test-first-fix

Testing & Quality

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.

QUICK START

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Test-First Fix Workflow

Overview

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

RED: Write and run a failing test
Approval: Get user approval on the specific code change to resolve the issue
GREEN: Implement minimal fix to make test pass
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)

Determine what behavior needs to be tested
Create test file in tests/pytest/ or apps/*/tests/
Write test that fails with current code
Run test and confirm failure with clear error message
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)

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

Step 4: Verify (No Regressions)

Run tests in the same module/category
Run full test suite if risky changes: pytest tests/pytest/
Check for flake8 issues: make test
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.