How can I use itertools to simplify this nested for loop?

Question

How can I use itertools to simplify this nested for loop?

# pytest file:

def get_test_cases():

    with open("file_path.yml", "r", encoding="utf-8") as index_file:
        data = yaml.safe_load(index_file)

    for vendor_dict in data:
        for vendor_name, class_list in vendor_dict.items():
            for class_dict in class_list:
                for class_name, method_list in class_dict.items():
                    for method_dict in method_list:
                        for function, test_list in method_dict.items():
                            for test_case in test_list:
                                yield vendor_name, class_name, function, test_case

@pytest.mark.parametrize("iteration", get_test_cases())
def test_network(iteration, monkeypatch):
    """Performs pytest using info provided from test case"""

    (vendor_name, class_name, function, test_case) = iteration

    # Use data above to perform pytest
    # Code omitted

Sample Data is in YAML:

# YAML file:

- cisco:
    - CiscoClass:
        - get_interface_stats:
            - test_description: "test interface stats"
              function_input: "Gig1/1/1"
              expected_output: "show interfaces Gig1/1/1"

- juniper:
    - JuniperClass:
        - get_vlan_info: 
            - test_description: "test get_vlan_info"
              function_input: "10"
              expected_output: "show vlan 10"

Explanation

The YAML file contains parameters uses for building test cases. We have a block of test cases for Cisco, and other test cases for Juniper. So the structure is this vendor --> name of class --> function --> test case data

Function get_test_cases in my pytest file will load the YAML file contents, and then iterates through the contents, and yield data for each test case. Function test_network consumes this data, and performs the actual testing.

I am trying to find an alternative to the nested for loops so that I can raise my pylint rating... if this is even possible.

Answer 1

You could try the following to make it a bit compacter:

def testcases(data, level=0):
    if level == 3:
        for case in data:
            yield (case,)
    else:
        for record in data:
            for name in record:
                for case in testcases(record[name], level + 1):
                    yield (name,) + case

or

def testcases(data, level=0):
    if level == 6:
        for case in data:
            yield (case,)
    elif level % 2 == 0:
        for record in data:
            yield from testcases(record, level + 1)
    else:
        for name, records in data.items():
            for case in testcases(records, level + 1):
                yield (name,) + case

and then

def get_test_cases():
    with open("file_path.yml", "r", encoding="utf-8") as index_file:
        data = yaml.safe_load(index_file)
    yield from testcases(data)

With your sample file this

for case in get_test_cases():
    print(case)

does produce

('cisco', 'CiscoClass', 'get_interface_stats', {'test_description': 'test interface stats', 'function_input': 'Gig1/1/1', 'expected_output': 'show interfaces Gig1/1/1'})
('juniper', 'JuniperClass', 'get_vlan_info', {'test_description': 'test get_vlan_info', 'function_input': '10', 'expected_output': 'show vlan 10'})