Tools: How I Reduced My Test Suite by 72% Using TestIQ

The Problem: AI Generates Tests Fast, But Redundantly ## The Scale of the Problem ## Why Text Similarity Doesn't Work ## The Solution: Coverage Analysis ## Types of Duplicates Detected ## How It Works ## 1. Install TestIQ ## 2. Collect Coverage Data ## 3. Analyze for Duplicates ## 4. Compare Tests Visually ## Real-World Results ## Calculator Example (AI-Generated) ## Production Django Application ## CI/CD Integration ## Configuration ## Try It Yourself ## Key Takeaways ## What's Next? AI coding assistants (GitHub Copilot, Cursor, ChatGPT) are game-changers for test generation. But there's a critical issue: they don't check if tests duplicate existing coverage. Here's what happened when I let AI generate tests for a simple calculator: Different function names, slightly different formatting, but identical coverage. Each test executes the exact same code paths. I analyzed the complete calculator test suite: Only 15 unique tests were actually needed. That's a 72% redundancy rate! 🤯 My first instinct: "Just compare the test code!" But these tests look different yet do the same thing: Text similarity would rate these as "different" - but they execute identical code paths. I built TestIQ to analyze execution patterns instead of text: Exact Duplicates - Identical coverage Subset Duplicates - One test covered by another Similar Tests - Significant overlap (configurable) TestIQ includes a built-in pytest plugin that tracks per-test coverage. No configuration needed! Get an interactive HTML report showing: Click any test pair to see a split-screen comparison: Prevent duplicate tests from merging: Builds fail if duplicates are detected. No manual review needed! Fine-tune duplicate detection: See full configuration docs. TestIQ includes a demo with the actual AI-generated calculator example: This generates and opens an HTML report showing all 207 redundancies in 54 tests. TestIQ is open source (MIT) and actively developed: Contributions welcome! Issues, PRs, and feedback appreciated. Have you dealt with test suite bloat from AI-generated code? Share your experiences in the comments! 👇 Want to try it? pip install testiq && testiq demo Templates let you quickly answer FAQs or store snippets for re-use. Are you sure you want to hide this comment? It will become hidden in your post, but will still be visible via the comment's permalink. Hide child comments as well For further actions, you may consider blocking this person and/or reporting abuse COMMAND_BLOCK: # AI cheerfully created all 5 of these: def test_addition(): assert Calculator().add(2, 3) == 5 def test_add_numbers(): assert Calculator().add(2, 3) == 5 def test_sum_calculation(): assert Calculator().add(2, 3) == 5 def test_calculate_sum(): assert Calculator().add(2, 3) == 5 def test_basic_addition(): assert Calculator().add(2, 3) == 5 Enter fullscreen mode Exit fullscreen mode COMMAND_BLOCK: # AI cheerfully created all 5 of these: def test_addition(): assert Calculator().add(2, 3) == 5 def test_add_numbers(): assert Calculator().add(2, 3) == 5 def test_sum_calculation(): assert Calculator().add(2, 3) == 5 def test_calculate_sum(): assert Calculator().add(2, 3) == 5 def test_basic_addition(): assert Calculator().add(2, 3) == 5 COMMAND_BLOCK: # AI cheerfully created all 5 of these: def test_addition(): assert Calculator().add(2, 3) == 5 def test_add_numbers(): assert Calculator().add(2, 3) == 5 def test_sum_calculation(): assert Calculator().add(2, 3) == 5 def test_calculate_sum(): assert Calculator().add(2, 3) == 5 def test_basic_addition(): assert Calculator().add(2, 3) == 5 COMMAND_BLOCK: # Test 1: Simple assertion def test_addition(): result = Calculator().add(2, 3) assert result == 5 # Test 2: Different style, same coverage def test_sum(): calc = Calculator() total = calc.add(2, 3) self.assertEqual(total, 5) # Test 3: One-liner, same coverage def test_calc_add(): assert Calculator().add(2, 3) == 5 Enter fullscreen mode Exit fullscreen mode COMMAND_BLOCK: # Test 1: Simple assertion def test_addition(): result = Calculator().add(2, 3) assert result == 5 # Test 2: Different style, same coverage def test_sum(): calc = Calculator() total = calc.add(2, 3) self.assertEqual(total, 5) # Test 3: One-liner, same coverage def test_calc_add(): assert Calculator().add(2, 3) == 5 COMMAND_BLOCK: # Test 1: Simple assertion def test_addition(): result = Calculator().add(2, 3) assert result == 5 # Test 2: Different style, same coverage def test_sum(): calc = Calculator() total = calc.add(2, 3) self.assertEqual(total, 5) # Test 3: One-liner, same coverage def test_calc_add(): assert Calculator().add(2, 3) == 5 CODE_BLOCK: test_addition → lines [9, 11, 12] test_add_numbers → lines [9, 11, 12] ❌ DUPLICATE Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: test_addition → lines [9, 11, 12] test_add_numbers → lines [9, 11, 12] ❌ DUPLICATE CODE_BLOCK: test_addition → lines [9, 11, 12] test_add_numbers → lines [9, 11, 12] ❌ DUPLICATE CODE_BLOCK: test_basic_add → lines [9, 11] test_comprehensive_add → lines [9, 11, 15, 20, 25] ⚠️ SUBSET Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: test_basic_add → lines [9, 11] test_comprehensive_add → lines [9, 11, 15, 20, 25] ⚠️ SUBSET CODE_BLOCK: test_basic_add → lines [9, 11] test_comprehensive_add → lines [9, 11, 15, 20, 25] ⚠️ SUBSET CODE_BLOCK: test_addition → lines [9, 11, 15] test_subtraction → lines [9, 11, 20] ⚠️ 66% similar Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: test_addition → lines [9, 11, 15] test_subtraction → lines [9, 11, 20] ⚠️ 66% similar CODE_BLOCK: test_addition → lines [9, 11, 15] test_subtraction → lines [9, 11, 20] ⚠️ 66% similar COMMAND_BLOCK: pip install testiq Enter fullscreen mode Exit fullscreen mode COMMAND_BLOCK: pip install testiq COMMAND_BLOCK: pip install testiq CODE_BLOCK: pytest --testiq-output=coverage.json Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: pytest --testiq-output=coverage.json CODE_BLOCK: pytest --testiq-output=coverage.json CODE_BLOCK: testiq analyze coverage.json --format html --output report.html Enter fullscreen mode Exit fullscreen mode CODE_BLOCK: testiq analyze coverage.json --format html --output report.html CODE_BLOCK: testiq analyze coverage.json --format html --output report.html COMMAND_BLOCK: # .github/workflows/test-quality.yml name: Test Quality Check on: [pull_request] jobs: check-duplicates: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - name: Set up Python uses: actions/setup-python@v5 with: python-version: '3.11' - name: Install dependencies run: | pip install testiq pytest pytest-cov pip install -r requirements.txt - name: Collect coverage run: pytest --testiq-output=coverage.json - name: Check for duplicates run: | testiq analyze coverage.json \ --quality-gate \ --max-duplicates 0 \ --format html \ --output testiq-report.html - name: Upload report if: always() uses: actions/upload-artifact@v4 with: name: testiq-report path: testiq-report.html Enter fullscreen mode Exit fullscreen mode COMMAND_BLOCK: # .github/workflows/test-quality.yml name: Test Quality Check on: [pull_request] jobs: check-duplicates: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - name: Set up Python uses: actions/setup-python@v5 with: python-version: '3.11' - name: Install dependencies run: | pip install testiq pytest pytest-cov pip install -r requirements.txt - name: Collect coverage run: pytest --testiq-output=coverage.json - name: Check for duplicates run: | testiq analyze coverage.json \ --quality-gate \ --max-duplicates 0 \ --format html \ --output testiq-report.html - name: Upload report if: always() uses: actions/upload-artifact@v4 with: name: testiq-report path: testiq-report.html COMMAND_BLOCK: # .github/workflows/test-quality.yml name: Test Quality Check on: [pull_request] jobs: check-duplicates: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - name: Set up Python uses: actions/setup-python@v5 with: python-version: '3.11' - name: Install dependencies run: | pip install testiq pytest pytest-cov pip install -r requirements.txt - name: Collect coverage run: pytest --testiq-output=coverage.json - name: Check for duplicates run: | testiq analyze coverage.json \ --quality-gate \ --max-duplicates 0 \ --format html \ --output testiq-report.html - name: Upload report if: always() uses: actions/upload-artifact@v4 with: name: testiq-report path: testiq-report.html COMMAND_BLOCK: # .testiq.toml [analysis] similarity_threshold = 0.3 # 30% overlap = similar min_coverage_lines = 5 # Ignore trivial tests max_results = 100 # Limit report size [reporting] format = "html" split_similar_threshold = 0.5 # Split similar tests [performance] enable_parallel = true max_workers = 8 Enter fullscreen mode Exit fullscreen mode COMMAND_BLOCK: # .testiq.toml [analysis] similarity_threshold = 0.3 # 30% overlap = similar min_coverage_lines = 5 # Ignore trivial tests max_results = 100 # Limit report size [reporting] format = "html" split_similar_threshold = 0.5 # Split similar tests [performance] enable_parallel = true max_workers = 8 COMMAND_BLOCK: # .testiq.toml [analysis] similarity_threshold = 0.3 # 30% overlap = similar min_coverage_lines = 5 # Ignore trivial tests max_results = 100 # Limit report size [reporting] format = "html" split_similar_threshold = 0.5 # Split similar tests [performance] enable_parallel = true max_workers = 8 COMMAND_BLOCK: # .testiq.yaml analysis: similarity_threshold: 0.3 min_coverage_lines: 5 reporting: format: html performance: enable_parallel: true Enter fullscreen mode Exit fullscreen mode COMMAND_BLOCK: # .testiq.yaml analysis: similarity_threshold: 0.3 min_coverage_lines: 5 reporting: format: html performance: enable_parallel: true COMMAND_BLOCK: # .testiq.yaml analysis: similarity_threshold: 0.3 min_coverage_lines: 5 reporting: format: html performance: enable_parallel: true COMMAND_BLOCK: pip install testiq testiq demo Enter fullscreen mode Exit fullscreen mode COMMAND_BLOCK: pip install testiq testiq demo COMMAND_BLOCK: pip install testiq testiq demo - 54 tests generated by AI - 39 exact duplicates (same coverage) - 168 subset duplicates (tests completely covered by others) - 45 similar test pairs (significant overlap) - Collect coverage - Track which lines each test executes - Compare patterns - Find tests with identical/overlapping coverage - Visualize results - Interactive HTML reports with side-by-side comparison - All duplicate test relationships - Side-by-side coverage comparison - Recommended actions (keep/remove) - Before: 54 tests, ~10 minute CI run - After: 15 tests, ~3 minute CI run - Savings: 70% faster CI, 39 fewer tests to maintain - Coverage: 100% maintained ✅ - Before: 847 tests - After: 612 tests (removed 235 duplicates) - Savings: 28% faster CI runs - Coverage: No reduction ✅ - AI tools generate tests fast - but don't check for coverage duplication - Coverage analysis beats text similarity - catches duplicates that look different - Significant reduction possible - 72% in AI-generated suites, 28% in production - No coverage loss - Remove duplicates while maintaining 100% coverage - CI/CD ready - Block PRs with duplicate tests automatically - GitHub: https://github.com/pydevtools/TestIQ - PyPI: https://pypi.org/project/testiq/ - Documentation: https://github.com/pydevtools/TestIQ/tree/main/README.md