test(bigquery): add ITBigQueryTest integration tests for queryArrow (#14403)

This PR adds integration tests verifying the `queryArrow` client API
against the live BigQuery service.

It tests single-page and multi-page Arrow stream consumption, validating
row counts and VectorSchemaRoot iteration over live queries.

Author: jinseopkim0

java-bigquery/google-cloud-bigquery/src/main/java/com/google/cloud/bigquery/BigQueryImpl.java

@@ -24,8 +24,10 @@
 import com.google.api.core.BetaApi;
 import com.google.api.core.InternalApi;
 import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.core.NoCredentialsProvider;
 import com.google.api.gax.paging.Page;
 import com.google.api.gax.rpc.HeaderProvider;
+import com.google.api.gax.rpc.NoHeaderProvider;
 import com.google.api.services.bigquery.model.ErrorProto;
 import com.google.api.services.bigquery.model.GetQueryResultsResponse;
 import com.google.api.services.bigquery.model.ProjectList;
@@ -371,8 +373,10 @@ private static void configureReadSettings(
     if (options.getCredentials() != null) {
       settingsBuilder.setCredentialsProvider(
           FixedCredentialsProvider.create(options.getCredentials()));
+    } else {
+      settingsBuilder.setCredentialsProvider(NoCredentialsProvider.create());
     }
-    HeaderProvider headerProvider = options.getMergedHeaderProvider(null);
+    HeaderProvider headerProvider = options.getMergedHeaderProvider(new NoHeaderProvider());
     if (headerProvider != null) {
       settingsBuilder.setHeaderProvider(headerProvider);
     }

java-bigquery/google-cloud-bigquery/src/test/java/com/google/cloud/bigquery/it/ITBigQueryTest.java

@@ -45,6 +45,7 @@
 import com.google.cloud.bigquery.Acl.DatasetAclEntity;
 import com.google.cloud.bigquery.Acl.Expr;
 import com.google.cloud.bigquery.Acl.User;
+import com.google.cloud.bigquery.ArrowQueryResult;
 import com.google.cloud.bigquery.BigQuery;
 import com.google.cloud.bigquery.BigQuery.DatasetField;
 import com.google.cloud.bigquery.BigQuery.DatasetListOption;
@@ -118,6 +119,7 @@
 import com.google.cloud.bigquery.QueryJobConfiguration.JobCreationMode;
 import com.google.cloud.bigquery.QueryJobConfiguration.Priority;
 import com.google.cloud.bigquery.QueryParameterValue;
+import com.google.cloud.bigquery.QueryResultsFormat;
 import com.google.cloud.bigquery.Range;
 import com.google.cloud.bigquery.RangePartitioning;
 import com.google.cloud.bigquery.Routine;
@@ -203,6 +205,7 @@
 import java.util.concurrent.TimeoutException;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import org.apache.arrow.vector.VectorSchemaRoot;
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
@@ -7499,6 +7502,53 @@ void testQueryWithTimeout() throws InterruptedException {
     assertTrue(millis < 1_000_000 * 2);
   }
 
+  @Test
+  void testQueryResultsFormatArrow() throws InterruptedException {
+    String query = "SELECT 1 as id, 'hello' as name, TIMESTAMP('2026-08-10T12:00:00Z') as ts";
+    QueryJobConfiguration config =
+        QueryJobConfiguration.newBuilder(query)
+            .setQueryResultsFormat(QueryResultsFormat.ARROW)
+            .setJobCreationMode(JobCreationMode.JOB_CREATION_OPTIONAL)
+            .build();
+    try (ArrowQueryResult result = bigquery.queryArrow(config)) {
+      assertNotNull(result);
+      int batchCount = 0;
+      long totalRows = 0;
+      for (VectorSchemaRoot root : result) {
+        batchCount++;
+        totalRows += root.getRowCount();
+        assertEquals(1, root.getRowCount());
+      }
+      assertEquals(1, batchCount);
+      assertEquals(1, totalRows);
+    }
+  }
+
+  @Test
+  void testQueryResultsFormatArrowMultiPage() throws InterruptedException {
+    // Under fast-query execution, the initial REST response defaults to a 10 MB payload limit.
+    // Setting maxResults limits the initial page to 5,000 rows, forcing the remaining 10,000 rows
+    // to stream across multiple batches via the BigQuery Storage Read API.
+    String query = "SELECT x FROM UNNEST(GENERATE_ARRAY(1, 15000)) AS x";
+    QueryJobConfiguration config =
+        QueryJobConfiguration.newBuilder(query)
+            .setQueryResultsFormat(QueryResultsFormat.ARROW)
+            .setJobCreationMode(JobCreationMode.JOB_CREATION_OPTIONAL)
+            .setMaxResults(5000L)
+            .build();
+    try (ArrowQueryResult result = bigquery.queryArrow(config)) {
+      assertNotNull(result);
+      int batchCount = 0;
+      long totalRows = 0;
+      for (VectorSchemaRoot root : result) {
+        batchCount++;
+        totalRows += root.getRowCount();
+      }
+      assertTrue(batchCount > 1);
+      assertEquals(15000, totalRows);
+    }
+  }
+
   @Test
   void testUniverseDomainWithInvalidUniverseDomain() {
     RemoteBigQueryHelper bigqueryHelper = RemoteBigQueryHelper.create();