user/test/com/google/gwt/emultest/java8/util/OptionalTest.java

/*
 * Copyright 2015 Google Inc.
 *
 * 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 com.google.gwt.emultest.java8.util;

import com.google.gwt.junit.client.GWTTestCase;

/**
 * Tests for Optional JRE emulation.
 */
public class OptionalTest extends GWTTestCase {

  @Override
  public String getModuleName() {
    return "com.google.gwt.emultest.EmulSuite";
  }

  public void testSomething() {
    try {
      requireNonNull(null, () -> "Must not be null");
      fail("must throw NPE");
    } catch (NullPointerException e) {
      // expected
    }
  }

  private static <T> T requireNonNull(T obj, Supplier<String> messageSupplier) {
    if (obj == null) {
      throw new NullPointerException(messageSupplier.get());
    }
    return obj;
  }

  @FunctionalInterface
  private interface Supplier<T> {
    T get();
  }
}