Move LoginHandler into LoginServer which others embed (#3431)

* Move LoginHandler into LoginServer which others embed

* Add unit tests for loginServer

cmd/login-server_test.go

@@ -0,0 +1,67 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import "testing"
+
+func TestLoginHandler(t *testing.T) {
+	rootPath, err := newTestConfig("us-east-1")
+	if err != nil {
+		t.Fatalf("Failed to create test config - %v", err)
+	}
+	defer removeAll(rootPath)
+	creds := serverConfig.GetCredential()
+	ls := loginServer{}
+	testCases := []struct {
+		args        RPCLoginArgs
+		expectedErr error
+	}{
+		// Valid username and password
+		{
+			args:        RPCLoginArgs{Username: creds.AccessKeyID, Password: creds.SecretAccessKey},
+			expectedErr: nil,
+		},
+		// Invalid username length
+		{
+			args:        RPCLoginArgs{Username: "aaa", Password: "minio123"},
+			expectedErr: errInvalidAccessKeyLength,
+		},
+		// Invalid password length
+		{
+			args:        RPCLoginArgs{Username: "minio", Password: "aaa"},
+			expectedErr: errInvalidSecretKeyLength,
+		},
+		// Invalid username
+		{
+			args:        RPCLoginArgs{Username: "aaaaa", Password: creds.SecretAccessKey},
+			expectedErr: errInvalidAccessKeyID,
+		},
+		// Invalid password
+		{
+			args:        RPCLoginArgs{Username: creds.AccessKeyID, Password: "aaaaaaaa"},
+			expectedErr: errAuthentication,
+		},
+	}
+	for i, test := range testCases {
+		reply := RPCLoginReply{}
+		err := ls.LoginHandler(&test.args, &reply)
+		if err != test.expectedErr {
+			t.Errorf("Test %d: Expected error %v but received %v",
+				i+1, test.expectedErr, err)
+		}
+	}
+}