test(spanner): unflake ITBulkConnectionTest.testBulkCreateConnectionsMultiThreaded

Author: sakthivelmanii

java-spanner/google-cloud-spanner/src/test/java/com/google/cloud/spanner/connection/it/ITBulkConnectionTest.java

@@ -19,6 +19,8 @@
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.CoreMatchers.notNullValue;
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
 
 import com.google.cloud.spanner.ResultSet;
 import com.google.cloud.spanner.SerialIntegrationTest;
@@ -28,6 +30,7 @@
 import java.util.List;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
@@ -65,22 +68,27 @@ public void testBulkCreateConnectionsSingleThreaded() {
   }
 
   @Test
-  public void testBulkCreateConnectionsMultiThreaded() throws InterruptedException {
+  public void testBulkCreateConnectionsMultiThreaded() throws Exception {
     ExecutorService executor = Executors.newFixedThreadPool(50);
+    List<Future<?>> futures = new ArrayList<>(NUMBER_OF_TEST_CONNECTIONS);
     for (int i = 0; i < NUMBER_OF_TEST_CONNECTIONS; i++) {
-      executor.submit(
-          () -> {
-            try (ITConnection connection = createConnection()) {
-              try (ResultSet rs = connection.executeQuery(Statement.of("select 1"))) {
-                assertThat(rs.next(), is(true));
-                assertThat(connection.getReadTimestamp(), is(notNullValue()));
-              }
-            }
-            return null;
-          });
+      futures.add(
+          executor.submit(
+              () -> {
+                try (ITConnection connection = createConnection()) {
+                  try (ResultSet rs = connection.executeQuery(Statement.of("select 1"))) {
+                    assertThat(rs.next(), is(true));
+                    assertThat(connection.getReadTimestamp(), is(notNullValue()));
+                  }
+                }
+                return null;
+              }));
     }
     executor.shutdown();
-    executor.awaitTermination(10L, TimeUnit.SECONDS);
+    assertTrue(executor.awaitTermination(60L, TimeUnit.SECONDS));
+    for (Future<?> future : futures) {
+      assertNull(future.get());
+    }
     // close Spanner instances explicitly. This method will throw an exception if there are any
     // connections still open in the pool
     closeSpanner();