[Tutor] Do not understand why test is running.

[Peter Otten]

boB Stepp wrote:

> On Thu, Aug 20, 2015 at 10:13 PM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>> On Thu, Aug 20, 2015 at 09:01:50PM -0500, boB Stepp wrote:
>>
>>
>>> import unittest
>>>
>>> # import modules to be tested:
>>> import mcm.db.manager
>>>
>>> class ManagerTestCase(unittest.TestCase):
>>>     def setUp(self):
>>>         # Insert setup code here...
>>>         pass
>>>
>>>     def test_open_db(self):
>>>         pass
>>>
>>>     def tearDown(self):
>>>         # Insert tear-down code here...
>>>         pass
>>>
>>> #if __name__ == "__main__":
>>> #    unittest.main()
>>
>>
>> The two commented out lines at the end would, if uncommented, run
>> unittest.main() if and only if you are running this specific module as a
>> thread. In other words, if you were to run:
>>
>> python /path/to/the/test.py
>>
>> then __name__ would be set to the string "__main__", the if clause would
>> trigger, and unittest.main() would run. Since those lines are commented
>> out, that cannot happen.
> 
> Okay, I uncommented those two lines and got:
> 
> E:\Projects\mcm>py -m unittest ./mcm/test/db/test_manager.py
> Traceback (most recent call last):
>   File "C:\Python34\lib\runpy.py", line 170, in _run_module_as_main
>     "__main__", mod_spec)
>   File "C:\Python34\lib\runpy.py", line 85, in _run_code
>     exec(code, run_globals)
>   File "C:\Python34\lib\unittest\__main__.py", line 18, in <module>
>     main(module=None)
>   File "C:\Python34\lib\unittest\main.py", line 92, in __init__
>     self.parseArgs(argv)
>   File "C:\Python34\lib\unittest\main.py", line 139, in parseArgs
>     self.createTests()
>   File "C:\Python34\lib\unittest\main.py", line 146, in createTests
>     self.module)
>   File "C:\Python34\lib\unittest\loader.py", line 146, in
>   loadTestsFromNames
>     suites = [self.loadTestsFromName(name, module) for name in names]
>   File "C:\Python34\lib\unittest\loader.py", line 146, in <listcomp>
>     suites = [self.loadTestsFromName(name, module) for name in names]
>   File "C:\Python34\lib\unittest\loader.py", line 105, in
>   loadTestsFromName
>     module = __import__('.'.join(parts_copy))
> ValueError: Empty module name
> 
> Now what?

Yea, breaking things is an art form ;)

If you want to trigger the 

if __name__ == "__main__": ...

you have to invoke the test script with

py ./mcm/test/db/test_manager.py

the same way you would invoke any other script.

py -m unittest <more args>

runs the unittest module which is free to do what it wants with its 
arguments. Let's see:

$ python3 -m unittest -h
usage: python3 -m unittest [-h] [-v] [-q] [-f] [-c] [-b] [tests [tests ...]]

positional arguments:
  tests           a list of any number of test modules, classes and test 
methods.

optional arguments:
  -h, --help      show this help message and exit
  -v, --verbose   Verbose output
  -q, --quiet     Quiet output
  -f, --failfast  Stop on first fail or error
  -c, --catch     Catch ctrl-C and display results so far
  -b, --buffer    Buffer stdout and stderr during tests

Examples:
  python3 -m unittest test_module               - run tests from test_module
  python3 -m unittest module.TestClass          - run tests from 
module.TestClass
  python3 -m unittest module.Class.test_method  - run specified test method

usage: python3 -m unittest discover [-h] [-v] [-q] [-f] [-c] [-b] [-s START] 
[-p PATTERN] [-t TOP]

optional arguments:
  -h, --help            show this help message and exit
  -v, --verbose         Verbose output
  -q, --quiet           Quiet output
  -f, --failfast        Stop on first fail or error
  -c, --catch           Catch ctrl-C and display results so far
  -b, --buffer          Buffer stdout and stderr during tests
  -s START, --start-directory START
                        Directory to start discovery ('.' default)
  -p PATTERN, --pattern PATTERN
                        Pattern to match tests ('test*.py' default)
  -t TOP, --top-level-directory TOP
                        Top level directory of project (defaults to start 
directory)

For test discovery all test modules must be importable from the top level 
directory of the project.

Did you spot the relevant lines? It's

"""
positional arguments:
  tests           a list of any number of test modules, classes and test 
methods.
"""

"""
or
  python3 -m unittest module.TestClass          - run tests from 
module.TestClass
"""

Unfortunately the implementation is dumb enough to interpret

./mcm/test/db/test_manager.py

as class "/mcm/test/db/test_manager.py" in module "". You get the same 
complaint as for ".foo" (or just "."):

$ python3 -m unittest .foo
Traceback (most recent call last):
  File "/usr/lib/python3.4/runpy.py", line 170, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.4/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/usr/lib/python3.4/unittest/__main__.py", line 18, in <module>
    main(module=None)
  File "/usr/lib/python3.4/unittest/main.py", line 92, in __init__
    self.parseArgs(argv)
  File "/usr/lib/python3.4/unittest/main.py", line 139, in parseArgs
    self.createTests()
  File "/usr/lib/python3.4/unittest/main.py", line 146, in createTests
    self.module)
  File "/usr/lib/python3.4/unittest/loader.py", line 146, in 
loadTestsFromNames
    suites = [self.loadTestsFromName(name, module) for name in names]
  File "/usr/lib/python3.4/unittest/loader.py", line 146, in <listcomp>
    suites = [self.loadTestsFromName(name, module) for name in names]
  File "/usr/lib/python3.4/unittest/loader.py", line 105, in 
loadTestsFromName
    module = __import__('.'.join(parts_copy))
ValueError: Empty module name