Improve the test coverage of the _get_serialized_fields function

[eloidieme]

Keep a record (copy) of your coverage before you start working on new tests. Furthermore, make sure you add the new tests on a different branch than the one you used for coverage instrumentation. Having identified “weak spots” in coverage, try to improve coverage with additional test cases.

1. Identify the requirements that are tested or untested by the given test suite.
2. Document the requirements (as comments), and use them later as assertions.
3. Create new test cases as needed to improve branch coverage in the given functions. Can you call the function directly? Can you expand on existing tests? Do you have to add additional interfaces to the system (as public methods) to make it possible to set up test data structures?
4. If you have 100 % branch coverage, you can choose other functions or think about path coverage. You may cover all branches in a function, but what does this mean for the combination of branches? Consider the existing tests by hand and check how they cover the branches (in which combinations).

[eloidieme]

• 2 branches are not covered
• 14 branches in total in the function
• Initial coverage: 85%

[eloidieme]

Identified requirements

• Req 1: Serialization of specified fields: the function serializes fields that are explicitly specified in the fields_to_export attribute. This includes handling both when fields_to_export is None (implying all fields should be serialized) and when it is a specific list or mapping of fields to be serialized.
• Req 2: Handling of include_empty parameter: the function respects the include_empty parameter or attribute, determining whether fields not present in the item should be included in the serialization output with a default value.
• Req 3: Default value for missing fields: when fields specified for serialization are not present in the item, the function can assign a default value to these fields in the output.
• Req 4: Correct handling of field names and values in mappings: ensuring that when fields_to_export is a mapping, the function correctly maps item fields to their specified output names and serializes them accordingly. This includes verifying the correct handling of both present and absent fields, according to the include_empty flag.
• Req 5: Behavior when fields_to_export is a mapping and include_empty is false: specifically testing the condition where fields are defined in a mapping (implying a rename is intended during serialization), and ensuring that only those present in the item are included when include_empty is False.

[eloidieme]

• Tested requirements : Reqs 1, 2, 3
• Untested requirements: Reqs 4, 5

[eloidieme]

Now coverage for the function is 92%. Only one non-covered branch left.

[eloidieme]

Finally, coverage is 100% with this second test added.

[eloidieme]

Notes: the function can be called directly in the test suite through the class it belongs to. It was easier to write new tests than to expand on existing tests. I didn't need to add additional interfaces.