### Question:
LibraryFunctionMapper extends FunctionMapper { @Nullable @Override public Method resolveFunction(@Nonnull final String namespace, @Nonnull final String functionName) { final Map<String, Method> library = libraries.get(namespace); if (library == null) { return null; } return library.get(functionName); } LibraryFunctionMapper(@Nonnull final Map<String, Class<?>> libraryClasses); @Nullable @Override Method resolveFunction(@Nonnull final String namespace, @Nonnull final String functionName);  }### Answer:
@Test public void testConstruction() { final String key = "tlfm"; final LibraryFunctionMapper mapper = new LibraryFunctionMapper( ImmutableMap.of(key, TestLibraryFunctionMapper.class)); final Method foundMe = mapper.resolveFunction(key, "findMe"); assertNotNull(foundMe); final Method foundMeToo = mapper.resolveFunction(key, "findMeToo"); assertNotNull(foundMeToo); }