it.ozimov.cirneco.hamcrest.base.IsEquivalent Maven / Gradle / Ivy

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package it.ozimov.cirneco.hamcrest.base;

import com.google.common.base.Equivalence;
import org.hamcrest.Description;
import org.hamcrest.Matcher;
import org.hamcrest.TypeSafeMatcher;

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


/**
 * Is the value equivalent to another value as specified by the provided {@linkplain Equivalence}?
 *
 * @since version 0.1 for JDK7
 */
public class IsEquivalent extends TypeSafeMatcher {

    private final T comparison;

    private final Equivalence equivalence;

    /**
     * Creates an instance of the class. comparison can be null,
     * while equivalence cannot.
     */
    public IsEquivalent(final T comparison, final Equivalence equivalence) {
        checkNotNull(equivalence);

        this.comparison = comparison;
        this.equivalence = equivalence;
    }

    /**
     * Creates a matcher that matches when the examined object of type T
     * is equivalent to the specified comparison object according to
     * the provided {@linkplain Equivalence}.
     * 
     * 
Observe that the {@linkplain Equivalence} can deal with nulls.
     */
    public static  Matcher equivalentTo(final T expected, final Equivalence equivalence) {
        return new IsEquivalent<>(expected, equivalence);
    }

    @Override
    protected boolean matchesSafely(final T actual) {
        return equivalence.equivalent(actual, comparison);
    }

    @Override
    protected void describeMismatchSafely(final T item, final Description mismatchDescription) {
        mismatchDescription.appendValue(item)
                .appendText(" is not equivalent to ");
        if (comparison == null) {
            mismatchDescription.appendText("null value");
        } else {
            mismatchDescription.appendValue(comparison);
        }
        mismatchDescription.appendText(" according with Equivalence ")
                .appendValue(equivalence);
    }

    @Override
    public void describeTo(final Description description) {
        description
                .appendText("a value equivalent to ")
                .appendValue(comparison)
                .appendText(" according with Equivalence ")
                .appendValue(equivalence);
    }

}