Agent skill

dev-tdd

Test-driven development workflow. Auto-detects backend (.NET) and frontend (Angular/TypeScript) from project files. Loops RED→GREEN→REFACTOR cycles until 80%+ coverage is reached. Filter with "dotnet" or "angular" to target one stack. Use when the user says "TDD", "write tests first", "test-driven", or invokes /dev-tdd.

View SKILL.md on GitHub Repository
Stars 163
Forks 31

Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/dev-tdd-eriklieben-agentic-dev-workflow

SKILL.md

TDD — Unified Entry Point

Routes to the appropriate backend and/or frontend TDD skill, then drives RED→GREEN→REFACTOR cycles until the coverage target is met.

Step 1: Detect Stack

  1. Explicit filter — if the user passed dotnet or angular, use that stack
  2. Context from the feature — if the feature description mentions API/endpoint/aggregate → .NET, if it mentions component/page/signal → Angular
  3. Project detection:
    • .NET: any *.csproj, *.sln file exists
    • Angular: angular.json or package.json with @angular/core exists
  4. workflow.json fallback:
    • type: "api" or type: "library" → .NET
    • type: "frontend" → Angular

Unlike verification/dependency, TDD typically targets one stack at a time — a feature is usually backend or frontend, not both. If both are detected and no filter given, ask the user which stack this feature targets.

Step 2: Plan Test Cases

Before writing any code, analyze the feature and propose test cases:

Feature: Profile email verification

  Test Cases
  ──────────
  1. VerifyEmail_WithCorrectCode_ShouldSucceedAndSetEmail
  2. VerifyEmail_WithExpiredCode_ShouldFail
  3. VerifyEmail_WithWrongCode_ShouldFail
  4. VerifyEmail_WhenAlreadyVerified_ShouldReturnAlreadyVerified
  5. VerifyEmail_WithNullCode_ShouldThrowValidation

  ───────────────────────────────────────────────
  Proceed?  [y]es  [e]dit list  [a]dd more tests

Wait for user input. This ensures alignment on what to test before writing anything.

Step 3: TDD Loop

Read the appropriate sub-skill for patterns and conventions:

  • .NET: .claude/skills/dev-tdd-backend/SKILL.md
  • Angular: .claude/skills/dev-tdd-frontend/SKILL.md

Then loop through each test case:

For each test case:

RED — Write a failing test

Write the test following the sub-skill's conventions (naming, AAA pattern, etc.). Run it to confirm it fails:

  [1/5] VerifyEmail_WithCorrectCode_ShouldSucceedAndSetEmail
  RED   ✗ test fails (method not implemented) — expected

GREEN — Write minimal code to pass

Implement just enough production code to make the test pass. Run the test again:

  GREEN ✓ test passes

REFACTOR — Improve while green

Clean up the implementation if needed. Run tests to confirm still passing.

  REFACTOR ✓ tests still green

After each test case, show progress:

  Progress
  ────────
  ✓ 1. VerifyEmail_WithCorrectCode_ShouldSucceedAndSetEmail
  ✓ 2. VerifyEmail_WithExpiredCode_ShouldFail
  ▸ 3. VerifyEmail_WithWrongCode_ShouldFail          ← next
  · 4. VerifyEmail_WhenAlreadyVerified_ShouldReturnAlreadyVerified
  · 5. VerifyEmail_WithNullCode_ShouldThrowValidation

  Tests: 2/5 done  |  All passing
  ──────────────────────────────────────
  [c]ontinue  [s]kip to coverage check  [q]uit

Continue to next test case unless user intervenes.

Step 4: Coverage Check

After all planned test cases are done, run coverage:

bash
# .NET
dotnet test --collect:"XPlat Code Coverage" --results-directory ./TestResults

# Angular
npx vitest run --coverage

Present the results:

  Coverage Report
  ───────────────
  Overall:        74%  (target: 80%)
  ProfileAggregate:  68%  ← below target
  EmailService:      82%  ✓
  VerifyEndpoint:    71%  ← below target

  Uncovered areas in ProfileAggregate:
  - Line 42-48: error path when stream is empty
  - Line 63-67: concurrent verification guard

  Uncovered areas in VerifyEndpoint:
  - Line 28-35: authorization failure path

  ────────────────────────────────────────
  Add tests for uncovered areas?  [y]es  [p]ick  [s]kip

Step 5: Coverage Loop

If coverage is below 80% and user chose y or p:

  1. Identify the uncovered code paths
  2. Propose additional test cases for them
  3. Run more RED→GREEN→REFACTOR cycles
  4. Re-check coverage
  5. Repeat until 80%+ or user skips
  Additional Test Cases (for coverage)
  ─────────────────────────────────────
  6. VerifyEmail_WhenStreamEmpty_ShouldThrowAggregateNotFound
  7. VerifyEmail_WhenConcurrentVerification_ShouldFailWithConflict
  8. VerifyEndpoint_WithUnauthorized_ShouldReturn401

  ───────────────────────────────────
  Proceed?  [y]es  [p]ick  [s]kip

After each round, re-check coverage:

  Coverage: 74% → 83%  ✓ target met

  Result: 8 tests, all passing, 83% coverage

Step 6: Summary

  TDD Complete
  ────────────
  Feature:   Profile email verification
  Stack:     .NET (xUnit + NSubstitute)
  Tests:     8 written, 8 passing
  Coverage:  83% (target: 80% ✓)
  Files:
    new  tests/Api.Tests/Domain/ProfileVerifyEmailTests.cs
    mod  src/Domain/Aggregates/Profile.cs
    mod  src/Api/Endpoints/ProfileEndpoints.cs

Flags

Flag Behavior
dotnet Use .NET TDD workflow
angular Use Angular TDD workflow
--target N Override coverage target (default: 80)
(feature description) What to build test-first

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