chore: Fix timing issues for flaky tests. (#193)

Author: kinyoklion

packages/shared/sdk-server/__tests__/LDClient.evaluation.test.ts

@@ -1,5 +1,5 @@
 import { LDClientImpl } from '../src';
-import { LDFeatureStore } from '../src/api/subsystems';
+import { LDFeatureStore, LDStreamProcessor } from '../src/api/subsystems';
 import NullUpdateProcessor from '../src/data_sources/NullUpdateProcessor';
 import TestData from '../src/integrations/test_data/TestData';
 import AsyncStoreFacade from '../src/store/AsyncStoreFacade';
@@ -158,6 +158,17 @@ describe('given an offline client', () => {
   });
 });
 
+class InertUpdateProcessor implements LDStreamProcessor {
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  start(fn?: ((err?: any) => void) | undefined) {
+    // Never initialize.
+  }
+
+  stop() {}
+
+  close() {}
+}
+
 describe('given a client and store that are uninitialized', () => {
   let store: LDFeatureStore;
   let client: LDClientImpl;
@@ -178,7 +189,7 @@ describe('given a client and store that are uninitialized', () => {
       'sdk-key',
       basicPlatform,
       {
-        updateProcessor: new NullUpdateProcessor(),
+        updateProcessor: new InertUpdateProcessor(),
         sendEvents: false,
         featureStore: store,
       },

packages/shared/sdk-server/__tests__/LDClientImpl.test.ts

@@ -54,6 +54,7 @@ it('isOffline returns true in offline mode', (done) => {
 
 describe('when waiting for initialization', () => {
   let client: LDClientImpl;
+  let resolve: Function;
 
   beforeEach(() => {
     client = new LDClientImpl(
@@ -62,9 +63,7 @@ describe('when waiting for initialization', () => {
       {
         updateProcessor: {
           start: (fn: (err?: any) => void) => {
-            setTimeout(() => {
-              fn();
-            }, 0);
+            resolve = fn;
           },
           stop: () => {},
           close: () => {},
@@ -81,17 +80,20 @@ describe('when waiting for initialization', () => {
   });
 
   it('resolves when ready', async () => {
+    resolve();
     await client.waitForInitialization();
   });
 
   it('resolves immediately if the client is already ready', async () => {
+    resolve();
     await client.waitForInitialization();
     await client.waitForInitialization();
   });
 
   it('creates only one Promise', async () => {
     const p1 = client.waitForInitialization();
     const p2 = client.waitForInitialization();
+    resolve();
     expect(p2).toBe(p1);
   });
 });