Fix test cases

Author: sakthivelmanii

google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionOptions.java

@@ -77,6 +77,7 @@
 import com.google.cloud.spanner.SpannerOptions;
 import com.google.cloud.spanner.connection.StatementExecutor.StatementExecutorType;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.MoreObjects;
 import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
 import com.google.common.base.Suppliers;
@@ -970,7 +971,7 @@ public TransportChannelProvider getChannelProvider() {
       return null;
     }
     try {
-      URL url = new URL(host);
+      URL url = new URL(MoreObjects.firstNonNull(host, DEFAULT_HOST));
       ExternalChannelProvider provider =
           ExternalChannelProvider.class.cast(Class.forName(channelProvider).newInstance());
       return provider.getChannelProvider(url.getHost(), url.getPort());

google-cloud-spanner/src/test/java/com/google/cloud/spanner/connection/ConnectionOptionsTest.java

@@ -60,7 +60,7 @@
 public class ConnectionOptionsTest {
   private static final String FILE_TEST_PATH =
       Objects.requireNonNull(ConnectionOptionsTest.class.getResource("test-key.json")).getFile();
-  private static final String DEFAULT_HOST = "https://spanner.googleapis.com";
+  private static final String DEFAULT_HOST = null;
   private static final String TEST_PROJECT = "test-project-123";
   private static final String TEST_INSTANCE = "test-instance-123";
   private static final String TEST_DATABASE = "test-database-123";