add tests

Author: jhuleatt

packages/remote-config/src/api.ts

@@ -76,7 +76,7 @@ export async function activate(remoteConfig: RemoteConfig): Promise<boolean> {
 /**
  * Configures the Remote Config SDK to talk to a local emulator
  * instead of product.
- * 
+ *
  * Must be called before performing any fetches against production
  * Remote Config.
  *
@@ -85,10 +85,10 @@ export async function activate(remoteConfig: RemoteConfig): Promise<boolean> {
  *
  * @public
  */
- export function connectRemoteConfigEmulator(
+export function connectRemoteConfigEmulator(
   remoteConfig: RemoteConfig,
   url: string
-) {
+): void {
   const rc = getModularInstance(remoteConfig) as RemoteConfigImpl;
 
   // To avoid the footgun of fetching from prod first,

packages/remote-config/test/remote_config.test.ts

@@ -518,4 +518,28 @@ describe('RemoteConfig', () => {
       );
     });
   });
+
+  describe('connectRemoteConfigEmulator', () => {
+    it('changes the remote config API URL', () => {
+      const emulatorUrl = 'http://localhost:9200';
+
+      // init storage as if it had never fetched
+      storageCache.getLastFetchStatus = sinon.stub().returns(undefined);
+
+      api.connectRemoteConfigEmulator(rc, emulatorUrl);
+      expect(window.FIREBASE_REMOTE_CONFIG_URL_BASE === emulatorUrl).to.be.true;
+    });
+
+    it('can not be called if a fetch has already happened', () => {
+      const emulatorUrl = 'http://localhost:9200';
+
+      // init storage as if it had never fetched
+      storageCache.getLastFetchStatus = sinon.stub().returns('success');
+
+      const expectedError = ERROR_FACTORY.create(ErrorCode.ALREADY_FETCHED);
+      expect(() => api.connectRemoteConfigEmulator(rc, emulatorUrl)).to.throw(
+        expectedError.message
+      );
+    });
+  });
 });