fetchActions tests: Test retry logic with a more representative error.

The fact that this test passes isn't good -- it means a basically
arbitrary, unexpected kind of error will let the retry loop continue
without propagating to `tryFetch`'s caller. Instead, if something
unexpected like that happens, we should fail early (and stop wasting
the user's time) by breaking out of the retry loop and having the
error propagate to the caller.

We plan to fix that logic in a different series of commits, and add
a test case with an error like that. But for now, test that we get
the right behavior with representative inputs.

src/message/__tests__/fetchActions-test.js

@@ -116,13 +116,19 @@ describe('fetchActions', () => {
       jest.runAllTimers();
     });
 
-    test('retries a call, if there is an exception', async () => {
+    test('retries a call if there is a non-client error', async () => {
+      const serverError = new ApiError(500, {
+        code: 'SOME_ERROR_CODE',
+        msg: 'Internal Server Error',
+        result: 'error',
+      });
+
       // fail on first call, succeed second time
       let callCount = 0;
       const thrower = jest.fn(() => {
         callCount++;
         if (callCount === 1) {
-          throw new Error('First run exception');
+          throw serverError;
         }
         return 'hello';
       });
@@ -135,7 +141,7 @@ describe('fetchActions', () => {
       await expect(tryFetch(tryFetchFunc)).resolves.toBe('hello');
 
       expect(tryFetchFunc).toHaveBeenCalledTimes(2);
-      await expect(tryFetchFunc.mock.results[0].value).rejects.toThrow('First run exception');
+      await expect(tryFetchFunc.mock.results[0].value).rejects.toThrow(serverError);
       await expect(tryFetchFunc.mock.results[1].value).resolves.toBe('hello');
 
       jest.runAllTimers();