org.junit.contrib.java.lang.system

Class StandardOutputStreamLog

java.lang.Object

org.junit.rules.ExternalResource

org.junit.contrib.java.lang.system.internal.PrintStreamLog

org.junit.contrib.java.lang.system.StandardOutputStreamLog

All Implemented Interfaces:

org.junit.rules.TestRule

public class StandardOutputStreamLog
extends PrintStreamLog

The StandardOutputStreamLog records writes to the standard output stream. The text written is available via PrintStreamLog.getLog().

   public void MyTest {
     @Rule
     public final StandardOutputStreamLog log = new StandardOutputStreamLog();

     @Test
     public void captureOutputStream() {
       System.out.print("hello world");
       assertEquals("hello world", log.getLog());
     }
   }
 

You can clear the log if you only want to test parts of the text written to the standard output stream.

   @Test
   public void captureOutputStream() {
     System.out.print("before");
     log.clear();
     System.out.print("afterwards");
     assertEquals("afterwards", log.getLog());
   }
 

Prevent output to the standard output stream

In general it is not necessary that a test writes to the standard output stream. Avoiding this output may speed up the test and reduce the clutter on the commandline.

The test does not write to the stream if the rule is created with the LogMode.LOG_ONLY mode.

 @Rule
 public final StandardOutputStreamLog log = new StandardOutputStreamLog(LOG_ONLY);

Constructor Summary

Constructors

Constructor and Description
StandardOutputStreamLog() Creates a rule that records writes while they are still written to the standard output stream.
StandardOutputStreamLog(LogMode mode) Creates a rule that records writes to the standard output stream according to the specified LogMode.

Method Summary

Modifier and Type	Method and Description
protected java.io.PrintStream	getOriginalStream()
protected void	setStream(java.io.PrintStream wrappedLog)

Methods inherited from class org.junit.contrib.java.lang.system.internal.PrintStreamLog

after, before, clear, getLog

Methods inherited from class org.junit.rules.ExternalResource

apply

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StandardOutputStreamLog

public StandardOutputStreamLog()

Creates a rule that records writes while they are still written to the standard output stream.

StandardOutputStreamLog

public StandardOutputStreamLog(LogMode mode)

Creates a rule that records writes to the standard output stream according to the specified LogMode.

Parameters:

mode - how the rule handles writes to the standard output stream.

Throws:

java.lang.NullPointerException - if mode is null.

Method Detail

getOriginalStream

protected java.io.PrintStream getOriginalStream()

Specified by:

getOriginalStream in class PrintStreamLog

setStream

protected void setStream(java.io.PrintStream wrappedLog)

Specified by:

setStream in class PrintStreamLog