test-first-fix

name	test-first-fix
description	Use when: implementing bug fixes or features with RED-GREEN-REFACTOR. Priority order: get user approval before implementation, then apply minimal changes, then run regression checks.

Test-First Fix Workflow

Overview

This skill implements the RED-GREEN-REFACTOR workflow for bug fixes and features in pyTermTk:

1. RED: Write and run a failing test
2. Approval: Get user approval on the specific code change to resolve the issue
3. GREEN: Implement minimal fix to make test pass
4. Verify: Run broader tests to ensure no regressions

When to Use

• Fixing bugs in existing widgets or core functionality
• Implementing new features with clear test requirements
• Making changes that need verification before merging

Workflow

Step 1: RED Phase (Write Failing Test)

1. Determine what behavior needs to be tested
2. Create test file in tests/pytest/ or apps/*/tests/
3. Write test that fails with current code
4. Run test and confirm failure with clear error message
5. Share the failing output with user

Example:

def test_textedit_follow_mode():
    """TextEdit should follow cursor in follow mode"""
    widget = TTkTextEdit(followMode=True)
    widget.setText("Line 1\nLine 2\nLine 3")
    widget.setCursorPosition(2, 0)
    assert widget.viewportTopLine() == 2  # Should scroll to show cursor

Step 2: Approval Gate

STOP — Do not proceed without explicit user approval.

Ask user:

• "The test fails because [reason]. I'll fix it by [approach]. Approve?"
• Wait for explicit approval before coding the fix

This prevents wasted work if the approach is wrong.

Step 3: GREEN Phase (Minimal Fix)

1. Implement the smallest code change that makes the test pass
2. Prefer simple solutions over comprehensive ones
3. Run the failing test → should now pass
4. Confirm no other changes needed

Step 4: Verify (No Regressions)

1. Run tests in the same module/category
2. Run full test suite if risky changes: pytest tests/pytest/
3. Check for flake8 issues: make test
4. Confirm all tests pass

Important Rules

• ❌ Never write test and implementation in same step
• ❌ Never implement before user approval
• ✅ Always ask for approval after RED phase
• ✅ Always verify no regressions after GREEN phase
• ✅ Prefer minimal changes (don't refactor unless needed)

Example Session

USER: Fix the TextEdit cursor position bug

AGENT (RED PHASE):
  Created test at tests/pytest/widgets/textedit/test_cursor_bug.py
  Test fails: AssertionError: expected 5, got 3
  
  Root cause: setCursorPosition() doesn't update internal position correctly
  
  Fix approach: Modify _cursorPos update in setCursorPosition()
  
  Approve?

USER: Yes, go ahead

AGENT (GREEN PHASE):
  [Implements fix]
  Test now passes ✓
  
AGENT (VERIFY PHASE):
  Running surrounding tests...
  ✓ 47 tests passed
  ✓ 0 tests failed
  
Done! Fix is ready.