This is a simple example Flask application demonstrating how to combine a Flask application with some testing including coverage analysis. To see this in action do the following:

$ git clone https://github.com/allanderek/flask-coverage-example.git
$ cd flask-coverage-example
$ . setup.fish # or source setup.sh
$ python manage.py test

You should then be able to look in the htmlcov directory to see the source marked-up with all the lines ran. Specially open the file htmlcov/app_main_py.html.

To see an example of a missing line, locate the lines:

try:
    check_fraction(50, 100, '50 of 100 is 50%')
    check_fraction(20, 30, '20 of 30 is 66%')
    check_fraction(50, 10, 'Invalid: Fraction greater than Total')
    check_fraction(0, 0, '0 of 0 is 0%')

Comment out some of them, say the bottom two, re-run python manage.py test and reload htmlcov/app_main_py.html in your browser.