samples (test): fixed the flaky test (GoogleCloudPlatform#3611)

* samples (test): fixed the flaky test

* removed unused var

* added missing exception

Author: munkhuushmgl

vision/cloud-client/src/main/java/com/example/vision/snippets/DetectLandmarksUrl.java

@@ -25,6 +25,8 @@
 import com.google.cloud.vision.v1.ImageAnnotatorClient;
 import com.google.cloud.vision.v1.ImageSource;
 import com.google.cloud.vision.v1.LocationInfo;
+import io.grpc.Status;
+import io.grpc.StatusRuntimeException;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
@@ -38,7 +40,7 @@ public static void detectLandmarksUrl() throws IOException {
   }
 
   // Detects landmarks in the specified URI.
-  public static void detectLandmarksUrl(String uri) throws IOException {
+  public static void detectLandmarksUrl(String uri) throws IOException, StatusRuntimeException {
     List<AnnotateImageRequest> requests = new ArrayList<>();
 
     ImageSource imgSource = ImageSource.newBuilder().setImageUri(uri).build();
@@ -58,7 +60,7 @@ public static void detectLandmarksUrl(String uri) throws IOException {
       for (AnnotateImageResponse res : responses) {
         if (res.hasError()) {
           System.out.format("Error: %s%n", res.getError().getMessage());
-          return;
+          throw new StatusRuntimeException(Status.UNAVAILABLE);
         }
 
         // For full list of available annotations, see http://g.co/cloud/vision/docs

vision/cloud-client/src/test/java/com/example/vision/DetectLandmarksGcsTest.java

@@ -20,6 +20,7 @@
 
 import com.example.vision.snippets.DetectLandmarksGcs;
 import com.example.vision.snippets.DetectLandmarksUrl;
+import io.grpc.StatusRuntimeException;
 import java.io.ByteArrayOutputStream;
 import java.io.PrintStream;
 import org.junit.After;
@@ -63,11 +64,21 @@ public void testLandmarksUrl() throws Exception {
 
   @Test
   public void testLandmarksGcs() throws Exception {
-    // Act
-    DetectLandmarksGcs.detectLandmarksGcs("gs://" + ASSET_BUCKET + "/vision/landmark/pofa.jpg");
+    int tryCount = 0;
+    int maxTries = 3;
 
-    // Assert
-    String got = bout.toString().toLowerCase();
-    assertThat(got).contains("palace of fine arts");
+    while (tryCount < maxTries) {
+      try {
+        // Act
+        DetectLandmarksGcs.detectLandmarksGcs("gs://" + ASSET_BUCKET + "/vision/landmark/pofa.jpg");
+        // Assert
+        String got = bout.toString().toLowerCase();
+        assertThat(got).contains("palace of fine arts");
+        break;
+      } catch (StatusRuntimeException ex) {
+        System.out.println("Retrying...");
+        tryCount++;
+      }
+    }
   }
 }