This commit better aligns the mock client implementations used in
ServiceWorker tests (and the associated typings) with the actual
implementations (and the official TypeScript typings). This allows
verifying the ServiceWorker behavior in a slightly more realistic
environment.
This is in preparation of switching from our custom typings to the
official TypeScript typings (`lib.webworker.d.ts`).
PR Close#42736
In the ServiceWorker tests, we use mock implementations of the various
client APIs that the ServiceWorker interacts with. Previously, these
mock implementations were defined in the `testing/scope.ts` file. This
added several extra classes to a file that already contains a few,
making it harder to maintain.
Therefore, this commit moves these mock client classes to a separate
`testing/clients.ts` file.
PR Close#42736
