Re: Reading from stdout

From:

Daniel Pitts <newsgroup.nospam@virtualinfinity.net>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 12 Sep 2013 10:56:49 -0700

Message-ID:

<DfnYt.29309$cs5.9201@fx09.iad>

On 9/12/13 9:59 AM, White Spirit wrote:

I'm writing a unit test for a logger class that writes to stdout. The
logger class uses an OutputStreamWriter to wrap FileDescriptor.out:

   mOut = new OutputStreamWriter(new
FileOutputStream(FileDescriptor.out), "UTF-8");

My unit test instantiates the logger class as a local object. When I
try to read from FileDescriptor.out in my unit test class, however,
nothing is received:

  BufferedReader reader = new BufferedReader( new InputStreamReader( new
FileInputStream( FileDescriptor.out ) ) );
  // do some logging
  // ...
  String n = reader.readLine();

Is there any way of reading what the logger is outputting?

If you allow the Logger to accept an OutputStream, then you can pass in
a new ByteArrayOutputStream().

  final ByteArrayOutputStream baos = new ByteArrayOutputStream();
  final Logger logger = new Logger(baos);
  doSomeLogging(logger);
  String result = baos.toString(); // uses default encoding.
  assertEqual(expectedResult, result);