docs(samples): added copy table and accompanying test (#414)

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

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+/*
+ * 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_copy_table]
+import com.google.cloud.bigquery.BigQuery;
+import com.google.cloud.bigquery.BigQueryException;
+import com.google.cloud.bigquery.BigQueryOptions;
+import com.google.cloud.bigquery.CopyJobConfiguration;
+import com.google.cloud.bigquery.Job;
+import com.google.cloud.bigquery.JobInfo;
+import com.google.cloud.bigquery.TableId;
+
+public class CopyTable {
+
+  public static void runCopyTable() {
+    // TODO(developer): Replace these variables before running the sample.
+    String destinationDatasetName = "MY_DESTINATION_DATASET_NAME";
+    String destinationTableId = "MY_DESTINATION_TABLE_NAME";
+    String sourceDatasetName = "MY_SOURCE_DATASET_NAME";
+    String sourceTableId = "MY_SOURCE_TABLE_NAME";
+
+    copyTable(sourceDatasetName, sourceTableId, destinationDatasetName, destinationTableId);
+  }
+
+  public static void copyTable(String sourceDatasetName, String sourceTableId,
+      String destinationDatasetName, String destinationTableId) {
+    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();
+
+      TableId sourceTable = TableId.of(sourceDatasetName, sourceTableId);
+      TableId destinationTable = TableId.of(destinationDatasetName, destinationTableId);
+
+      // For more information on CopyJobConfiguration see:
+      // https://googleapis.dev/java/google-cloud-clients/latest/com/google/cloud/bigquery/JobConfiguration.html
+      CopyJobConfiguration configuration =
+          CopyJobConfiguration.newBuilder(
+                destinationTable,
+                sourceTable
+              ).build();
+
+      // For more information on Job see:
+      // https://googleapis.dev/java/google-cloud-clients/latest/index.html?com/google/cloud/bigquery/package-summary.html
+      Job job = bigquery.create(JobInfo.of(configuration));
+
+      // Blocks until this job completes its execution, either failing or succeeding.
+      Job completedJob = job.waitFor();
+      if (completedJob == null) {
+        System.out.println("Job not executed since it no longer exists.");
+        return;
+      } else if (completedJob.getStatus().getError() != null) {
+        System.out.println(
+            "BigQuery was unable to copy table due to an error: \n" + job.getStatus().getError());
+        return;
+      }
+      System.out.println("Table copied successfully.");
+    } catch (BigQueryException | InterruptedException e) {
+      System.out.println("Table copying job was interrupted. \n" + e.toString());
+    }
+  }
+}
+// [END bigquery_copy_table]

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

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+/*
+ * 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 com.google.cloud.bigquery.Field;
+import com.google.cloud.bigquery.Schema;
+import com.google.cloud.bigquery.StandardSQLTypeName;
+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 CopyTableIT {
+  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() throws Exception {
+    bout = new ByteArrayOutputStream();
+    out = new PrintStream(bout);
+    System.setOut(out);
+  }
+
+  @After
+  public void tearDown() {
+    System.setOut(null);
+  }
+
+  @Test
+  public void testCopyTable() {
+    // Create a new destination and source table for each test since existing table cannot be overwritten
+    String generatedDestTableName = "gcloud_test_table_temp_" +
+        UUID.randomUUID().toString().replace('-', '_');
+    String generatedSourceTableName = "gcloud_test_table_temp_" +
+        UUID.randomUUID().toString().replace('-', '_');
+
+    //Adding an arbitrary table schema so we aren't copying nothing.
+    Schema schema =
+        Schema.of(
+            Field.of("stringField", StandardSQLTypeName.STRING),
+            Field.of("booleanField", StandardSQLTypeName.BOOL));
+
+    CreateTable.createTable(BIGQUERY_DATASET_NAME, generatedDestTableName, schema);
+    CreateTable.createTable(BIGQUERY_DATASET_NAME, generatedSourceTableName, schema);
+
+    CopyTable.copyTable(BIGQUERY_DATASET_NAME, generatedSourceTableName,
+        BIGQUERY_DATASET_NAME, generatedDestTableName);
+    assertThat(bout.toString()).contains("Table copied successfully.");
+
+    // Clean up
+    DeleteTable.deleteTable(BIGQUERY_DATASET_NAME, generatedDestTableName);
+    DeleteTable.deleteTable(BIGQUERY_DATASET_NAME, generatedSourceTableName);
+  }
+}