common/src/test/java/org/apache/nemo/common/StateMachineTest.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.nemo.common;

import org.apache.nemo.common.exception.IllegalStateTransitionException;
import org.junit.Before;
import org.junit.Test;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

/**
 * Tests {@link StateMachine}
 */
public final class StateMachineTest {
  private StateMachine.Builder stateMachineBuilder;

  @Before
  public void setUp() {
    this.stateMachineBuilder = StateMachine.newBuilder();
  }

  @Test
  public void testSimpleStateTransitions() throws IllegalStateTransitionException {
    stateMachineBuilder.addState(CookingState.SHOPPING, "Shopping for ingredients");
    stateMachineBuilder.addState(CookingState.PREPARING, "Washing vegetables, chopping meat...");
    stateMachineBuilder.addState(CookingState.SEASONING, "Adding salt and pepper");
    stateMachineBuilder.addState(CookingState.COOKING, "The food is in the oven");
    stateMachineBuilder.addState(CookingState.READY_TO_EAT, "Let's eat");

    stateMachineBuilder.addTransition(CookingState.SHOPPING, CookingState.PREPARING, "");
    stateMachineBuilder.addTransition(CookingState.PREPARING, CookingState.SEASONING, "");
    stateMachineBuilder.addTransition(CookingState.SEASONING, CookingState.COOKING, "");
    stateMachineBuilder.addTransition(CookingState.COOKING, CookingState.READY_TO_EAT, "");

    stateMachineBuilder.setInitialState(CookingState.SHOPPING);

    final StateMachine stateMachine = stateMachineBuilder.build();

    assertEquals(CookingState.SHOPPING, stateMachine.getCurrentState());
    assertTrue(stateMachine.compareAndSetState(CookingState.SHOPPING, CookingState.PREPARING));

    assertEquals(CookingState.PREPARING, stateMachine.getCurrentState());
    assertTrue(stateMachine.compareAndSetState(CookingState.PREPARING, CookingState.SEASONING));

    assertEquals(CookingState.SEASONING, stateMachine.getCurrentState());
    assertTrue(stateMachine.compareAndSetState(CookingState.SEASONING, CookingState.COOKING));

    assertEquals(CookingState.COOKING, stateMachine.getCurrentState());
    assertTrue(stateMachine.compareAndSetState(CookingState.COOKING, CookingState.READY_TO_EAT));
  }

  private enum CookingState {
    SHOPPING,
    PREPARING,
    SEASONING,
    COOKING,
    READY_TO_EAT
  }
}