com.google.cloud.dataflow.sdk.runners.inprocess.MockClock.java Source code

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Here is the source code for com.google.cloud.dataflow.sdk.runners.inprocess.MockClock.java

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/*
 * Copyright (C) 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.cloud.dataflow.sdk.runners.inprocess;

import static com.google.common.base.Preconditions.checkArgument;

import org.joda.time.Duration;
import org.joda.time.Instant;

/**
 * A clock that returns a constant value for now which can be set with calls to
 * {@link #set(Instant)}.
 *
 * <p>For uses of the {@link Clock} interface in unit tests.
 */
public class MockClock implements Clock {

    private Instant now;

    public static MockClock fromInstant(Instant initial) {
        return new MockClock(initial);
    }

    private MockClock(Instant initialNow) {
        this.now = initialNow;
    }

    public void set(Instant newNow) {
        checkArgument(!newNow.isBefore(now), "Cannot move MockClock backwards in time from %s to %s", now, newNow);
        this.now = newNow;
    }

    public void advance(Duration duration) {
        checkArgument(duration.getMillis() > 0, "Cannot move MockClock backwards in time by duration %s", duration);
        set(now.plus(duration));
    }

    @Override
    public Instant now() {
        return now;
    }

}