Quick and dirty test assertion counter for Python tests (pytest)

count-test-assertions.py

#!/usr/bin/env python

# pytest provides no mechanism for counting the number of assertions in tests.
#
# This seems like useful information, and this script provides a *reasonable*
# method to get a count.
#
# Since it's simply counting occurances of the string 'assert', it's not
# guaranteed to be fully accurate, but given that a true assert statement
# usually only has one 'assert' string per line, and given that in a test
# file, it would be unusual to have the string 'assert' that is not actually
# an assertion, this approach should still give pretty solid data.
#
# USAGE:
# 
# 1. Drop it in the main pytest 'tests' directory
# 2. Make it executable
# 3. Run without arguments to get total assertion count
# 4. Run with the '-h' argument for help

import os

DEFAULT_TEST_DIRECTORY = os.path.dirname(os.path.realpath(__file__))


def count_asserts_in_file(file_path, debug):
    with open(file_path, 'r') as file:
        count = file.read().count('assert')
    if debug:
        print(f"{file_path}: {count} asserts")
    return count


def count_asserts_in_directory(directory_path, debug):
    total_asserts = 0
    for root, dirs, files in os.walk(directory_path):
        for file in files:
            if file.startswith('test_') and file.endswith('.py'):
                total_asserts += count_asserts_in_file(os.path.join(root, file), debug)
    return total_asserts


if __name__ == "__main__":
    import argparse
    parser = argparse.ArgumentParser(description="Count the number of 'assert' statements in test files.")
    parser.add_argument('directory', metavar='DIR', type=str, nargs='?', default=DEFAULT_TEST_DIRECTORY,
                        help='the directory to analyze (default: %(default)s)')
    parser.add_argument('--debug', action='store_true', help='Print the number of asserts for each file')
    args = parser.parse_args()
    directory_path = args.directory
    debug = args.debug
    total_asserts = count_asserts_in_directory(directory_path, debug)
    print(f"Total asserts in {directory_path}: {total_asserts}")