docs(spanner): migrate quickstart sample

Migrates quickstart.js from googleapis/nodejs-spanner and enables its test suite in spanner.test.js.

Author: sakthivelmanii

spanner/quickstart.js

@@ -0,0 +1,63 @@
+// Copyright 2016 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';
+
+// [START spanner_quickstart]
+const {Spanner} = require('@google-cloud/spanner');
+const {status} = require('@grpc/grpc-js');
+
+// Creates a client using the ambient project ID or environment configuration
+const spanner = new Spanner();
+
+/**
+ * Executes a query against a Cloud Spanner database.
+ *
+ * @param {string} projectId The project ID containing the Spanner instance (for example, 'example-project-id').
+ * @param {string} instanceId The ID of the Spanner instance (for example, 'example-instance').
+ * @param {string} databaseId The ID of the Spanner database (for example 'example-database').
+ */
+async function quickstart(projectId, instanceId, databaseId) {
+  try {
+    // Gets a reference to a Cloud Spanner instance and database
+    const instance = spanner.instance(instanceId);
+    const database = instance.database(databaseId);
+
+    const query = {
+      sql: 'SELECT 1',
+    };
+
+    const [rows] = await database.run(query);
+
+    console.log(`Query successfully executed. ${rows.length} row(s) found.`);
+    rows.forEach(row => {
+      console.log(`  Row details: ${JSON.stringify(row)}`);
+    });
+  } catch (err) {
+    if (err.code === status.NOT_FOUND) {
+      console.error(
+        `Resource not found. Please verify that instance '${instanceId}' and database '${databaseId}' exist under project '${projectId}'.`
+      );
+    } else {
+      console.error('An unexpected error occurred during execution:', err);
+    }
+  }
+}
+// [END spanner_quickstart]
+
+if (require.main === module) {
+  quickstart(...process.argv.slice(2));
+}
+
+module.exports = {quickstart};

spanner/system-test/spanner.test.js

@@ -585,14 +585,17 @@ describe('Autogenerated Admin Clients', () => {
     });
   });
 
-  describe.skip('quickstart', () => {
+  describe('quickstart', () => {
     // Running the quickstart test in here since there's already a spanner
     // instance and database set up at this point.
     it('should query a table', async () => {
       const output = execSync(
         `node quickstart ${PROJECT_ID} ${INSTANCE_ID} ${DATABASE_ID}`
       );
-      assert.match(output, /Query: \d+ found./);
+      assert.match(
+        output,
+        /Query successfully executed\. \d+ row\(s\) found\./
+      );
     });
   });