Add better comments and tests

Author: levimatheri

FirebaseAdmin/FirebaseAdmin.Tests/Auth/FirebaseUserManagerTest.cs

@@ -86,15 +86,16 @@ public async Task GetUserById()
                     ProjectId = MockProjectId,
                     ClientFactory = factory,
                 });
-            await userManager.GetUserById("user1");
+            UserRecord userRecord = await userManager.GetUserById("user1");
+            Assert.Equal("user1", userRecord.Uid);
         }
 
         [Fact]
-        public async Task GetUserByIdIncorrectUid()
+        public async Task GetUserByIdUserNotFound()
         {
             var handler = new MockMessageHandler()
             {
-                Response = new UserRecord("testuser"),
+                StatusCode = HttpStatusCode.NotFound,
             };
             var factory = new MockHttpClientFactory(handler);
             var userManager = new FirebaseUserManager(
@@ -109,7 +110,7 @@ await Assert.ThrowsAsync<FirebaseException>(
         }
 
         [Fact]
-        public async Task GetUserByIdHttpError()
+        public async Task GetUserByIdInvalidToken()
         {
             var handler = new MockMessageHandler()
             {
@@ -244,7 +245,26 @@ public async Task DeleteUser()
         }
 
         [Fact]
-        public async Task DeleteUserHttpError()
+        public async Task DeleteUserNotFound()
+        {
+            var handler = new MockMessageHandler()
+            {
+                StatusCode = HttpStatusCode.NotFound,
+            };
+            var factory = new MockHttpClientFactory(handler);
+            var userManager = new FirebaseUserManager(
+                new FirebaseUserManagerArgs
+                {
+                    Credential = MockCredential,
+                    ProjectId = MockProjectId,
+                    ClientFactory = factory,
+                });
+            await Assert.ThrowsAsync<FirebaseException>(
+               async () => await userManager.DeleteUser("user1"));
+        }
+
+        [Fact]
+        public async Task DeleteUserInvalidToken()
         {
             var handler = new MockMessageHandler()
             {

FirebaseAdmin/FirebaseAdmin/Auth/FirebaseUserManager.cs

@@ -62,14 +62,19 @@ public static FirebaseUserManager Create(FirebaseApp app)
         }
 
         /// <summary>
-        /// Get a user by id.
+        /// Gets the user data corresponding to the given user ID.
         /// </summary>
-        /// <param name="uid">The query user id.</param>
+        /// <param name="uid">A user ID string.</param>
         /// <param name="cancellationToken">For asynchronous operation.</param>
         /// <returns>A record of user with the queried id if one exists.</returns>
         public async Task<UserRecord> GetUserById(
             string uid, CancellationToken cancellationToken = default(CancellationToken))
         {
+            if (string.IsNullOrEmpty(uid))
+            {
+                throw new ArgumentException("Failed to get user. User id cannot be null or empty");
+            }
+
             const string getUserPath = "accounts:lookup";
             var payload = new Dictionary<string, object>()
             {
@@ -112,6 +117,11 @@ public async Task UpdateUserAsync(
         public async Task DeleteUser(
             string uid, CancellationToken cancellationToken = default(CancellationToken))
         {
+            if (string.IsNullOrEmpty(uid))
+            {
+                throw new ArgumentException("Failed to delete user. User id cannot be null or empty");
+            }
+
             const string getUserPath = "accounts:delete";
             var payload = new Dictionary<string, object>()
             {