planforge-bug-fix-tdd

---

name: planforge-bug-fix-tdd description: Fix a bug using TDD: reproduce with a failing test first, then implement the fix, then verify. Prevents regressions. metadata: author: plan-forge source: .github/prompts/bug-fix-tdd.prompt.md

---

description: "Fix a bug using TDD: reproduce with a failing test first, then implement the fix, then verify. Prevents regressions." agent: "agent" tools: [read, edit, search, execute]

Fix Bug with TDD

Follow the Red-Green-Refactor cycle to fix a bug with a regression test.

Process

Step 1: Understand the Bug

• Read the relevant source files
• Identify the root cause
• Determine which layer the bug is in (Controller / Service / Repository)

Step 2: RED — Write Failing Test

• Create a test that reproduces the exact bug scenario
• Run the test — it MUST fail (proving the bug exists)
• Use [Fact] or [Theory] with descriptive name: {Method}_When{Condition}_Should{Expected}
• Example: CalculateDiscount_WhenNegativePrice_ShouldThrowValidationException

Step 3: GREEN — Implement the Fix

• Write the minimal code to make the test pass
• Fix should be in the correct architectural layer
• Use proper error handling (no empty catch blocks)

Step 4: REFACTOR — Clean Up

• Clean up the fix if needed (extract methods, rename for clarity)
• Verify all existing tests still pass
• Run: dotnet test --no-build

Step 5: Verify

• Run the full test suite to check for regressions
• Confirm the original bug scenario is resolved

Architecture Rules

• NO business logic in controllers — fix in the service layer
• NO direct DB access in services — fix in the repository layer
• ALL async methods must accept CancellationToken
• ALL SQL must use parameterized queries

Reference Files

• Testing instructions
• Error handling
• Architecture principles