1 files changed, 86 insertions, 0 deletions
diff --git a/src/test/java/com/google/android/downloader/TestingExecutorService.java b/src/test/java/com/google/android/downloader/TestingExecutorService.java
new file mode 100644
index 0000000..2fa6b40
--- /dev/null
+++ b/src/test/java/com/google/android/downloader/TestingExecutorService.java
@@ -0,0 +1,86 @@
+// Copyright 2021 The Android Open Source Project
+//
+// 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.google.android.downloader;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import com.google.common.util.concurrent.AbstractListeningExecutorService;
+import java.util.ArrayDeque;
+import java.util.List;
+import java.util.Queue;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Implementation of {@link com.google.common.util.concurrent.ListeningExecutorService} for testing
+ * purposes. It artificially delays runnables enqueued via calls to {@link #execute} to allow tests
+ * to exercise async behavior.
+ */
+final class TestingExecutorService extends AbstractListeningExecutorService {
+  private final ExecutorService delegate;
+  private final Queue<Runnable> taskQueue = new ArrayDeque<>();
+
+  private boolean paused = false;
+
+  TestingExecutorService(ExecutorService delegate) {
+    this.delegate = delegate;
+  }
+
+  @Override
+  public void shutdown() {
+    delegate.shutdown();
+  }
+
+  @Override
+  public List<Runnable> shutdownNow() {
+    return delegate.shutdownNow();
+  }
+
+  @Override
+  public boolean isShutdown() {
+    return delegate.isShutdown();
+  }
+
+  @Override
+  public boolean isTerminated() {
+    return delegate.isTerminated();
+  }
+
+  @Override
+  public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException {
+    return delegate.awaitTermination(timeout, unit);
+  }
+
+  public synchronized void pause() {
+    paused = true;
+  }
+
+  public synchronized void resume() {
+    paused = false;
+    while (!taskQueue.isEmpty()) {
+      delegate.execute(checkNotNull(taskQueue.poll()));
+    }
+  }
+
+  @Override
+  public void execute(Runnable command) {
+    if (paused) {
+      taskQueue.add(command);
+      return;
+    }
+
+    delegate.execute(command);
+  }
+}