Print custom string upon unittest failure

Question

I am using a for loop to iterate through a config file and pass variables within to a unit test.

for module in config:
        for testcase in config[module]:
            data = config[dict.keys(config)[0]][testcase]['foo']
            test_foo(self, data)

The problem with this method is the failures can be similar and are printed out at the end of testing. So there is no way to tell which variable it was that failed, only that n variables failed the test. Is there a way to print a custom string upon failure which would include the failed variable? Or perhaps there is even a better way to test the variables in my config file?

Answer 1

You can provide custom string in assert* method:

self.assertEqual('foo'.upper(), 'FOO', 'custom message')

This custom message will be printed on test failure