Currently if TestBed detects that TestBed.overrideModule was used for module X, transitive scopes are recalculated recursively for all modules that X imports and previously calculated data (stored in cache) is ignored. This behavior was introduced in https://github.com/angular/angular/pull/33787 to fix stale transitive scopes issue (cache was not updated if module overrides are present).
The perf issue comes from a "diamond" problem, where module X is overridden which imports modules A and B, which both import module C. Under previous logic, module C gets its transitive deps recomputed multiple times, during the recompute for both A and B. For deep graphs and big common/shared modules this can be super costly.
This commit updates the logic to recalculate ransitive scopes for the overridden module, while keeping previously calculated scopes of other modules untouched.
PR Close#35454
0a1a989fa9