fix: assertFails for storage read/write requests (firebase#5086)

Fixes Issue 4 of firebase#5086

packages/rules-unit-testing/src/api/index.ts

@@ -698,7 +698,9 @@ export function assertFails(pr: Promise<any>): any {
         errCode === 'permission-denied' ||
         errCode === 'permission_denied' ||
         errMessage.indexOf('permission_denied') >= 0 ||
-        errMessage.indexOf('permission denied') >= 0;
+        errMessage.indexOf('permission denied') >= 0 ||   
+        // Storage permission errors contain message: (storage/unauthorized)
+        errMessage.indexOf('unauthorized') >= 0;
 
       if (!isPermissionDenied) {
         return Promise.reject(

packages/rules-unit-testing/test/database.test.ts

@@ -153,6 +153,31 @@ describe('Testing Module Tests', function () {
       .catch(() => {});
   });
 
+  it('assertFails() if message contains unauthorized', async function () {
+    const success = Promise.resolve('success');
+    const permissionDenied = Promise.reject({
+      message: 'User does not have permission to access \'file\'. (storage/unauthorized)'
+    });
+    const otherFailure = Promise.reject('failure');
+    await firebase
+      .assertFails(success)
+      .then(() => {
+        throw new Error('Expected success to fail.');
+      })
+      .catch(() => {});
+
+    await firebase.assertFails(permissionDenied).catch(() => {
+      throw new Error('Expected permissionDenied to succeed.');
+    });
+
+    await firebase
+      .assertFails(otherFailure)
+      .then(() => {
+        throw new Error('Expected otherFailure to fail.');
+      })
+      .catch(() => {});
+  });
+
   it('discoverEmulators() finds all running emulators', async () => {
     const options = await firebase.discoverEmulators();