public void testfieldImplicitWrite() throws Exception {
    PlatformTestUtil.registerExtension(
        ImplicitUsageProvider.EP_NAME,
        new ImplicitUsageProvider() {
          @Override
          public boolean isImplicitUsage(PsiElement element) {
            return isImplicitWrite(element);
          }

          @Override
          public boolean isImplicitRead(PsiElement element) {
            return false;
          }

          @Override
          public boolean isImplicitWrite(PsiElement element) {
            return element instanceof PsiField
                && "implicitWrite".equals(((PsiNamedElement) element).getName());
          }
        },
        getTestRootDisposable());

    doTest();
  }
 public static <T> void registerExtension(
     final ExtensionPointName<T> name, final T t, final Disposable parentDisposable) {
   registerExtension(Extensions.getRootArea(), name, t, parentDisposable);
 }