feat(storage): introduce storage client endpoint sample and test for migration (#4263)

Co-authored-by: Jennifer Davis <sigje@google.com>

Author: angelcaamal

storage/setClientEndpoint.js

@@ -0,0 +1,53 @@
+// Copyright 2022 Google LLC
+//
+// 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.
+
+'use strict';
+
+/**
+ * This application demonstrates set a custom endpoint with
+ * the Google Cloud Storage API.
+ *
+ * For more information, see the README.md under /storage and the documentation
+ * at https://cloud.google.com/storage/docs.
+ */
+
+function main(apiEndpoint = 'https://storage.googleapis.com') {
+  // [START storage_set_client_endpoint]
+  /**
+   * TODO(developer): Uncomment the following lines before running the sample.
+   */
+  // The custom endpoint to which requests should be made
+  // const apiEndpoint = 'https://yourcustomendpoint.com';
+
+  // Imports the Google Cloud client library
+  const {Storage} = require('@google-cloud/storage');
+  try {
+    // Creates a client
+    const storage = new Storage({
+      apiEndpoint: apiEndpoint,
+      useAuthWithCustomEndpoint: true,
+    });
+
+    console.log(`Client initiated with endpoint: ${storage.apiEndpoint}.`);
+  } catch (error) {
+    console.error(
+      'Error executing set client endpoint:',
+      error.message || error
+    );
+  }
+
+  // [END storage_set_client_endpoint]
+}
+
+main(...process.argv.slice(2));

storage/system-test/storage.test.js

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+// Copyright 2022 Google LLC
+//
+// 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.
+
+'use strict';
+
+const {assert} = require('chai');
+const {it} = require('mocha');
+const cp = require('child_process');
+
+const execSync = cmd => cp.execSync(cmd, {encoding: 'utf-8'});
+
+it('should intialize storage with a custom api endpoint', async () => {
+  const apiEndpoint = 'https://storage.googleapis.com';
+  const output = execSync(`node setClientEndpoint.js ${apiEndpoint}`);
+  assert.match(
+    output,
+    new RegExp(`Client initiated with endpoint: ${apiEndpoint}.`)
+  );
+});