Minor cleanup to $firebaseAuth code and docs

docs/migration/1XX-to-2XX.md

@@ -24,24 +24,25 @@ for details on how to upgrade to the Firebase `3.x.x` SDK.
 
 ## `$firebaseAuth` Method Renames / Signature Changes
 
-Initializing `$firebaseAuth` has changed to accept an optional Firebase `auth` instance.
+The `$firebaseAuth` service now accepts an optional Firebase `auth` instance instead of a Firebase
+Database reference.
 
 ```js
 // Old
-$firebaseAuth(ref)
+$firebaseAuth(ref);
 
 // New
-$firebaseAuth()
+$firebaseAuth();
 // Or if you need to explicitly provide an auth instance
-$firebaseAuth(firebase.auth())
+$firebaseAuth(firebase.auth());
 ```
 
 Several authentication methods have been renamed and / or have different method signatures:
 
 | Old Method | New Method | Notes |
 |------------|------------|------------------|
 | `$authAnonymously(options)` | `$signInAnonymously()` | No longer takes any arguments |
-| `$authWithPassword(credentials)` | `$signInWithEmailAndPassword(email, password)` |   |
+| `$authWithPassword(credentials)` | `$signInWithEmailAndPassword(email, password)` | |
 | `$authWithCustomToken(token)` | `$signInWithCustomToken(token)` | |
 | `$authWithOAuthPopup(provider[, options])` | `$signInWithPopup(provider)` | `options` can be provided by passing a configured `firebase.database.AuthProvider` instead of a `provider` string |
 | `$authWithOAuthRedirect(provider[, options])` | `$signInWithRedirect(provider)` | `options` can be provided by passing a configured `firebase.database.AuthProvider` instead of a `provider` string |
@@ -52,7 +53,7 @@ Several authentication methods have been renamed and / or have different method
 | `$changePassword(credentials)` | `$updatePassword(newPassword)` | Changes the password of the currently signed in user |
 | `$resetPassword(credentials)` | `$sendPasswordResetEmail(email)` | |
 | `$unauth()` | `$signOut()` | |
-| `$onAuth(callback)` | `$onAuthStateChanged(callback)` |   |
+| `$onAuth(callback)` | `$onAuthStateChanged(callback)` | |
 
 
 ## Auth Payload Format Changes

src/FirebaseAuth.js

@@ -24,9 +24,12 @@
   FirebaseAuth = function($firebaseUtils, auth) {
     this._utils = $firebaseUtils;
 
-    if (typeof auth === 'string' || auth.ref) {
-      throw new Error('Please provide a Firebase auth instance (or nothing) instead of a URL or Database reference when creating a `$firebaseAuth` object.');
+    if (typeof auth === 'string') {
+      throw new Error('The $firebaseAuth service accepts a Firebase auth instance (or nothing) instead of a URL.');
+    } else if (typeof auth.ref !== 'undefined') {
+      throw new Error('The $firebaseAuth service accepts a Firebase auth instance (or nothing) instead of a Database reference.');
     }
+
     this._auth = auth;
     this._initialAuthResolver = this._initAuthResolver();
   };

tests/unit/FirebaseAuth.spec.js

@@ -110,12 +110,18 @@ describe('FirebaseAuth',function(){
   });
 
   it('will throw an error if a database instance is used in place of a Firebase auth instance',function(){
+    expect(function(){
+      $firebaseAuth(firebase.database());
+    }).toThrow();
+  });
+
+  it('will throw an error if a database reference is used in place of a Firebase auth instance',function(){
     expect(function(){
       $firebaseAuth(firebase.database().ref());
     }).toThrow();
   });
 
-  fit('will not throw an error if an auth instance is provided',function(){
+  it('will not throw an error if an auth instance is provided',function(){
       $firebaseAuth(firebase.auth());
   });