chore: Add tests for useInt64Timestamp behavior

Author: lqiu96

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

@@ -1731,7 +1731,10 @@ public TableDataList call() throws IOException {
           new PageImpl<>(
               new TableDataPageFetcher(tableId, schema, serviceOptions, cursor, pageOptionMap),
               cursor,
-              transformTableData(result.getRows(), schema, serviceOptions.getUseInt64Timestamps())),
+              transformTableData(
+                  result.getRows(),
+                  schema,
+                  serviceOptions.getDataFormatOptions().useInt64Timestamp())),
           result.getTotalRows());
     } catch (BigQueryRetryHelperException e) {
       throw BigQueryException.translateAndThrow(e);
@@ -2007,7 +2010,9 @@ public com.google.api.services.bigquery.model.QueryResponse call()
                   new QueryPageFetcher(jobId, schema, getOptions(), cursor, optionMap(options)),
                   cursor,
                   transformTableData(
-                      results.getRows(), schema, getOptions().getUseInt64Timestamps())))
+                      results.getRows(),
+                      schema,
+                      getOptions().getDataFormatOptions().useInt64Timestamp())))
           .setJobId(jobId)
           .setQueryId(results.getQueryId())
           .build();
@@ -2021,7 +2026,9 @@ public com.google.api.services.bigquery.model.QueryResponse call()
                 new TableDataPageFetcher(null, schema, getOptions(), null, optionMap(options)),
                 null,
                 transformTableData(
-                    results.getRows(), schema, getOptions().getUseInt64Timestamps())))
+                    results.getRows(),
+                    schema,
+                    getOptions().getDataFormatOptions().useInt64Timestamp())))
         // Return the JobID of the successful job
         .setJobId(
             results.getJobReference() != null ? JobId.fromPb(results.getJobReference()) : null)

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

@@ -43,7 +43,7 @@ public class BigQueryOptions extends ServiceOptions<BigQuery, BigQueryOptions> {
   // set the option ThrowNotFound when you want to throw the exception when the value not found
   private boolean setThrowNotFound;
   private boolean useInt64Timestamps;
-  private final DataFormatOptions dataFormatOptions;
+  private DataFormatOptions dataFormatOptions;
   private JobCreationMode defaultJobCreationMode = JobCreationMode.JOB_CREATION_MODE_UNSPECIFIED;
   private boolean enableOpenTelemetryTracing;
   private Tracer openTelemetryTracer;
@@ -235,9 +235,13 @@ public void setThrowNotFound(boolean setThrowNotFound) {
    *
    * <p>Alternative: {@code DataFormatOptions.newBuilder().setUseInt64Timestamp(...).build()}
    */
-  @ObsoleteApi("Use setDataFormatOptions(DataFormatOptions) instead")
+  @ObsoleteApi("Use Builder#setDataFormatOptions(DataFormatOptions) instead")
   public void setUseInt64Timestamps(boolean useInt64Timestamps) {
     this.useInt64Timestamps = useInt64Timestamps;
+    // Because this setter exists outside the Builder, DataFormatOptions needs be rebuilt to
+    // account for this setting.
+    this.dataFormatOptions =
+        dataFormatOptions.toBuilder().useInt64Timestamp(useInt64Timestamps).build();
   }
 
   @Deprecated
@@ -262,7 +266,7 @@ public boolean getThrowNotFound() {
    */
   @ObsoleteApi("Use getDataFormatOptions().isUseInt64Timestamp() instead")
   public boolean getUseInt64Timestamps() {
-    return useInt64Timestamps;
+    return dataFormatOptions.useInt64Timestamp();
   }
 
   public DataFormatOptions getDataFormatOptions() {

google-cloud-bigquery/src/test/java/com/google/cloud/bigquery/BigQueryOptionsTest.java

@@ -16,6 +16,11 @@
 
 package com.google.cloud.bigquery;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
 import com.google.cloud.TransportOptions;
 import org.junit.Assert;
 import org.junit.Test;
@@ -35,4 +40,52 @@ public void testInvalidTransport() {
       Assert.assertNotNull(expected.getMessage());
     }
   }
+
+  @Test
+  public void dataFormatOptions_createdByDefault() {
+    BigQueryOptions options = BigQueryOptions.newBuilder().build();
+
+    assertNotNull(options.getDataFormatOptions());
+    assertFalse(options.getDataFormatOptions().useInt64Timestamp());
+    assertEquals(
+        DataFormatOptions.TimestampFormatOptions.TIMESTAMP_OUTPUT_FORMAT_UNSPECIFIED,
+        options.getDataFormatOptions().timestampFormatOptions());
+  }
+
+  @Test
+  public void nonBuilderSetUseInt64Timestamp_capturedInDataFormatOptions() {
+    BigQueryOptions options =
+        BigQueryOptions.newBuilder()
+            .setDataFormatOptions(DataFormatOptions.newBuilder().useInt64Timestamp(false).build())
+            .build();
+    options.setUseInt64Timestamps(true);
+
+    assertTrue(options.getDataFormatOptions().useInt64Timestamp());
+  }
+
+  @Test
+  public void nonBuilderSetUseInt64Timestamp_overridesEverything() {
+    BigQueryOptions options = BigQueryOptions.newBuilder().build();
+    options.setUseInt64Timestamps(true);
+
+    assertTrue(options.getDataFormatOptions().useInt64Timestamp());
+  }
+
+  @Test
+  public void noDataFormatOptions_capturesUseInt64TimestampSetInBuilder() {
+    BigQueryOptions options = BigQueryOptions.newBuilder().setUseInt64Timestamps(true).build();
+
+    assertTrue(options.getDataFormatOptions().useInt64Timestamp());
+  }
+
+  @Test
+  public void dataFormatOptionsSetterHasPrecedence() {
+    BigQueryOptions options =
+        BigQueryOptions.newBuilder()
+            .setDataFormatOptions(DataFormatOptions.newBuilder().useInt64Timestamp(true).build())
+            .setUseInt64Timestamps(false)
+            .build();
+
+    assertTrue(options.getDataFormatOptions().useInt64Timestamp());
+  }
 }

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

@@ -71,6 +71,7 @@
 import com.google.cloud.bigquery.ConnectionSettings;
 import com.google.cloud.bigquery.CopyJobConfiguration;
 import com.google.cloud.bigquery.CsvOptions;
+import com.google.cloud.bigquery.DataFormatOptions;
 import com.google.cloud.bigquery.Dataset;
 import com.google.cloud.bigquery.DatasetId;
 import com.google.cloud.bigquery.DatasetInfo;
@@ -3462,8 +3463,11 @@ public void testLosslessTimestamp() throws InterruptedException {
     // Create new BQ object to toggle lossless timestamps without affecting
     // other tests.
     RemoteBigQueryHelper bigqueryHelper = RemoteBigQueryHelper.create();
-    BigQuery bigqueryLossless = bigqueryHelper.getOptions().getService();
-    bigqueryLossless.getOptions().setUseInt64Timestamps(true);
+    DataFormatOptions dataFormatOptions =
+        DataFormatOptions.newBuilder().useInt64Timestamp(true).build();
+    BigQueryOptions options =
+        bigqueryHelper.getOptions().toBuilder().setDataFormatOptions(dataFormatOptions).build();
+    BigQuery bigqueryLossless = options.getService();
 
     TableResult resultLossless =
         bigqueryLossless.query(