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How to speed up iOS simulator tests

Simulator tests take half an hour.

6 min read

Simulator tests take half an hour.

Why it happens

Simulators boot cold, runtimes download at job time, and tests run serially on one device.

How to fix it

  1. Pin to a preinstalled simulator runtime so nothing downloads
  2. Pre-boot the simulator before the test step
  3. Run parallel destinations on one large runner rather than several small ones
  4. Shard by test class with historical timings

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