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Property-Based Testing with PropEr in Elixir

Adjusting the Model: Fixing the Issue

Explore how to diagnose and resolve state mismatches in circuit breaker testing by adjusting your state machine model. Understand failure threshold nuances and update model transitions to align with real system behavior for more accurate stateful property tests.

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Finding the issue

The first step in determining any stateful failure is to figure out which failing sequence caused the problem. Shrinking does most of the job, but we still have to extract meaning out of it. We have something similar to the following:

Test failure output
Test failure output

This creates a sequence of events and state transitions as follows:

At least, that’s the expectation from the history we have. However, we expected to see {error, {circuit_breaker, _}} for the last error call since ...