Added new Tee class, that works much like Unix's 'tee' command.

      
I needed it to debug the IPython sphinx directive (next commit).
      
Also fixed some typos along the way.

IPython/testing/decorators.py

@@ -60,9 +60,9 b' import nosepatch # monkeypatch nose'
 
 # We already have python3-compliant code for parametric tests
 if sys.version[0]=='2':
-    from _paramtestpy2 import parametric
+    from _paramtestpy2 import parametric, ParametricTestCase
 else:
-    from _paramtestpy3 import parametric
+    from _paramtestpy3 import parametric, ParametricTestCase
 
 # Expose the unittest-driven decorators
 from ipunittest import ipdoctest, ipdocstring

IPython/utils/genutils.py

@@ -105,6 +105,65 b" if sys.platform == 'win32' and readline.have_readline:"
     Term = IOTerm(cout=readline._outputfile,cerr=readline._outputfile)
 
 
+class Tee(object):
+    """A class to duplicate an output stream to stdout/err.
+
+    This works in a manner very similar to the Unix 'tee' command.
+
+    When the object is closed or deleted, it closes the original file given to
+    it for duplication.
+    """
+    # Inspired by:
+    # http://mail.python.org/pipermail/python-list/2007-May/442737.html
+
+    def __init__(self, file, mode=None, channel='stdout'):
+        """Construct a new Tee object.
+
+        Parameters
+        ----------
+        file : filename or open filehandle (writable)
+          File that will be duplicated
+
+        mode : optional, valid mode for open().
+          If a filename was give, open with this mode.
+
+        channel : str, one of ['stdout', 'stderr']  
+        """
+        if channel not in ['stdout', 'stderr']:
+            raise ValueError('Invalid channel spec %s' % channel)
+        
+        if hasattr(file, 'write') and hasattr(file, 'seek'):
+            self.file = file
+        else:
+            self.file = open(name, mode)
+        self.channel = channel
+        self.ostream = getattr(sys, channel)
+        setattr(sys, channel, self)
+        self._closed = False
+
+    def close(self):
+        """Close the file and restore the channel."""
+        self.flush()
+        setattr(sys, self.channel, self.ostream)
+        self.file.close()
+        self._closed = True
+
+    def write(self, data):
+        """Write data to both channels."""
+        self.file.write(data)
+        self.ostream.write(data)
+        self.ostream.flush()
+
+    def flush(self):
+        """Flush both channels."""
+        self.file.flush()
+        self.ostream.flush()
+
+    def __del__(self):
+        if not self._closed:
+            self.close()
+        
+
 #****************************************************************************
 # Generic warning/error printer, used by everything else
 def warn(msg,level=2,exit_val=1):

IPython/utils/tests/test_genutils.py

@@ -20,7 +20,9 b' import os'
 import shutil
 import sys
 import tempfile
+import unittest
 
+from cStringIO import StringIO
 from os.path import join, abspath, split
 
 # third-party
@@ -32,6 +34,7 b' from nose.tools import raises'
 # Our own
 import IPython
 from IPython.utils import genutils
+from IPython.testing import decorators as dec
 from IPython.testing.decorators import skipif, skip_if_not_win32
 
 # Platform-dependent imports
@@ -107,7 +110,7 b' def teardown_environment():'
         (wreg.OpenKey, wreg.QueryValueEx,) = platformstuff
 
 # Build decorator that uses the setup_environment/setup_environment
-with_enivronment = with_setup(setup_environment, teardown_environment)
+with_environment = with_setup(setup_environment, teardown_environment)
 
 
 #
@@ -115,7 +118,7 b' with_enivronment = with_setup(setup_environment, teardown_environment)'
 #
 
 @skip_if_not_win32
-@with_enivronment
+@with_environment
 def test_get_home_dir_1():
     """Testcase for py2exe logic, un-compressed lib
     """
@@ -128,7 +131,7 b' def test_get_home_dir_1():'
     nt.assert_equal(home_dir, abspath(HOME_TEST_DIR))
     
 @skip_if_not_win32
-@with_enivronment
+@with_environment
 def test_get_home_dir_2():
     """Testcase for py2exe logic, compressed lib
     """
@@ -139,14 +142,14 b' def test_get_home_dir_2():'
     home_dir = genutils.get_home_dir()
     nt.assert_equal(home_dir, abspath(HOME_TEST_DIR).lower())
 
-@with_enivronment
+@with_environment
 def test_get_home_dir_3():
     """Testcase $HOME is set, then use its value as home directory."""
     env["HOME"] = HOME_TEST_DIR
     home_dir = genutils.get_home_dir()
     nt.assert_equal(home_dir, env["HOME"])
 
-@with_enivronment
+@with_environment
 def test_get_home_dir_4():
     """Testcase $HOME is not set, os=='poix'. 
     This should fail with HomeDirError"""
@@ -156,7 +159,7 b' def test_get_home_dir_4():'
     nt.assert_raises(genutils.HomeDirError, genutils.get_home_dir)
         
 @skip_if_not_win32
-@with_enivronment
+@with_environment
 def test_get_home_dir_5():
     """Testcase $HOME is not set, os=='nt' 
     env['HOMEDRIVE'],env['HOMEPATH'] points to path."""
@@ -169,7 +172,7 b' def test_get_home_dir_5():'
     nt.assert_equal(home_dir, abspath(HOME_TEST_DIR))
 
 @skip_if_not_win32
-@with_enivronment
+@with_environment
 def test_get_home_dir_6():
     """Testcase $HOME is not set, os=='nt' 
     env['HOMEDRIVE'],env['HOMEPATH'] do not point to path.
@@ -186,7 +189,7 b' def test_get_home_dir_6():'
 
 # Should we stub wreg fully so we can run the test on all platforms?
 @skip_if_not_win32
-@with_enivronment
+@with_environment
 def test_get_home_dir_7():
     """Testcase $HOME is not set, os=='nt' 
     env['HOMEDRIVE'],env['HOMEPATH'], env['USERPROFILE'] missing
@@ -214,7 +217,7 b' def test_get_home_dir_7():'
 # Tests for get_ipython_dir
 #
 
-@with_enivronment
+@with_environment
 def test_get_ipython_dir_1():
     """test_get_ipython_dir_1, Testcase to see if we can call get_ipython_dir without Exceptions."""
     env['IPYTHONDIR'] = "someplace/.ipython"
@@ -222,7 +225,7 b' def test_get_ipython_dir_1():'
     nt.assert_equal(ipdir, "someplace/.ipython")
 
 
-@with_enivronment
+@with_environment
 def test_get_ipython_dir_2():
     """test_get_ipython_dir_2, Testcase to see if we can call get_ipython_dir without Exceptions."""
     genutils.get_home_dir = lambda : "someplace"
@@ -283,3 +286,38 b' def test_filefind():'
 def test_get_ipython_package_dir():
     ipdir = genutils.get_ipython_package_dir()
     nt.assert_true(os.path.isdir(ipdir))
+
+
+def test_tee_simple():
+    "Very simple check with stdout only"
+    chan = StringIO()
+    text = 'Hello'
+    tee = genutils.Tee(chan, channel='stdout')
+    print >> chan, text,
+    nt.assert_equal(chan.getvalue(), text)
+
+
+class TeeTestCase(dec.ParametricTestCase):
+
+    def tchan(self, channel, check='close'):
+        trap = StringIO()
+        chan = StringIO()
+        text = 'Hello'
+        
+        std_ori = getattr(sys, channel)
+        setattr(sys, channel, trap)
+
+        tee = genutils.Tee(chan, channel=channel)
+        print >> chan, text,
+        setattr(sys, channel, std_ori)
+        trap_val = trap.getvalue()
+        nt.assert_equals(chan.getvalue(), text)
+        if check=='close':
+            tee.close()
+        else:
+            del tee
+
+    def test(self):
+        for chan in ['stdout', 'stderr']:
+            for check in ['close', 'del']:
+                yield self.tchan(chan, check)