Cover — Test Suite Generator

Host-neutral workflow. Invoke by skill name (cover). Claude Code slash routing, YAML hook loaders, and .claude/chain live in references/claude-code.md.

Generate comprehensive test suites for existing code with real-service integration testing and automated failure healing.

Note: If disableSkillShellExecution is enabled (CC 2.1.91), the precondition check for vitest/jest won't run. Verify a test runner is installed before proceeding: npx vitest --version or npx jest --version.

Quick Start

cover authentication flow
cover --model=opus payment processing
cover --tier=unit,integration user service
cover --real-services checkout pipeline

Argument Resolution

SCOPE = "$ARGUMENTS"  # e.g., "authentication flow"

# Flag parsing
MODEL_OVERRIDE = None
TIERS = ["unit", "integration", "e2e"]  # default: all three
REAL_SERVICES = False

for token in "$ARGUMENTS".split():
    if token.startswith("--model="):
        MODEL_OVERRIDE = token.split("=", 1)[1]
        SCOPE = SCOPE.replace(token, "").strip()
    elif token.startswith("--tier="):
        TIERS = token.split("=", 1)[1].split(",")
        SCOPE = SCOPE.replace(token, "").strip()
    elif token == "--real-services":
        REAL_SERVICES = True
        SCOPE = SCOPE.replace(token, "").strip()

Step -0.5: Effort-Aware Coverage Scaling (CC 2.1.76, env var since 2.1.120)

Read $CLAUDE_EFFORT (CC 2.1.120+) first; explicit --effort= token wins as override. Default high when CC < 2.1.120 and no flag. Pattern matches assess + explore (#1540). Scale test generation depth:

Values are what you pass as maxIterations in Phase 5. The script clamps to [2, 3] (heal-loop.js), so anything outside that range is coerced, and the final iteration always verifies rather than repairing. There is no 4-iteration mode.

Override: Explicit --tier= flag or user selection overrides /effort downscaling.

Step -1: MCP Probe + Resume Check

# Probe MCPs (parallel):
# memory is alwaysLoad in .mcp.json (CC 2.1.121+, #1541) — probe below kept as fallback for older CC:
ToolSearch(query="select:mcp__memory__search_nodes")
ToolSearch(query="select:mcp__context7__resolve-library-id")

Write(".claude/chain/capabilities.json", {
  "memory": <true if found>,
  "context7": <true if found>,
  "skill": "cover",
  "timestamp": now()
})

# Resume check:
Read(".claude/chain/state.json")
# If exists and skill == "cover": resume from current_phase
# Otherwise: initialize state

Step 0: Scope & Tier Selection

AskUserQuestion(
  questions=[
    {
      "question": "What test tiers should I generate?",
      "header": "Test Tiers",
      "options": [
        {"label": "Full coverage (Recommended)", "description": "Unit + Integration (real services) + E2E"},
        {"label": "Unit + Integration", "description": "Skip E2E, focus on logic and service boundaries"},
        {"label": "Unit only", "description": "Fast isolated tests for business logic"},
        {"label": "E2E only", "description": "Playwright browser tests"}
      ],
      "multiSelect": false
    },
    {
      "question": "Healing strategy for failing tests?",
      "header": "Failure Handling",
      "options": [
        {"label": "Auto-heal (Recommended)", "description": "Fix failing tests up to 3 iterations"},
        {"label": "Generate only", "description": "Write tests, report failures, don't fix"},
        {"label": "Strict", "description": "All tests must pass or abort"}
      ],
      "multiSelect": false
    }
  ]
)

Override TIERS based on selection. Skip this step if --tier= flag was provided.

Finish line. Done means: every generated test runs, the suite is green or each remaining failure is reported with its heal-loop classification, and the coverage report is written. Follow Read("../../shared/rules/long-run-protocol.md"): keep going when a step needs no input from the user, stop and ask only when you can't continue without them or before anything destructive, check each subagent's evidence before accepting it, and mark anything you couldn't confirm with where you looked.

Task Management (MANDATORY)

# 1. Create main task IMMEDIATELY
TaskCreate(subject=f"Cover: {SCOPE}", description="Generate comprehensive test suite with real-service testing", activeForm=f"Generating tests for {SCOPE}")

# 2. Create subtasks for each phase
TaskCreate(subject="Discover scope and detect frameworks", activeForm="Discovering test scope")    # id=2
TaskCreate(subject="Analyze coverage gaps", activeForm="Analyzing coverage gaps")                  # id=3
TaskCreate(subject="Generate tests (parallel per tier)", activeForm="Generating tests")            # id=4
TaskCreate(subject="Execute generated tests", activeForm="Running tests")                          # id=5
TaskCreate(subject="Heal failing tests", activeForm="Healing test failures")                       # id=6
TaskCreate(subject="Generate coverage report", activeForm="Generating report")                     # id=7

# 3. Set dependencies for sequential phases
TaskUpdate(taskId="3", addBlockedBy=["2"])  # Analysis needs discovery first
TaskUpdate(taskId="4", addBlockedBy=["3"])  # Generation needs gap map
TaskUpdate(taskId="5", addBlockedBy=["4"])  # Execution needs generated tests
TaskUpdate(taskId="6", addBlockedBy=["5"])  # Healing needs test results
TaskUpdate(taskId="7", addBlockedBy=["6"])  # Report needs healed suite

# 4. Update status as you progress
TaskUpdate(taskId="2", status="in_progress")  # When starting
TaskUpdate(taskId="2", status="completed")    # When done — repeat for each subtask

6-Phase Workflow

Phase Handoffs

Phase 1: Discovery

Detect the project's test infrastructure and scope the work.

# PARALLEL — all in ONE message:
# 1. Framework detection (hook handles this, but also scan manually)
Grep(pattern="vitest|jest|mocha|playwright|cypress", glob="package.json", output_mode="content")
Grep(pattern="pytest|unittest|hypothesis", glob="pyproject.toml", output_mode="content")
Grep(pattern="pytest|unittest|hypothesis", glob="requirements*.txt", output_mode="content")

# 2. Real-service infrastructure
Glob(pattern="**/docker-compose*.yml")
Glob(pattern="**/testcontainers*")
Grep(pattern="testcontainers", glob="**/package.json", output_mode="content")
Grep(pattern="testcontainers", glob="**/requirements*.txt", output_mode="content")

# 3. Existing test structure
Glob(pattern="**/tests/**/*.test.*")
Glob(pattern="**/tests/**/*.spec.*")
Glob(pattern="**/__tests__/**/*")
Glob(pattern="**/test_*.py")

# 4. Scope files (what to test)
# If SCOPE specified, find matching source files
Grep(pattern=SCOPE, output_mode="files_with_matches")

Real-service decision:

• docker-compose*.yml found → integration tests use real services
• testcontainers in deps → use testcontainers for isolated service instances
• Neither found + --real-services flag → error: "No docker-compose or testcontainers found. Install testcontainers or remove --real-services flag."
• Neither found, no flag → integration tests use mocks (MSW/VCR)

Load real-service detection details: Read("references/real-service-detection.md")

Phase 2: Coverage Analysis

Run existing tests and identify gaps.

# Detect and run coverage command
# TypeScript: npx vitest run --coverage --reporter=json
# Python: pytest --cov=<scope> --cov-report=json
# Go: go test -coverprofile=coverage.out ./...

# Parse coverage output to identify:
# 1. Files with 0% coverage (priority targets)
# 2. Files below threshold (default 70%)
# 3. Uncovered functions/methods
# 4. Untested edge cases (error paths, boundary conditions)

Output coverage baseline to user immediately (progressive output).

Phase 3: Generation (Parallel Agents)

Spawn test-generator agents per tier. Launch ALL in ONE message with run_in_background=true.

Isolation: spawn each tier agent with Agent(isolation="worktree"), one worktree per tier (unit / integration / e2e) so they don't conflict. The subagent bypass of the worktree-isolation guard was fixed in CC 2.1.154 and completed in 2.1.203; ork's floor is >= 2.1.220, so every supported session gets real isolation. Do not create worktrees by hand before spawning.

The new branch's base comes from the worktree.baseRef setting, never from a hardcoded branch name. ork does not set it — a plugin cannot, and no ork settings file carries it. Unless the operator put "baseRef": "head" in .claude/settings.json or ~/.claude/settings.json, CC's default "fresh" applies: every tier agent branches from origin/<default>, unpushed local commits are invisible to it, and tsc fails with "cannot find module" for code you just wrote. Verify the setting before spawning. Full pattern: Read("../chain-patterns/references/worktree-agent-pattern.md")

# Unit tests agent (worktree-isolated)
if "unit" in TIERS:
    Agent(
        subagent_type="ork:test-generator",
        isolation="worktree",
        prompt=f"""Generate unit tests for: {SCOPE}
        Coverage gaps: {gap_map.unit_gaps}
        Framework: {detected_framework}
        Existing tests: {existing_test_files}

        Focus on:
        - AAA pattern (Arrange-Act-Assert)
        - Parametrized tests for multiple inputs
        - MSW/VCR for HTTP mocking (never mock fetch directly)
        - Factory-based test data (FactoryBoy/faker-js)
        - Edge cases: empty input, errors, timeouts, boundary values
        - Target: 90%+ business logic coverage""",
        run_in_background=True,
        max_turns=50,
        model=MODEL_OVERRIDE
    )

# Integration + E2E agents follow the same pattern:
# - subagent_type="ork:test-generator", isolation="worktree", run_in_background=True
# - Integration focus: API endpoints (Supertest/httpx), real DB, contract tests (Pact), Zod schema validation
# - E2E focus: Playwright, semantic locators, Page Object Model, axe-core a11y, visual regression
#
# Special case — emulate (Vercel Labs stateful API emulation):
# When integration tests need GitHub/Stripe/Resend/Okta/etc. emulated
# (HMAC webhooks, parallel port isolation, full config from scratch),
# spawn emulate-engineer instead of test-generator for that tier:
# - subagent_type="ork:emulate-engineer" (same isolation="worktree" form)
# - Pairs with emulate-seed skill for seed YAML patterns

Output each agent's results as soon as it returns — don't wait for all agents.

Focus mode (CC 2.1.101): In focus mode, include the full coverage report (before/after delta, test count per tier, files created) in your final message.

Phase 4: Execution

Run all generated tests and collect results.

# Run test commands per tier (PARALLEL if independent):
# Unit: npx vitest run tests/unit/ OR pytest tests/unit/
# Integration: npx vitest run tests/integration/ OR pytest tests/integration/
# E2E: npx playwright test

# Collect: pass count, fail count, error details, coverage delta

Phase 5: Heal Loop

Do NOT hand-roll the loop. Run the real executor:

Workflow(
  scriptPath="${CLAUDE_SKILL_DIR}/workflows/heal-loop.js",
  args={"testCommand": "<tier test command>", "tier": "unit", "testGlob": "tests/unit/",
        "maxIterations": 3}   # from the effort table above; omitted defaults to 3
)
# One invocation per tier that has failures.

The iteration bound is enforced by the script, not by instruction. heal-loop.js runs a real counted loop clamped to [2, 3]: each iteration spawns a diagnose agent that actually executes the test command and returns structured pass/fail plus the verbatim failure output, then a repair agent that receives that failure text and edits test files only. It exits early the moment the suite is green.

The final iteration diagnoses but does not repair - there would be no run left to verify that repair. So maxIterations: N means N diagnose runs and N-1 repair passes, and the default 3 means 2 repairs. A ceiling of 1 is coerced to 2, since 1 would mean zero repairs.

Every failure is classified into the taxonomy (assertion, import, setup, timeout, stale-selector, type, flaky, plus source-bug), which selects the fix strategy.

The workflow returns status: "healed" or a structured failure (status: "failed", healed: false) carrying remaining_failures, failure_categories, and the per-iteration ledger. Never report a "failed" result as a success: surface the still-failing tests in the Phase 6 report.

Strategy detail (taxonomy table, fix rules, flaky prevention): Read("references/heal-loop-strategy.md")

Boundary: heal fixes TESTS, not source code. If a test fails because the source code has a bug, report it — don't silently fix production code.

Phase 6: Report

Generate coverage report with before/after comparison.

Full report layout (baseline→after table, tests-generated counts, heal iterations, files created, remaining gaps, next-steps commands): Read("references/coverage-report-template.md").

PushNotification on Completion (CC 2.1.110+)

Full cover runs (unit + integration + E2E with heal loop) take 15–45 min. After the Phase 6 report is assembled, call PushNotification(message=f"ork:cover complete — {SCOPE}: {coverage_pct}% coverage · {tests_generated} tests · {heal_loops} heal iters", status="proactive"). Full rule: Read("../chain-patterns/rules/push-notification-on-completion.md").

Coverage Drift Monitor (CC 2.1.71)

Optionally schedule weekly coverage drift detection:

# Guard: Skip cron in headless/CI (CLAUDE_CODE_DISABLE_CRON)
# if env CLAUDE_CODE_DISABLE_CRON is set, run a single check instead
CronCreate(
  schedule="0 2 * * 0",
  prompt="Weekly coverage drift check for {SCOPE}: npm test -- --coverage.
    If coverage >= baseline → CronDelete.
    If coverage drops > 5% → alert with regression details and recommendation."
)

Key Principles

• Output limits (CC 2.1.77+): Opus 4.8 defaults to 64k output tokens (128k upper bound). For large test suites, chunk generation across multiple agent turns if output approaches the limit.
• Partial reads (CC 2.1.144+): Read returns a [PARTIAL view] first page (not an error) on oversized files — re-read with explicit offset/limit so coverage analysis sees the whole file.
• Tests only — never modify production source code, only generate test files
• Real services when available — prefer testcontainers/docker-compose over mocks for integration tests because mock/prod divergence causes silent failures in production
• Parallel generation — spawn one test-generator agent per tier in ONE message
• Heal, don't loop forever — max 3 iterations, then report remaining failures
• Progressive output — show results as each agent completes
• Factory over fixtures — use FactoryBoy/faker-js for test data, not hardcoded values
• Mock at network level — MSW/VCR, never mock fetch/axios directly

Agent Coordination

Context Passing

Each test-generator agent receives: coverage gaps for its tier, test framework config, real-service infrastructure (testcontainers, docker-compose), and fixture patterns from the project.

Monitor + Partial Results (CC 2.1.98)

Use Monitor for streaming test execution output from background agents:

# Stream test suite output in real-time
Bash(command="npm test -- --coverage 2>&1", run_in_background=true)
Monitor(pid=test_task_id)  # Each line → notification

Full pattern reference (until-condition gates, partial-result salvage, TaskOutput vs Monitor decision): Read("../chain-patterns/references/monitor-patterns.md").

Partial results (CC 2.1.98): If a test-generator crashes mid-generation, synthesize what it produced:

for agent_result in test_gen_results:
    if "[PARTIAL RESULT]" in agent_result.output: A `maxTurns` stop is also partial since CC 2.1.246 (summary: "stopped at its N-turn limit (partial result; continue it with SendMessage to the task-id)"); continue that agent with `SendMessage` instead of re-spawning it.
        # Agent crashed — check if it wrote any test files before dying
        partial_tests = Glob(pattern="**/tests/**/*.test.*", path=agent_result.worktree)
        if partial_tests:
            # 6 passing tests from a crashed agent > 0 tests
            # Copy partial tests to main worktree, run them in Phase 4
            for test_file in partial_tests:
                Bash(command=f"cp {test_file} {main_worktree}/{test_file}")
            # Flag as partial in report

SendMessage (Test Healing)

Cross-session replies land in the parent (CC 2.1.248): when a subagent sends SendMessage to another session, the reply is delivered to the parent session's conversation, never to the subagent; a subagent sends and moves on, the parent reads the answer. Cross-session SendMessage / ListAgents also work on Bedrock, Vertex and Foundry and with telemetry disabled (CC 2.1.248).

When a generated test fails, the healer agent can request context from the generator:

SendMessage(to="test-generator-unit", message="Test user_service_test.py:42 fails — TypeError on mock return. What's the expected shape?")

Skill Chain

Standard chain: implement → cover → verify → commit. Use addBlockedBy between each.

Verification Gate

Before claiming coverage is complete, apply: Read("../../shared/rules/verification-gate.md"). Run the coverage report fresh. "Should pass" is not evidence.

Agent Status Protocol

All test-generator agents report using: Read("../../shared/status-protocol.md"). BLOCKED if tests can't be written due to missing interfaces. NEEDS_CONTEXT if test expectations are unclear.

Quality Bar

Done means all of these hold:

• coverage report shows the before→after delta from the actual coverage command output, not an estimate
• every generated test file was executed; final pass/fail counts pasted from the runner
• no production source modified — only test files created; a source bug is reported, never silently patched
• failures healed within the iteration budget (≤3, effort-scaled) or reported explicitly with the remaining-failure count
• each requested tier (unit/integration/e2e) either produced tests or has a stated reason it was skipped

Related Skills

• ork:implement — generates tests during implementation (Phase 5); use cover after for deeper coverage
• ork:verify — grades existing tests 0-10; chain: implement → cover → verify
• testing-unit / testing-integration / testing-e2e — knowledge skills loaded by test-generator agents
• ork:commit — commit generated test files

Session recovery (CC 2.1.108+): After idle periods or interruptions, use /recap to restore conversational context alongside checkpoint-resume state. Enabled by default since CC 2.1.110 (even with telemetry disabled).

References

Load on demand with Read("references/<file>"):

Version: 1.2.0 (April 2026) — $CLAUDE_EFFORT env var as primary effort signal (CC 2.1.120, #1540)