---

name: check-test-coverage description: Standard procedure for checking test coverage using pytest-cov in the airline-discount-ml project.

Checking Test Coverage

When the user wants to check test coverage, use pytest with the coverage plugin to generate detailed reports.

Prerequisites

1. pytest-cov must be installed:

   Copycd airline-discount-ml
   pip install pytest-cov
   

2. Tests must exist in the tests/ directory

Standard Coverage Procedures

Coverage for All Tests

Copycd airline-discount-ml
pytest --cov=src tests/ --cov-report=term-missing
# or
make test-cov

Coverage for Specific Module

Copycd airline-discount-ml
pytest --cov=src.models tests/models/ --cov-report=term-missing
pytest --cov=src.data tests/data/ --cov-report=term-missing
pytest --cov=src.training tests/training/ --cov-report=term-missing

Coverage for Specific File

Copycd airline-discount-ml
pytest --cov=src.models.discount_predictor tests/models/test_discount_predictor.py --cov-report=term-missing

Coverage Report Formats

Terminal Report (Default)

Shows coverage percentage per file:

Copypytest --cov=src tests/ --cov-report=term

Output:

Copy---------- coverage: platform linux, python 3.11.9 -----------
Name                                    Stmts   Miss  Cover
-----------------------------------------------------------
src/__init__.py                             2      0   100%
src/models/__init__.py                      3      0   100%
src/models/discount_predictor.py           85      5    94%
src/models/passenger_profiler.py           42      2    95%
-----------------------------------------------------------
TOTAL                                     132      7    95%

Terminal with Missing Lines

Shows which lines are not covered:

Copypytest --cov=src tests/ --cov-report=term-missing

Output:

CopyName                                    Stmts   Miss  Cover   Missing
---------------------------------------------------------------------
src/models/discount_predictor.py           85      5    94%   45-47, 62, 78
src/models/passenger_profiler.py           42      2    95%   23, 67

HTML Report (Interactive)

Generates detailed HTML coverage report:

Copypytest --cov=src tests/ --cov-report=html

View report:

Copy# Open in browser
open htmlcov/index.html          # macOS
xdg-open htmlcov/index.html      # Linux
start htmlcov/index.html         # Windows

XML Report (CI/CD)

For continuous integration tools:

Copypytest --cov=src tests/ --cov-report=xml

Generates coverage.xml for tools like CodeCov, Coveralls.

Multiple Report Formats

Combine multiple report types:

Copypytest --cov=src tests/ --cov-report=term-missing --cov-report=html --cov-report=xml

Coverage Thresholds

Fail Build if Coverage Too Low

Copypytest --cov=src tests/ --cov-fail-under=80

Returns non-zero exit code if coverage < 80%.

Check Minimum Coverage Per File

Copypytest --cov=src tests/ --cov-report=term-missing --cov-fail-under=90

Advanced Coverage Options

Branch Coverage

Check both line and branch coverage:

Copypytest --cov=src tests/ --cov-branch --cov-report=term-missing

Shows coverage of conditional branches (if/else, try/except):

CopyName                              Stmts   Miss Branch BrPart  Cover
-------------------------------------------------------------------
src/models/discount_predictor.py     85      5     24      3    92%

Focus on New Code

Only show coverage for modified files:

Copypytest --cov=src --cov-report=term-missing $(git diff --name-only HEAD | grep '\.py$' | sed 's/^/tests\//; s/src/test/; s/\.py$/_test.py/')

Exclude Patterns

Exclude specific files or directories:

Copypytest --cov=src --cov-report=term-missing --cov-config=.coveragerc tests/

Create .coveragerc:

Copy[run]
omit = 
    */tests/*
    */migrations/*
    */__init__.py

Expected Output

High Coverage (Good)

Copy---------- coverage: platform linux, python 3.11.9 -----------
Name                                    Stmts   Miss  Cover   Missing
---------------------------------------------------------------------
src/models/discount_predictor.py           85      2    98%   45, 62
src/models/passenger_profiler.py           42      0   100%
src/training/train.py                      63      4    94%   23-26
-------------------------------------------------------------------
TOTAL                                     190      6    97%

Low Coverage (Needs Attention)

Copy---------- coverage: platform linux, python 3.11.9 -----------
Name                                    Stmts   Miss  Cover   Missing
---------------------------------------------------------------------
src/models/discount_predictor.py           85     35    59%   12-45, 62-78, 92-105
-------------------------------------------------------------------
TOTAL                                      85     35    59%

Coverage Targets

Project Standards

• Models: >95% line coverage, >85% branch coverage
• Data: >90% line coverage (use mocks for DB)
• Training: >85% line coverage
• Agents: >80% line coverage
• Overall: >90% line coverage

Untestable Code

Mark code that shouldn't be covered:

Copydef debug_only_function():  # pragma: no cover
    """Only used for manual debugging."""
    import pdb; pdb.set_trace()

Troubleshooting

No Coverage Data Collected

Solution: Ensure pytest-cov is installed and tests are actually running:

Copypip install pytest-cov
pytest --cov=src tests/ -v  # Verbose to see test execution

Coverage Shows 0% for All Files

Solution: Check that module paths are correct:

Copy# Wrong (from project root)
pytest --cov=airline-discount-ml/src tests/

# Right
cd airline-discount-ml
pytest --cov=src tests/

HTML Report Not Generating

Solution: Ensure output directory is writable:

Copyrm -rf htmlcov/
pytest --cov=src tests/ --cov-report=html
ls -la htmlcov/  # Verify files created

Integration with Make

Add to Makefile:

Copytest-cov:
	pytest --cov=src tests/ --cov-report=term-missing --cov-report=html

test-cov-fail:
	pytest --cov=src tests/ --cov-fail-under=90

Run:

Copymake test-cov
make test-cov-fail

Quick Reference