Introducing FallbackJSBundleLoader

Reviewed By: michalgr

Differential Revision: D4386951

fbshipit-source-id: b1375deee9b3268d414e1b03fa79df50ac4d36cb

ReactAndroid/src/test/java/com/facebook/react/cxxbridge/BUCK

@@ -0,0 +1,18 @@
+include_defs('//ReactAndroid/DEFS')
+
+rn_robolectric_test(
+  name = 'cxxbridge',
+  # Please change the contact to the oncall of your team
+  contacts = ['oncall+fbandroid_sheriff@xmail.facebook.com'],
+  srcs = glob(['*Test.java']),
+  deps = [
+    react_native_dep('third-party/java/fest:fest'),
+    react_native_dep('third-party/java/junit:junit'),
+    react_native_dep('third-party/java/mockito:mockito'),
+    react_native_dep('third-party/java/robolectric3/robolectric:robolectric'),
+    react_native_target('java/com/facebook/react/cxxbridge:bridge'),
+  ],
+  visibility = [
+    'PUBLIC'
+  ],
+)

ReactAndroid/src/test/java/com/facebook/react/cxxbridge/FallbackJSBundleLoaderTest.java

@@ -0,0 +1,154 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.cxxbridge;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.fest.assertions.api.Assertions.assertThat;
+import static org.fest.assertions.api.Assertions.fail;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+public class FallbackJSBundleLoaderTest {
+
+  private static final String UNRECOVERABLE;
+  static {
+    String prefix = FallbackJSBundleLoader.RECOVERABLE;
+    char first = prefix.charAt(0);
+
+    UNRECOVERABLE = prefix.replace(first, (char) (first + 1));
+  }
+
+  @Test
+  public void firstLoaderSucceeds() {
+    JSBundleLoader delegates[] = new JSBundleLoader[] {
+      successfulLoader("url1"),
+      successfulLoader("url2")
+    };
+
+    FallbackJSBundleLoader fallbackLoader =
+      new FallbackJSBundleLoader(new ArrayList<>(Arrays.asList(delegates)));
+
+    assertThat(fallbackLoader.loadScript(null)).isEqualTo("url1");
+
+    verify(delegates[0], times(1)).loadScript(null);
+    verify(delegates[1], never()).loadScript(null);
+  }
+
+  @Test
+  public void fallingBackSuccessfully() {
+    JSBundleLoader delegates[] = new JSBundleLoader[] {
+      recoverableLoader("url1", "error1"),
+      successfulLoader("url2"),
+      successfulLoader("url3")
+    };
+
+    FallbackJSBundleLoader fallbackLoader =
+      new FallbackJSBundleLoader(new ArrayList<>(Arrays.asList(delegates)));
+
+    assertThat(fallbackLoader.loadScript(null)).isEqualTo("url2");
+
+    verify(delegates[0], times(1)).loadScript(null);
+    verify(delegates[1], times(1)).loadScript(null);
+    verify(delegates[2], never()).loadScript(null);
+  }
+
+  @Test
+  public void fallingbackUnsuccessfully() {
+    JSBundleLoader delegates[] = new JSBundleLoader[] {
+      recoverableLoader("url1", "error1"),
+      recoverableLoader("url2", "error2")
+    };
+
+    FallbackJSBundleLoader fallbackLoader =
+      new FallbackJSBundleLoader(new ArrayList<>(Arrays.asList(delegates)));
+
+    try {
+      fallbackLoader.loadScript(null);
+      fail("expect throw");
+    } catch (Exception e) {
+      assertThat(e).isInstanceOf(RuntimeException.class);
+
+      Throwable cause = e.getCause();
+      ArrayList<String> msgs = new ArrayList<>();
+      while (cause != null) {
+        msgs.add(cause.getMessage());
+        cause = cause.getCause();
+      }
+
+      assertThat(msgs).containsExactly(
+        recoverableMsg("error1"),
+        recoverableMsg("error2"));
+    }
+
+    verify(delegates[0], times(1)).loadScript(null);
+    verify(delegates[1], times(1)).loadScript(null);
+  }
+
+  @Test
+  public void unrecoverable() {
+    JSBundleLoader delegates[] = new JSBundleLoader[] {
+      fatalLoader("url1", "error1"),
+      recoverableLoader("url2", "error2")
+    };
+
+    FallbackJSBundleLoader fallbackLoader =
+      new FallbackJSBundleLoader(new ArrayList(Arrays.asList(delegates)));
+
+    try {
+      fallbackLoader.loadScript(null);
+      fail("expect throw");
+    } catch (Exception e) {
+      assertThat(e.getMessage()).isEqualTo(fatalMsg("error1"));
+    }
+
+    verify(delegates[0], times(1)).loadScript(null);
+    verify(delegates[1], never()).loadScript(null);
+  }
+
+  private static JSBundleLoader successfulLoader(String url) {
+    JSBundleLoader loader = mock(JSBundleLoader.class);
+    when(loader.loadScript(null)).thenReturn(url);
+
+    return loader;
+  }
+
+  private static String recoverableMsg(String errMsg) {
+    return FallbackJSBundleLoader.RECOVERABLE + errMsg;
+  }
+
+  private static JSBundleLoader recoverableLoader(String url, String errMsg) {
+    JSBundleLoader loader = mock(JSBundleLoader.class);
+    when(loader.loadScript(null))
+      .thenThrow(new RuntimeException(FallbackJSBundleLoader.RECOVERABLE + errMsg));
+
+    return loader;
+  }
+
+  private static String fatalMsg(String errMsg) {
+    return UNRECOVERABLE + errMsg;
+  }
+
+  private static JSBundleLoader fatalLoader(String url, String errMsg) {
+    JSBundleLoader loader = mock(JSBundleLoader.class);
+    when(loader.loadScript(null))
+      .thenThrow(new RuntimeException(UNRECOVERABLE + errMsg));
+
+    return loader;
+  }
+}