Astroquery Testing

Testing in astroquery is a bit more complicated than in other modules since we depend on remote servers to supply data. In order to keep the tests green and fast, we use monkeypatching to test most functions on local copies of the data.

In order to set up testing for any given module, you therefore need to have local copies of the data.

The testing directory structure should look like:

module/tests/__init__.py
module/tests/test_module.py
module/tests/test_module_remote.py
module/tests/setup_package.py
module/tests/data/
module/tests/data/test_data.xml

test_module.py

This file should contain only tests that do not require an internet connection. It also contains the tricky monkeypatching components. At a minimum, monkeypatching requires a few methods that are defined locally in the test file for each module.

Monkeypatching

At a minimum, monkeypatching will require these changes:

class MockResponse(object):

    def __init__(self, content):
        self.content = content

MockResponse is an object intended to have any of the attributes that a normal requests.Response object would have. However, it only needs to implement the methods that are actually used within the tests.

The tricky bits are in the pytest.fixture.

The first little magical function is the patch_x function, where x should either be post or get.

@pytest.fixture
def patch_get(request):
    try:
        mp = request.getfixturevalue("monkeypatch")
    except AttributeError:  # pytest < 3
        mp = request.getfuncargvalue("monkeypatch")
    mp.setattr(requests, 'get', get_mockreturn)
    return mp

This function, when called, changes the requests.get method (i.e., the get method of the requests module) to call the get_mockreturn function, defined below. @pytest.fixture means that, if any function in this test_module.py file accepts patch_get as an argument, patch_get will be called prior to running that function.

get_mockreturn is simple but important: this is where you define a function to return the appropriate data stored in the data/ directory as a readable object within the MockResponse class:

def get_mockreturn(url, params=None, timeout=10):
    filename = data_path(DATA_FILES['votable'])
    content = open(filename, 'r').read()
    return MockResponse(content)

data_path is a simple function that looks for the data directory local to the test_module.py file.

def data_path(filename):
    data_dir = os.path.join(os.path.dirname(__file__), 'data')
    return os.path.join(data_dir, filename)

test_module_remote.py

The remote tests are much easier. Just decorate the test class or test functions with astropy.tests.helper.remote_data.

setup_package.py

This file only needs the get_package_data() function, which will tell setup.py to include the relevant files when installing.

import os

def get_package_data():
    paths_test = [os.path.join('data', '*.xml')]

    return {'astroquery.module.tests': paths_test}