`unittest.TestCase.assertTrue` is simple enough (the entire implementation is copied below) that there is almost no way for it to fail to raise some kind of exception when its first argument is not truthy:

    def assertTrue(self, expr, msg=None):
        """Check that the expression is true."""
        if not expr:
            msg = self._formatMessage(msg, "%s is not true" % safe_repr(expr))
            raise self.failureException(msg)

This basically hasn't changed in the 19 years since the unittest module was added (though variously at times named `assert_` or `failUnless`), so I'm going to go ahead and close the issue.