Mobile Test Pyramid: Coverage vs. Cost vs. Flakiness

The "testing pyramid" is the standard mental model for a mobile app's automated test suite: many fast, cheap unit tests at the base, fewer integration tests in the middle, and a thin layer of slow, expensive UI/end-to-end tests at the top. This simulator turns that model into a real 3D pyramid built from individually rendered test cases and lets you reshape it — drag the unit, integration and UI test counts and the parallel CI worker pool, then run the pipeline. Live readouts compute the pipeline's parallelised wall-clock time, the probability a real regression escapes to production given each tier's diminishing-returns detection curve, and the expected number (and probability) of flaky false failures per run using a Poisson model of each tier's non-determinism rate. Invert the pyramid — heavy on slow UI tests, thin on unit tests — and watch pipeline time explode while flaky-failure risk climbs, exactly the trade-off real mobile CI/CD teams have to manage.