Allow to Mock Resource in testing

i would to mock read's like `read("env:MY_CUSTOM_ENV")` for a specific test case/(or test file at least)

Context: I have a Global Config object which reads env variables and i would like to define them in a test file.

Mocking Resources could be a way i think

No file, test, or entry point is named. Start by examining how read("env:MY_CUSTOM_ENV") is resolved and how a Global Config object reads environment variables. Done means a test case or test file can provide mocked resource values and verify the resulting configuration.

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