SystemOutWriterTest.java

package org.skywalking.apm.agent.core.logging;

import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;
import org.mockito.Mockito;

import java.io.PrintStream;

import static org.mockito.Matchers.anyString;
import static org.mockito.Mockito.times;

/**
 * Created by wusheng on 2017/2/28.
 */
public class SystemOutWriterTest {
    private static PrintStream outRef;

    @BeforeClass
    public static void initAndHoldOut() {
        outRef = System.out;
    }

    @Test
    public void testWrite() {
        PrintStream mockStream = Mockito.mock(PrintStream.class);
        System.setOut(mockStream);

        SystemOutWriter.INSTANCE.write("hello");

        Mockito.verify(mockStream, times(1)).println(anyString());
    }

    @AfterClass
    public static void reset() {
        System.setOut(outRef);
    }
}