Question 1

How do I mock multiple modules in one Elixir test?

Accepted Answer

Use the `with_mocks` macro to define a list of modules and their mock functions, as shown in the README example with Map and String modules, allowing concurrent mocking in a single test block.

Question 2

Mock vs Mox: which is better for Elixir testing?

Accepted Answer

Mock is simpler for quick module mocking with macros, ideal for basic tests, while Mox is better for defining explicit behaviors and contracts, especially in larger codebases with dependency injection.

Question 3

Can I mock internal function calls with the Mock library?

Accepted Answer

No, Mock does not support mocking internal calls; you must refactor code to use fully qualified names like `__MODULE__.function()` or `Module.function()`, as explained in the 'NOT SUPPORTED' section.

Question 4

How to assert a function was called with specific arguments in Mock?

Accepted Answer

Use `assert_called` with exact values or pattern matchers like `:meck.is/1` for advanced validation, as demonstrated in the README with struct matching and custom logic.

Question 5

Is Mock compatible with async ExUnit tests?

Accepted Answer

No, you must set `async: false` in test modules using Mock to avoid conflicts, as mocking has global effects that prevent parallel test execution.

Question 6

How to mock a function that returns different values on repeated calls?

Accepted Answer

Use the `in_series` option in the mock definition to specify a series of return values for consecutive calls, though the README cautions this is only for rare stateful scenarios.

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