Add LoaderTestCase that makes it easier to test Loaders.

Change-Id: I4e91d6767cfd5cc61d7893e9cd71e963e42601a4

1 files changed, 101 insertions, 0 deletions

diff --git a/test-runner/src/android/test/LoaderTestCase.java b/test-runner/src/android/test/LoaderTestCase.java
new file mode 100644
index 0000000..8be6590
--- /dev/null
+++ b/test-runner/src/android/test/LoaderTestCase.java
@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2010 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 android.test;
+
+import android.content.Loader;
+import android.content.Loader.OnLoadCompleteListener;
+import android.os.AsyncTask;
+import android.os.Handler;
+import android.os.Looper;
+import android.os.Message;
+
+import java.util.concurrent.ArrayBlockingQueue;
+
+/**
+ * A convenience class for testing {@link Loader}s. This test case
+ * provides a simple way to synchronously get the result from a Loader making
+ * it easy to assert that the Loader returns the expected result.
+ */
+public class LoaderTestCase extends AndroidTestCase {
+    static {
+        // Force class loading of AsyncTask on the main thread so that it's handlers are tied to
+        // the main thread and responses from the worker thread get delivered on the main thread.
+        // The tests are run on another thread, allowing them to block waiting on a response from
+        // the code running on the main thread. The main thread can't block since the AysncTask
+        // results come in via the event loop.
+        new AsyncTask<Void, Void, Void>() {
+            @Override
+            protected Void doInBackground(Void... args) {return null;}
+            @Override
+            protected void onPostExecute(Void result) {}
+        };
+    }
+
+    /**
+     * Runs a Loader synchronously and returns the result of the load. The loader will
+     * be started, stopped, and destroyed by this method so it cannot be reused.
+     *
+     * @param loader The loader to run synchronously
+     * @return The result from the loader
+     */
+    public <T> T getLoaderResultSynchronously(final Loader<T> loader) {
+        // The test thread blocks on this queue until the loader puts it's result in
+        final ArrayBlockingQueue<T> queue = new ArrayBlockingQueue<T>(1);
+
+        // This callback runs on the "main" thread and unblocks the test thread
+        // when it puts the result into the blocking queue
+        final OnLoadCompleteListener<T> listener = new OnLoadCompleteListener<T>() {
+            @Override
+            public void onLoadComplete(Loader<T> completedLoader, T data) {
+                // Shut the loader down
+                completedLoader.unregisterListener(this);
+                completedLoader.stopLoading();
+                completedLoader.destroy();
+
+                // Store the result, unblocking the test thread
+                queue.add(data);
+            }
+        };
+
+        // This handler runs on the "main" thread of the process since AsyncTask
+        // is documented as needing to run on the main thread and many Loaders use
+        // AsyncTask
+        final Handler mainThreadHandler = new Handler(Looper.getMainLooper()) {
+            @Override
+            public void handleMessage(Message msg) {
+                loader.registerListener(0, listener);
+                loader.startLoading();
+            }
+        };
+
+        // Ask the main thread to start the loading process
+        mainThreadHandler.sendEmptyMessage(0);
+
+        // Block on the queue waiting for the result of the load to be inserted
+        T result;
+        while (true) {
+            try {
+                result = queue.take();
+                break;
+            } catch (InterruptedException e) {
+                throw new RuntimeException("waiting thread interrupted", e);
+            }
+        }
+
+        return result;
+    }
+}