read write IT using txn options

Author: shobhitsg

google-cloud-spanner/src/test/java/com/google/cloud/spanner/it/ITTransactionTest.java

@@ -52,6 +52,8 @@
 import com.google.common.collect.Sets;
 import com.google.common.util.concurrent.SettableFuture;
 import com.google.common.util.concurrent.Uninterruptibles;
+import com.google.spanner.v1.TransactionOptions.IsolationLevel;
+import com.google.spanner.v1.TransactionOptions.ReadWrite.ReadLockMode;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -213,6 +215,19 @@ public void basicsUsingQuery() throws InterruptedException {
         });
   }
 
+  @Test
+  public void isolationLevelAndReadLockModeTest() {
+    TransactionCallable<Long> callable =
+        transaction ->
+            transaction.executeUpdate(Statement.of("INSERT INTO T (K, V) VALUES ('test1', 2)"));
+    TransactionRunner runner =
+        client.readWriteTransaction(
+            Options.isolationLevel(IsolationLevel.REPEATABLE_READ),
+            Options.readLockMode(ReadLockMode.OPTIMISTIC));
+    Long updatedRows = runner.run(callable);
+    assertThat(updatedRows).isEqualTo(1L);
+  }
+
   @Test
   public void userExceptionPreventsCommit() {
     class UserException extends Exception {