UnsatisfiedLinkError when unit testing WritableNativeMap

You can also use JavaOnlyMap, it implements both WritableMap and ReadableMap.

So wherever you need to use Arguments.createMap(), just replace with new JavaOnlyMap()

reference: https://github.com/facebook/react-native/blob/master/ReactAndroid/src/main/java/com/facebook/react/bridge/JavaOnlyMap.java

I don't think you can avoid mocking the Arguments methods in a unit test (though I believe you do not need to do so in an instrumentation test).

In Facebook's own tests, they use PowerMockito to mock them: https://github.com/facebook/react-native/blob/master/ReactAndroid/src/test/java/com/facebook/react/RootViewTest.java#L67

Interesting bits:

PowerMockito.mockStatic(Arguments.class);
PowerMockito.when(Arguments.createArray()).thenAnswer(new Answer<Object>() {
  @Override
  public Object answer(InvocationOnMock invocation) throws Throwable {
    return new JavaOnlyArray();
  }
});
PowerMockito.when(Arguments.createMap()).thenAnswer(new Answer<Object>() {
  @Override
  public Object answer(InvocationOnMock invocation) throws Throwable {
    return new JavaOnlyMap();
  }
});

Also note that this requires you to modify your build.gradle to include these mocking tools: https://github.com/facebook/react-native/blob/master/ReactAndroid/build.gradle#L266

dependencies {
  ...
  testCompile "org.powermock:powermock-api-mockito:${POWERMOCK_VERSION}"
  testCompile "org.powermock:powermock-module-junit4-rule:${POWERMOCK_VERSION}"
  testCompile "org.powermock:powermock-classloading-xstream:${POWERMOCK_VERSION}"
  testCompile "org.mockito:mockito-core:${MOCKITO_CORE_VERSION}"
  testCompile "org.easytesting:fest-assert-core:${FEST_ASSERT_CORE_VERSION}"
  testCompile "org.robolectric:robolectric:${ROBOLECTRIC_VERSION}"
  ...
}

The versions they use can be found in their gradle.properties file.

I don't know how stable these test configurations will be over the long run, but this configuration has let me work with ReadableMap/Array and WritableMap/Array in unit tests.