Add minimal tests for ClientSecrets

spec/fixtures/files/client_secrets.json

@@ -0,0 +1 @@
+{"installed":{"auth_uri":"https://accounts.google.com/o/oauth2/auth","client_secret":"i8YaXdGgiQ4_KrTVNGsB7QP1","token_uri":"https://accounts.google.com/o/oauth2/token","client_email":"","client_x509_cert_url":"","client_id":"898243283568.apps.googleusercontent.com","auth_provider_x509_cert_url":"https://www.googleapis.com/oauth2/v1/certs"}}

spec/google/api_client/client_secrets_spec.rb

@@ -0,0 +1,53 @@
+# encoding:utf-8
+
+# Copyright 2013 Google 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.
+
+require 'spec_helper'
+
+require 'google/api_client/client_secrets'
+
+FIXTURES_PATH = File.expand_path('../../../fixtures', __FILE__)
+
+RSpec.describe Google::APIClient::ClientSecrets do
+  
+  context 'with JSON file' do
+    let(:file) { File.join(FIXTURES_PATH, 'files', 'client_secrets.json') }
+    subject(:secrets) { Google::APIClient::ClientSecrets.load(file)}
+  
+    it 'should load the correct client ID' do
+      expect(secrets.client_id).to be == '898243283568.apps.googleusercontent.com'
+    end
+
+    it 'should load the correct client secret' do
+      expect(secrets.client_secret).to be == 'i8YaXdGgiQ4_KrTVNGsB7QP1'
+    end
+    
+    context 'serialzed to hash' do
+      subject(:hash) { secrets.to_hash }
+      it 'should contain the flow as the first key' do
+        expect(hash).to have_key "installed"
+      end
+
+      it 'should contain the client ID' do
+        expect(hash["installed"]["client_id"]).to be == '898243283568.apps.googleusercontent.com'
+      end
+
+      it 'should contain the client secret' do
+        expect(hash["installed"]["client_secret"]).to be == 'i8YaXdGgiQ4_KrTVNGsB7QP1'
+      end
+
+    end
+  end
+end