Adding in NoMissingUnitTest linter rule

[cmgoffena13]

I'm having trouble fleshing out the test due to the path having to point to the example project. Since I have to trigger the pytest from the root it is trying to find the /tests directory in the root rather than the example project root. Any help on resolving the path issue would be appreciated so I can finish the test. (EDIT: Figured out how to switch the contexts, let me know if there's anything that needs adjustment!)

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[cmgoffena13]

@VaggelisD @georgesittas - alright, took my first swing at it if either of you want to take a look.

1. Added in a property method to ModelTestMetadata to get model_name from the body easily
2. Added model_test_metadata and models_with_tests to be added when a project loads so a Set of model names is only calculated once upon load.
3. Added self._model_test_metadata and self._models_with_tests to the context and Context::load() brings it in from loaded projects.
4. Made sure the Context::test() utilizes the eagerly loaded test metadata instead of lazily loading it again

I did surface models_with_tests as a property in the Context to access for the linter rule.

Let me know if you want me to change anything!

[georgesittas]

Btw, let's make sure that we track calls to load_model_tests and refactor as needed. For example, in magics.py, I think we should be able to skip that call since we already have the loaded context which contains all tests. Another example is in lsp/context.py.

[georgesittas]

These iterations over test_meta look costly. Can we store a mapping test_name -> test_meta instead of keeping everything in a list and having to walk it every time?

[cmgoffena13]

Just pushed, I added in two dictionaries, one for the fully qualified names and another for the Paths so they're just lookups. Calculated once in the context.

[georgesittas]

Thanks for addressing the comments @cmgoffena13. I'll take another look soon.