writing_tests.md

Writing new tests

The test suite is intended to run a binary and compare its standard output, standard error and return value against provided values. This is implemented using Python's unittest module and thus all test files are Python files.

The simplest test has the following structure:

# -*- coding: utf-8 -*-

import system_tests


class GoodTestName(metaclass=system_tests.CaseMeta):

    filename = "$data_path/test_file"
    commands = ["$exiv2 $filename", "$exiv2 $filename" + '_2']
    stdout = [""] * 2
    stderr = ["""$exiv2_exception_msg $filename:
$kerFailedToReadImageData
"""] * 2
    retval = [1] * 2

The test suite will run the provided commands in commands and compare them to the output in stdout and stderr and it will compare the return values.

The strings after a $ are variables either defined in this test's class or are taken from the suite's configuration file (see doc.md for a complete explanation).

When creating new tests, follow roughly these steps:

1. Choose an appropriate subdirectory where the test belongs. If none fits create a new one and put an empty __init__.py file there.

2. Create a new file with a name matching test_*.py. Copy the class definition from the above example and choose an appropriate class name.

3. Run the test suite via python3 runner.py and ensure that your test case is actually run! Either run the suite with the -v option which will output all test cases that were run or simply add an error and check if errors occur.