Behavioral Regression Tests

Write regression tests that (1) are portable across platforms where behavior is shared and (2) are “behaviorally decisive,” meaning they must fail if the real logic is removed.

Apply:

• Use broad cfg gates for shared behavior (e.g., #[cfg(unix)]) rather than narrow OS-specific gates in core modules.
• Shape fixtures so the expected state transition is not satisfied by index coincidences or incidental setup. If your code must “reconcile” selection/focus after deletion or shifting, pick a scenario where indices change and the reconciliation block is required.

Example (portability + decisive setup):

#[cfg(unix)]
#[test]
fn preserves_selection_after_close_requiring_reconciliation() {
    // Arrange: 3 workspaces so the survivor index shifts
    // e.g., [background (only tab), middle, active (selected)]

    // Act: close background's last tab

    // Assert: selected workspace is updated by reconciliation logic,
    // and the test would fail if focus/selection reconciliation were removed.
}

This standard prevents flaky/overly restrictive platform gating and ensures regression tests actually guard the behavior you care about.