samples: Translate flaky tests (#297)

Fixes #292 #268 #267   ☕️

This is the draft
I do not know it is considered as good test design using base class 

I basically got the idea from the stack overflow answer: 

https://stackoverflow.com/questions/8295100/how-to-re-run-failed-junit-tests-immediately

Author: munkhuushmgl

translate/snippets/src/main/java/com/example/translate/BatchTranslateText.java

@@ -29,6 +29,7 @@
 import com.google.cloud.translate.v3.TranslationServiceClient;
 import java.io.IOException;
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 
@@ -85,7 +86,11 @@ public static void batchTranslateText(
           client.batchTranslateTextAsync(request);
 
       System.out.println("Waiting for operation to complete...");
-      BatchTranslateResponse response = future.get(450, TimeUnit.SECONDS);
+
+      // random number between 300 - 450 (maximum allowed seconds)
+      long randomNumber = ThreadLocalRandom.current().nextInt(300, 450);
+      BatchTranslateResponse response = future.get(randomNumber, TimeUnit.SECONDS);
+
       System.out.printf("Total Characters: %s\n", response.getTotalCharacters());
       System.out.printf("Translated Characters: %s\n", response.getTranslatedCharacters());
     }

translate/snippets/src/main/java/com/example/translate/BatchTranslateTextWithGlossary.java

@@ -31,6 +31,7 @@
 import com.google.cloud.translate.v3.TranslationServiceClient;
 import java.io.IOException;
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 
@@ -103,7 +104,11 @@ public static void batchTranslateTextWithGlossary(
           client.batchTranslateTextAsync(request);
 
       System.out.println("Waiting for operation to complete...");
-      BatchTranslateResponse response = future.get(450, TimeUnit.SECONDS);
+      
+      // random number between 300 - 450 (maximum allowed seconds)
+      long randomNumber = ThreadLocalRandom.current().nextInt(300, 450);
+      BatchTranslateResponse response = future.get(randomNumber, TimeUnit.SECONDS);
+      
       // Display the translation for each input text provided
       System.out.printf("Total Characters: %s\n", response.getTotalCharacters());
       System.out.printf("Translated Characters: %s\n", response.getTranslatedCharacters());

translate/snippets/src/main/java/com/example/translate/BatchTranslateTextWithGlossaryAndModel.java

@@ -31,6 +31,7 @@
 import com.google.cloud.translate.v3.TranslationServiceClient;
 import java.io.IOException;
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 
@@ -110,7 +111,11 @@ public static void batchTranslateTextWithGlossaryAndModel(
           client.batchTranslateTextAsync(request);
 
       System.out.println("Waiting for operation to complete...");
-      BatchTranslateResponse response = future.get(450, TimeUnit.SECONDS);
+
+      // random number between 300 - 450 (maximum allowed seconds)
+      long randomNumber = ThreadLocalRandom.current().nextInt(300, 450);
+      BatchTranslateResponse response = future.get(randomNumber, TimeUnit.SECONDS);
+      
       // Display the translation for each input text provided
       System.out.printf("Total Characters: %s\n", response.getTotalCharacters());
       System.out.printf("Translated Characters: %s\n", response.getTranslatedCharacters());

translate/snippets/src/main/java/com/example/translate/BatchTranslateTextWithModel.java

@@ -29,6 +29,7 @@
 import com.google.cloud.translate.v3.TranslationServiceClient;
 import java.io.IOException;
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 
@@ -100,7 +101,11 @@ public static void batchTranslateTextWithModel(
           client.batchTranslateTextAsync(request);
 
       System.out.println("Waiting for operation to complete...");
-      BatchTranslateResponse response = future.get(450, TimeUnit.SECONDS);
+
+      // random number between 300 - 450 (maximum allowed seconds)
+      long randomNumber = ThreadLocalRandom.current().nextInt(300, 450);
+      BatchTranslateResponse response = future.get(randomNumber, TimeUnit.SECONDS);
+
       // Display the translation for each input text provided
       System.out.printf("Total Characters: %s\n", response.getTotalCharacters());
       System.out.printf("Translated Characters: %s\n", response.getTranslatedCharacters());

translate/snippets/src/test/java/com/example/translate/BatchTranslateTextTests.java

@@ -32,6 +32,7 @@
 import org.junit.After;
 import org.junit.Before;
 import org.junit.BeforeClass;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -48,6 +49,7 @@ public class BatchTranslateTextTests {
 
   private ByteArrayOutputStream bout;
   private PrintStream out;
+  @Rule public Retry retry = new Retry(3);
 
   private static void cleanUpBucket() {
     Storage storage = StorageOptions.getDefaultInstance().getService();
@@ -87,23 +89,28 @@ public static void checkRequirements() {
     requireEnvVar("GOOGLE_CLOUD_PROJECT");
   }
 
+  private PrintStream originalPrintStream;
+
   @Before
   public void setUp() {
     bout = new ByteArrayOutputStream();
     out = new PrintStream(bout);
+    originalPrintStream = System.out;
     System.setOut(out);
   }
 
   @After
   public void tearDown() {
     cleanUpBucket();
-    System.setOut(null);
+    System.out.flush();
+    System.setOut(originalPrintStream);
   }
 
   @Test
   public void testBatchTranslateText()
       throws InterruptedException, ExecutionException, IOException, TimeoutException {
     BatchTranslateText.batchTranslateText(PROJECT_ID, "en", "es", INPUT_URI, OUTPUT_URI);
+
     String got = bout.toString();
     assertThat(got).contains("Total Characters: 13");
   }

translate/snippets/src/test/java/com/example/translate/BatchTranslateTextWithGlossaryAndModelTests.java

@@ -34,6 +34,7 @@
 import org.junit.After;
 import org.junit.Before;
 import org.junit.BeforeClass;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -56,6 +57,7 @@ public class BatchTranslateTextWithGlossaryAndModelTests {
 
   private ByteArrayOutputStream bout;
   private PrintStream out;
+  @Rule public Retry retry = new Retry(3);
 
   private static final void cleanUpBucket() {
     Storage storage = StorageOptions.getDefaultInstance().getService();
@@ -95,6 +97,8 @@ public static void checkRequirements() {
     requireEnvVar("GOOGLE_CLOUD_PROJECT");
   }
 
+  private PrintStream originalPrintStream;
+
   @Before
   public void setUp() throws InterruptedException, ExecutionException, IOException {
     // Create a glossary that can be used in the test
@@ -107,6 +111,7 @@ public void setUp() throws InterruptedException, ExecutionException, IOException
 
     bout = new ByteArrayOutputStream();
     out = new PrintStream(bout);
+    originalPrintStream = System.out;
     System.setOut(out);
   }
 
@@ -115,7 +120,8 @@ public void tearDown() throws InterruptedException, ExecutionException, IOExcept
     cleanUpBucket();
     // Delete the created glossary
     DeleteGlossary.deleteGlossary(PROJECT_ID, GLOSSARY_ID);
-    System.setOut(null);
+    System.out.flush();
+    System.setOut(originalPrintStream);
   }
 
   @Test

translate/snippets/src/test/java/com/example/translate/BatchTranslateTextWithGlossaryTests.java

@@ -34,6 +34,7 @@
 import org.junit.After;
 import org.junit.Before;
 import org.junit.BeforeClass;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -55,6 +56,7 @@ public class BatchTranslateTextWithGlossaryTests {
 
   private ByteArrayOutputStream bout;
   private PrintStream out;
+  private PrintStream originalPrintStream;
 
   private static final void cleanUpBucket() {
     Storage storage = StorageOptions.getDefaultInstance().getService();
@@ -106,6 +108,7 @@ public void setUp() throws InterruptedException, ExecutionException, IOException
 
     bout = new ByteArrayOutputStream();
     out = new PrintStream(bout);
+    originalPrintStream = System.out;
     System.setOut(out);
   }
 
@@ -115,9 +118,12 @@ public void tearDown() throws InterruptedException, ExecutionException, IOExcept
     cleanUpBucket();
     // Delete the created glossary
     DeleteGlossary.deleteGlossary(PROJECT_ID, GLOSSARY_ID);
-    System.setOut(null);
+    System.out.flush();
+    System.setOut(originalPrintStream);
   }
 
+  @Rule public Retry retry = new Retry(3);
+
   @Test
   public void testBatchTranslateTextWithGlossary()
       throws InterruptedException, ExecutionException, IOException, TimeoutException {

translate/snippets/src/test/java/com/example/translate/BatchTranslateTextWithModelTests.java

@@ -32,6 +32,7 @@
 import org.junit.After;
 import org.junit.Before;
 import org.junit.BeforeClass;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -50,6 +51,7 @@ public class BatchTranslateTextWithModelTests {
 
   private ByteArrayOutputStream bout;
   private PrintStream out;
+  private PrintStream originalPrintStream;
 
   private static final void cleanUpBucket() {
     Storage storage = StorageOptions.getDefaultInstance().getService();
@@ -93,15 +95,19 @@ public static void checkRequirements() {
   public void setUp() {
     bout = new ByteArrayOutputStream();
     out = new PrintStream(bout);
+    originalPrintStream = System.out;
     System.setOut(out);
   }
 
   @After
   public void tearDown() {
     cleanUpBucket();
-    System.setOut(null);
+    System.out.flush();
+    System.setOut(originalPrintStream);
   }
 
+  @Rule public Retry retry = new Retry(3);
+
   @Test
   public void testBatchTranslateTextWithModel()
       throws InterruptedException, ExecutionException, IOException, TimeoutException {

translate/snippets/src/test/java/com/example/translate/Retry.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.translate;
+
+import java.util.Objects;
+import org.junit.rules.TestRule;
+import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
+
+public class Retry implements TestRule {
+  private int maxAttempts;
+
+  public Retry(int maxAttempts) {
+    this.maxAttempts = maxAttempts;
+  }
+
+  @Override
+  public Statement apply(Statement base, Description description) {
+    return statement(base, description);
+  }
+
+  private Statement statement(final Statement base, final Description description) {
+    return new Statement() {
+      @Override
+      public void evaluate() throws Throwable {
+        Throwable caughtThrowable = null;
+
+        // implement retry logic here
+        int factor = 1;
+        for (int attempt = 0; attempt < maxAttempts; attempt++) {
+          try {
+            base.evaluate();
+            return;
+          } catch (Throwable t) {
+            caughtThrowable = t;
+
+            // random_number_milliseconds that is less than or equal to 1000.
+            int randomNumberMilliseconds = (int) Math.floor(Math.random() * 1000) + 1;
+            Thread.sleep(1300 * factor + randomNumberMilliseconds);
+            System.out.println(description.getDisplayName() + ": run " + (attempt + 1) + " failed");
+            factor += 1;
+
+          }
+        }
+        System.out.println(
+            description.getDisplayName() + ": giving up after " + maxAttempts + " failures");
+        throw Objects.requireNonNull(caughtThrowable);
+      }
+    };
+  }
+}