Using pytest.mark.parametrize to read from list to generate tests dynamically

Question

I have a function which reads yaml file and generates test iterations as a list of dictionaries like below:

Iterations = lib_iterations()

print Iterations

Iterations = [{'mode':1,'format':5,'ip':'192.16.1.103'},
            {'mode':2,'format':6,'ip':'192.16.1.104'},
            {'mode':2,'format':8,'ip':'192.16.1.110'},
            {'mode':6,'format':2,'ip':'192.16.1.105'},
            {'mode':5,'format':7,'ip':'192.16.1.102'},
            {'mode':4,'format':2,'ip':'192.16.1.101'}]

I need to be able to pass this set to pytest.mark.parametrize to generate a test for each iteration/each row in the list.

I do not know the dictionary keys before I call the function lib_iterations which generates this list of dictionaries.

Any ideas on how to do this?

Answer 1

If your problem is how to pass Iterations list to pytest parametrize decorator, then you can do this:

@pytest.mark.parametrize('testdata', [i for i in Iterations])

If content of Iterations is unknown in the test module then you can use pytest_generate_tests hook. In that hook function you can load the yaml file and pass its content to metafunc.parametrize:

import yaml

def pytest_generate_tests(metafunc):
    if 'testdata' in metafunc.fixturenames:
        with open("testdata.yml", 'r') as f:
            Iterations = yaml.load(f)
            metafunc.parametrize('testdata', [i for i in Iterations])

The test function using this fixture:

def test_it(testdata):
    print testdata