flink-spector-master/flinkspector-core/src/main/java/io/flinkspector/core/quantify/records/OutputWithSize.java
/*
 * Copyright 2015 Otto (GmbH & Co KG)
 *
 * 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 io.flinkspector.core.quantify.records;

import com.google.common.collect.Iterables;
import org.hamcrest.Description;
import org.hamcrest.Matcher;
import org.hamcrest.TypeSafeDiagnosingMatcher;
import org.hamcrest.core.IsEqual;

/**
 * Provides a matcher for output that matches when the <code>size</code> of the output
 * satisfies the specified matcher.
 *
 * @param <T> Generic type of the output
 */
public class OutputWithSize<T> extends TypeSafeDiagnosingMatcher<Iterable<T>> {

    Matcher<? super Integer> sizeMatcher;

    public OutputWithSize(Matcher<? super Integer> sizeMatcher) {
        this.sizeMatcher = sizeMatcher;
    }

    public static <T> OutputWithSize<T> outputWithSize(Matcher<? super Integer> sizeMatcher) {
        return new OutputWithSize<T>(sizeMatcher);
    }

    public static <T> OutputWithSize<T> outputWithSize(int size) {
        return OutputWithSize.<T>outputWithSize(IsEqual.equalTo(size));
    }

    @Override
    protected boolean matchesSafely(Iterable<T> item, Description mismatchDescription) {
        int size = Iterables.size(item);
        boolean matches = sizeMatcher.matches(size);
        if (!matches) {
            sizeMatcher.describeMismatch(size, mismatchDescription);
        }
        return matches;
    }

    @Override
    public void describeTo(Description description) {
        description.appendText("output with size: ");
        sizeMatcher.describeTo(description);
    }
}
