Improving Performance at Compile Time
Explore techniques to improve Elixir application performance during testing by using compile-time configuration with Application.compile_env/3. Understand how to optimize external service calls by leveraging Mox.stub_with/2 to combine doubles and real modules for flexible tests. Learn to balance test isolation with performance in integration scenarios.
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The patterns we previously discussed are powerful and flexible, and they let us have fine-tuned control over testing interactions with external services. However, there’s still one principle we’re going against.We’re introducing a runtime call to decide which double to use in production code. That is, every time we call the rain?/2 function, we’ll call Application.get_env/3 (which is essentially a read from an ETS table) to get the double module we want to use.
In this case, the performance hit is negligible compared to the cost of the HTTP ...