fix: local connection checker ignores exceptions

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

@@ -19,13 +19,11 @@
 import com.google.api.gax.core.NoCredentialsProvider;
 import com.google.api.gax.grpc.InstantiatingGrpcChannelProvider;
 import com.google.api.gax.rpc.UnavailableException;
-import com.google.api.gax.rpc.UnimplementedException;
 import com.google.cloud.spanner.ErrorCode;
 import com.google.cloud.spanner.SpannerExceptionFactory;
 import com.google.cloud.spanner.admin.instance.v1.stub.GrpcInstanceAdminStub;
 import com.google.cloud.spanner.admin.instance.v1.stub.InstanceAdminStubSettings;
 import com.google.spanner.admin.instance.v1.ListInstanceConfigsRequest;
-import java.io.IOException;
 import org.threeten.bp.Duration;
 
 /**
@@ -95,10 +93,9 @@ void checkLocalConnection(ConnectionOptions options) {
                   emulatorHost);
         }
         throw SpannerExceptionFactory.newSpannerException(ErrorCode.UNAVAILABLE, msg);
-      } catch (UnimplementedException e) {
-        // Ignore, this is probably a local mock server.
-      } catch (IOException e) {
-        // Ignore, this method is not checking whether valid credentials have been set.
+      } catch (Throwable t) {
+        // Ignore, any other exceptions should also be thrown when connecting to the remote
+        // server and should not be treated here.
       }
     }
   }

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

@@ -17,39 +17,50 @@
 
 import static com.google.cloud.spanner.MockSpannerTestUtil.SELECT1;
 import static com.google.cloud.spanner.MockSpannerTestUtil.SELECT1_RESULTSET;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
 
 import com.google.cloud.spanner.MockSpannerServiceImpl;
 import com.google.cloud.spanner.ResultSet;
+import com.google.cloud.spanner.SpannerException;
 import io.grpc.Server;
 import io.grpc.netty.shaded.io.grpc.netty.NettyServerBuilder;
 import java.net.InetSocketAddress;
-import org.junit.After;
+import org.junit.AfterClass;
 import org.junit.Before;
+import org.junit.BeforeClass;
 import org.junit.Test;
 
 public class LocalConnectionCheckerTest {
 
-  private MockSpannerServiceImpl mockSpanner;
-  private Server server;
-  private InetSocketAddress address;
+  private static MockSpannerServiceImpl mockSpanner;
+  private static Server server;
+  private LocalConnectionChecker connectionChecker;
 
-  @Before
-  public void setUp() throws Exception {
+  @BeforeClass
+  public static void beforeClass() throws Exception {
     mockSpanner = new MockSpannerServiceImpl();
     mockSpanner.setAbortProbability(0.0D); // We don't want any unpredictable aborted transactions.
-    address = new InetSocketAddress("localhost", 0);
+
+    final InetSocketAddress address = new InetSocketAddress("localhost", 0);
     server = NettyServerBuilder.forAddress(address).addService(mockSpanner).build();
     server.start();
   }
 
-  @After
-  public void tearDown() throws Exception {
+  @AfterClass
+  public static void afterClass() throws Exception {
     server.shutdown();
     server.awaitTermination();
   }
 
+  @Before
+  public void setUp() {
+    mockSpanner.reset();
+    connectionChecker = new LocalConnectionChecker();
+  }
+
   @Test
-  public void localConnectionCheckerWorksWithMockSpanner() {
+  public void testMockSpanner() {
     final String uri =
         String.format(
             "cloudspanner://localhost:%d/projects/proj/instances/inst/databases/db?usePlainText=true",
@@ -63,4 +74,28 @@ public void localConnectionCheckerWorksWithMockSpanner() {
       while (resultSet.next()) {}
     }
   }
+
+  @Test
+  public void testNoRunningEmulator() {
+    final int port = server.getPort() - 1;
+    final String uri =
+        String.format(
+            "cloudspanner://localhost:%d/projects/proj/instances/inst/databases/db?usePlainText=true",
+            port);
+    final ConnectionOptions connectionOptions = ConnectionOptions.newBuilder().setUri(uri).build();
+
+    try {
+      connectionChecker.checkLocalConnection(connectionOptions);
+      fail("Unavailable exception expected");
+    } catch (SpannerException e) {
+      assertEquals(
+          "UNAVAILABLE: The connection string '"
+              + uri
+              + "' contains host 'localhost:"
+              + port
+              + "', but no running emulator or other server could be found at that address.\n"
+              + "Please check the connection string and/or that the emulator is running.",
+          e.getMessage());
+    }
+  }
 }