InputStream のカスタム Matcher

InputStreamTest.java

package sample;

import static sample.InputStreamTest.InputStreamMatchers.*;
import static org.hamcrest.CoreMatchers.*;
import static org.junit.Assert.*;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;

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

public class InputStreamTest {

    @Test
    public void test() throws Exception {
        InputStream expected = new ByteArrayInputStream("hoge".getBytes());
        InputStream actual = new ByteArrayInputStream("hoge".getBytes());
        assertThat(actual, is(equalTo(expected)));
    }

    public static class InputStreamMatchers {

        public static Matcher<InputStream> equalTo(final InputStream expected) {
            return new TypeSafeMatcher<InputStream>() {

                private byte[] left, right;

                @Override
                protected boolean matchesSafely(InputStream actual) {
                    try {
                        left = read(actual);
                        right = read(expected);
                        return Arrays.equals(left, right);

                    } catch (IOException e) {
                    }
                    return false;
                }

                @Override
                public void describeTo(Description description) {
                    description.appendValue(new String(right));
                }

                @Override
                protected void describeMismatchSafely(InputStream actual, Description mismatchDescription) {
                    mismatchDescription.appendValue(new String(left));
                }
            };
        }

        private static byte[] read(InputStream input) throws IOException {
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            byte[] buff = new byte[1024];
            while (true) {
                int length = input.read(buff);
                if (length < 0) break;
                out.write(buff, 0, length);
            }
            return out.toByteArray();
        }
    }

}