Create Cronet's CTS for CronetEngine APIs

At the moment CronetCtsTestServer doesn't support QUIC and doesn't
report the negotiated protocol (i.e.,
UrlResponseInfo#getNegotiatedProtocol() will always return "unknown").
To circumenvent that, use "https://source.android.com" as target URL.

Test: atest CtsCronetTestCases
Change-Id: If5bf3d5e8f38675cddabba597db2d64e59cc5b60
diff --git a/Cronet/tests/cts/src/android/net/http/cts/CronetEngineTest.java b/Cronet/tests/cts/src/android/net/http/cts/CronetEngineTest.java
new file mode 100644
index 0000000..7df3890
--- /dev/null
+++ b/Cronet/tests/cts/src/android/net/http/cts/CronetEngineTest.java
@@ -0,0 +1,110 @@
+/*
+ * Copyright (C) 2023 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.net.http.cts;
+
+import static android.net.http.cts.util.TestUtilsKt.assertOKStatusCode;
+import static android.net.http.cts.util.TestUtilsKt.skipIfNoInternetConnection;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.junit.Assert.assertEquals;
+
+import android.content.Context;
+import android.net.http.HttpEngine;
+import android.net.http.UrlRequest;
+import android.net.http.UrlResponseInfo;
+import android.net.http.cts.util.TestUrlRequestCallback;
+import android.net.http.cts.util.TestUrlRequestCallback.ResponseStep;
+
+import androidx.test.platform.app.InstrumentationRegistry;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@RunWith(AndroidJUnit4.class)
+public class CronetEngineTest {
+    private static final String HOST = "source.android.com";
+    private static final String URL = "https://" + HOST;
+
+    private HttpEngine.Builder mEngineBuilder;
+    private TestUrlRequestCallback mCallback;
+    private HttpEngine mEngine;
+
+    @Before
+    public void setUp() throws Exception {
+        Context context = InstrumentationRegistry.getInstrumentation().getContext();
+        skipIfNoInternetConnection(context);
+        mEngineBuilder = new HttpEngine.Builder(context);
+        mCallback = new TestUrlRequestCallback();
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        if (mEngine != null) {
+            mEngine.shutdown();
+        }
+    }
+
+    @Test
+    public void testCronetEngine_Default() throws Exception {
+        mEngine = mEngineBuilder.build();
+        UrlRequest.Builder builder =
+                mEngine.newUrlRequestBuilder(URL, mCallback, mCallback.getExecutor());
+        builder.build().start();
+
+        mCallback.expectCallback(ResponseStep.ON_SUCCEEDED);
+        UrlResponseInfo info = mCallback.mResponseInfo;
+        assertOKStatusCode(info);
+        assertEquals("h2", info.getNegotiatedProtocol());
+    }
+
+    @Test
+    public void testCronetEngine_DisableHttp2() throws Exception {
+        mEngine = mEngineBuilder.setEnableHttp2(false).build();
+        UrlRequest.Builder builder =
+                mEngine.newUrlRequestBuilder(URL, mCallback, mCallback.getExecutor());
+        builder.build().start();
+
+        mCallback.expectCallback(ResponseStep.ON_SUCCEEDED);
+        UrlResponseInfo info = mCallback.mResponseInfo;
+        assertOKStatusCode(info);
+        assertEquals("http/1.1", info.getNegotiatedProtocol());
+    }
+
+    @Test
+    public void testCronetEngine_EnableQuic() throws Exception {
+        // The hint doesn't guarantee that QUIC will win the race, just that it will race TCP.
+        // If this ends up being flaky, consider sending multiple requests.
+        mEngine = mEngineBuilder.setEnableQuic(true).addQuicHint(HOST, 443, 443).build();
+        UrlRequest.Builder builder =
+                mEngine.newUrlRequestBuilder(URL, mCallback, mCallback.getExecutor());
+        builder.build().start();
+
+        mCallback.expectCallback(ResponseStep.ON_SUCCEEDED);
+        UrlResponseInfo info = mCallback.mResponseInfo;
+        assertOKStatusCode(info);
+        assertEquals("h3", info.getNegotiatedProtocol());
+    }
+
+    @Test
+    public void testCronetEngine_GetDefaultUserAgent() throws Exception {
+        assertThat(mEngineBuilder.getDefaultUserAgent(), containsString("AndroidHttpClient"));
+    }
+}