test/langtools/jdk/jshell/PipeInputStreamTest.java

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/*
 * @test 8167461
 * @summary Verify PipeInputStream works.
 * @modules jdk.compiler/com.sun.tools.javac.util
 *          jdk.jshell/jdk.jshell.execution:open
 * @run testng PipeInputStreamTest
 */

import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

import org.testng.annotations.Test;

import com.sun.tools.javac.util.Pair;

import static org.testng.Assert.*;

@Test
public class PipeInputStreamTest {

    public void testReadArrayNotBlocking() throws Exception {
        Pair<InputStream, OutputStream> streams = createPipeStream();
        InputStream in = streams.fst;
        OutputStream out = streams.snd;
        out.write('a');
        byte[] data = new byte[12];
        assertEquals(in.read(data), 1);
        assertEquals(data[0], 'a');
        out.write('a'); out.write('b'); out.write('c');
        assertEquals(in.read(data), 3);
        assertEquals(data[0], 'a');
        assertEquals(data[1], 'b');
        assertEquals(data[2], 'c');
    }

    private Pair<InputStream, OutputStream> createPipeStream() throws Exception {
        Class<?> pipeStreamClass = Class.forName("jdk.jshell.execution.PipeInputStream");
        Constructor<?> c = pipeStreamClass.getDeclaredConstructor();
        c.setAccessible(true);
        Object pipeStream = c.newInstance();
        Method createOutputStream = pipeStreamClass.getDeclaredMethod("createOutput");
        createOutputStream.setAccessible(true);
        return Pair.of((InputStream) pipeStream, (OutputStream) createOutputStream.invoke(pipeStream));
    }

}