs
   // Act — call the function under test
   // Assert — verify the output matches expectations
   ```

3. **Run the test**:
   ```bash
   {discovered test command}
   ```

4. **Evaluate result:**
   - **Test passes**: Good — the implementation satisfies the test. Verify the test checks meaningful behavior (not just that it compiles).
   - **Test fails with assertion error**: This may be a genuine bug discovered by the test. Flag it:
     ```
     ⚠️ Potential bug found: {test name}
     Expected: {expected}
     Actual: {actual}
     File: {implementation file}
     ```
     Do NOT fix the implementation — this is a test-generation command, not a fix command. Record the finding.
   - **Test fails with error (import, syntax, etc.)**: This is a test error. Fix the test and re-run.
</step>

<step name="execute_e2e_generation">
For each approved E2E test:

1. **Check for existing tests** covering the same scenario:
   ```bash
   grep -r "{scenario keyword}" {e2e test directory} 2>/dev/null || true
   ```
   If found, extend rather than duplicate.

2. **Create test file** targeting the user scenario from CONTEXT.md/VERIFICATION.md

3. **Run the E2E test**:
   ```bash
   {discovered e2e command}
   ```

4. **Evaluate result:**
   - **GREEN (passes)**: Record success
   - **RED (fails)**: Determine if it's a test issue or a genuine application bug. Flag bugs:
     ```
     ⚠️ E2E failure: {test name}
     Scenario: {description}
     Error: {error message}
     ```
   - **Cannot run**: Report blocker. Do NOT mark as complete.
     ```
     🛑 E2E blocker: {reason tests cannot run}
     ```

**No-skip rule:** If E2E tests cannot execute (missing dependencies, environment issues), report the blocker and mark the test as incomplete. Never mark success without actually running the test.
</step>

<step name="summary_and_commit">
Create a test coverage report and present to user:

```
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 GSD ► TEST GENERATION COMPLETE
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

## Results

| Category | Generated | Passing | Failing | Blocked |
|----------|-----------|---------|---------|---------|
| Unit     | {N}       | {n1}    | {n2}    | {n3}    |
| E2E      | {M}       | {m1}    | {m2}    | {m3}    |

## Files Created/Modified
{list of test files with paths}

## Coverage Gaps
{areas that couldn't be tested and why}

## Bugs Discovered
{any assertion failures that indicate implementation bugs}
```

Record test generation in project state:
```bash
node ".agent/get-shit-done/bin/gsd-tools.cjs" state-snapshot
```

If there are passing tests to commit:

```bash
git add {test files}
git commit -m "test(phase-${phase_number}): add unit and E2E tests from add-tests command"
```

Present next steps:

```
---

## ▶ Next Up

{if bugs discovered:}
**Fix discovered bugs:** `/gsd-quick fix the {N} test failures discovered in phase ${phase_number}`

{if blocked tests:}
**Resolve test blockers:** {description of what's needed}

{otherwise:}
**All tests passing!** Phase ${phase_number} is fully tested.

---

**Also available:**
- `/gsd-add-tests {next_phase}` — test another phase
- `/gsd-verify-work {phase_number}` — run UAT verification

---
```
</step>

</process>

<success_criteria>
- [ ] Phase artifacts loaded (SUMMARY.md, CONTEXT.md, optionally VERIFICATION.md)
- [ ] All changed files classified into TDD/E2E/Skip categories
- [ ] Classification presented to user and approved
- [ ] Project test structure discovered (directories, conventions, runners)
- [ ] Test plan presented to user and approved
- [ ] TDD tests generated with arrange/act/assert structure
- [ ] E2E tests generated targeting user scenarios
- [ ] All tests executed — no untested tests marked as passing
- [ ] Bugs discovered by tests flagged (not fixed)
- [ ] Test files committed with proper message
- [ ] Coverage gaps documented
- [ ] Next steps presented to user
</success_criteria>
