it.ozimov.cirneco.hamcrest.number.IsNegativeInfinity Maven / Gradle / Ivy

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package it.ozimov.cirneco.hamcrest.number;

import org.hamcrest.Description;
import org.hamcrest.Matcher;
import org.hamcrest.TypeSafeMatcher;


/**
 * Is the value a number with negative infinite value?
 *
 * @since version 0.1 for JDK7
 */
public class IsNegativeInfinity extends TypeSafeMatcher {

    /**
     * Creates a matcher for {@code N} that matches when the number is a {@linkplain Double}
     * or {@linkplain Float} with value equal to NEGATIVE_INFINITY.
     * 
     * For example:
     * 
assertThat(Float.NegativeInfinity, negativeInfinity())
     * will return true.
     * while:
     * assertThat(10, negativeInfinity())
     * assertThat(Double.PositiveInfinity, negativeInfinity())
     * will both return false.
     */
    public static  Matcher negativeInfinity() {
        return new IsNegativeInfinity<>();
    }

    @Override
    protected boolean matchesSafely(final N number) {
        if (number instanceof Double) {
            return ((Double) number).compareTo(Double.NEGATIVE_INFINITY) == 0;
        } else if (number instanceof Float) {
            return ((Float) number).compareTo(Float.NEGATIVE_INFINITY) == 0;
        }
        return false;
    }

    @Override
    protected void describeMismatchSafely(final N item, final Description mismatchDescription) {
        mismatchDescription.appendValue(item)
                .appendText(" is not negative infinity");
    }

    @Override
    public void describeTo(final Description description) {
        description.appendText("a value equals to negative infinity");
    }

}