org.junit.contrib.java.lang.system

Class StandardErrorStreamLog

java.lang.Object

org.junit.rules.ExternalResource

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

org.junit.contrib.java.lang.system.StandardErrorStreamLog

All Implemented Interfaces:

org.junit.rules.TestRule

public class StandardErrorStreamLog
extends PrintStreamLog

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

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

     @Test
     public void captureErrorStream() {
       System.err.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 error stream.

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

Prevent output to the standard error stream

In general it is not necessary that a test writes to the standard error 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 StandardErrorStreamLog log = new StandardErrorStreamLog(LOG_ONLY);

Constructor Summary

Constructors

Constructor and Description
StandardErrorStreamLog() Creates a rule that records writes while they are still written to the standard error stream.
StandardErrorStreamLog(LogMode mode) Creates a rule that records writes to the standard error 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

StandardErrorStreamLog

public StandardErrorStreamLog()

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

StandardErrorStreamLog

public StandardErrorStreamLog(LogMode mode)

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

Parameters:

mode - how the rule handles writes to the standard error 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