docs(samples): adding destination query sample and test (#418)

@stephaniewang526

samples/snippets/src/main/java/com/example/bigquery/SaveQueryToTable.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2020 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.
+ */
+
+package com.example.bigquery;
+
+// [START bigquery_query_destination_table]
+import com.google.cloud.bigquery.BigQuery;
+import com.google.cloud.bigquery.BigQueryException;
+import com.google.cloud.bigquery.BigQueryOptions;
+import com.google.cloud.bigquery.QueryJobConfiguration;
+import com.google.cloud.bigquery.TableId;
+
+public class SaveQueryToTable {
+
+  public static void runSaveQueryToTable() {
+    // TODO(developer): Replace these variables before running the sample.
+    String query =
+        "SELECT corpus FROM `bigquery-public-data.samples.shakespeare` GROUP BY corpus;";
+    String destinationTable = "MY_TABLE";
+    String destinationDataset = "MY_DATASET";
+
+    saveQueryToTable(destinationDataset, destinationTable, query);
+  }
+
+  public static void saveQueryToTable(String destinationDataset,
+      String destinationTableId, String query) {
+    try {
+      // Initialize client that will be used to send requests. This client only needs to be created
+      // once, and can be reused for multiple requests.
+      BigQuery bigquery = BigQueryOptions.getDefaultInstance().getService();
+
+      // Identify the destination table
+      TableId destinationTable = TableId.of(destinationDataset, destinationTableId);
+
+      // Build the query job
+      QueryJobConfiguration queryConfig =
+          QueryJobConfiguration.newBuilder(query).setDestinationTable(destinationTable).build();
+
+      // Execute the query.
+      bigquery.query(queryConfig);
+
+      // The results are now saved in the destination table.
+
+      System.out.println("Saved query ran successfully");
+    } catch (BigQueryException | InterruptedException e) {
+      System.out.println("Saved query did not run \n" + e.toString());
+    }
+  }
+}
+// [END bigquery_query_destination_table]

samples/snippets/src/test/java/com/example/bigquery/SaveQueryToTableIT.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2020 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.
+ */
+
+package com.example.bigquery;
+
+import static com.google.common.truth.Truth.assertThat;
+import static junit.framework.TestCase.assertNotNull;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.util.UUID;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class SaveQueryToTableIT {
+  private ByteArrayOutputStream bout;
+  private PrintStream out;
+
+
+  private static final String BIGQUERY_DATASET_NAME = System.getenv("BIGQUERY_DATASET_NAME");
+
+  private static void requireEnvVar(String varName) {
+    assertNotNull(
+        "Environment variable " + varName + " is required to perform these tests.",
+        System.getenv(varName));
+  }
+
+  @BeforeClass
+  public static void checkRequirements() {
+    requireEnvVar("BIGQUERY_DATASET_NAME");
+  }
+
+  @Before
+  public void setUp() {
+    bout = new ByteArrayOutputStream();
+    out = new PrintStream(bout);
+    System.setOut(out);
+  }
+
+  @After
+  public void tearDown() {
+    System.setOut(null);
+  }
+
+  @Test
+  public void testSaveQueryToTable() {
+    String tableName = "MY_TABLE_NAME_" + UUID.randomUUID().toString().replace("-", "_");
+    String query =
+        "SELECT corpus FROM `bigquery-public-data.samples.shakespeare` GROUP BY corpus;";
+
+    SaveQueryToTable.saveQueryToTable(BIGQUERY_DATASET_NAME, tableName, query);
+
+    assertThat(bout.toString()).contains("Saved query ran successfully");
+
+    // Clean up
+    DeleteTable.deleteTable(BIGQUERY_DATASET_NAME, tableName);
+  }
+}