Step 3 of the simplification review. Tests only, no production code changes. - `TestEvents.kt`: defaulted `testEvent` / `allDayEvent` / `timedEvent` / `testDetail` builders replace the full `EventInstance(...)` / `EventDetail(...)` spellings and the per-file `allDay`/`timed` helpers. Helpers with test-specific titles, colours or zones stay as one-line wrappers, so every built event is unchanged. - `TestRepositories.kt`: `testDataStore` / `testPrefs` / `testSettings` / `testRepository` plus a JUnit 5 `MainDispatcherExtension` replace the repeated DataStore, repository and setMain/resetMain wiring. Same 1302 tests before and after; widget tests untouched. Co-authored-by: Jean-Luc Makiola <business@jeanlucmakiola.de> Reviewed-on: https://codeberg.org/jlmakiola/calendula/pulls/408