[svn r37872] StdCaptureFD and StdCapture now try

to take care of stdin in a mostly uniform way.

--HG--
branch : trunk

py/io/stdcapture.py

@@ -4,7 +4,6 @@ import py
 try: from cStringIO import StringIO
 except ImportError: from StringIO import StringIO
 
-emptyfile = StringIO()
 
 class Capture(object):
     def call(cls, func, *args, **kwargs): 
@@ -33,10 +32,17 @@ class Capture(object):
 
 
 class StdCaptureFD(Capture): 
-    """ capture Stdout and Stderr both on filedescriptor 
-        and sys.stdout/stderr level. 
+    """ This class allows to capture writes to FD1 and FD2 
+        and may connect a NULL file to FD0 (and prevent
+        reads from sys.stdin)
     """
-    def __init__(self, out=True, err=True, mixed=False, patchsys=True): 
+    def __init__(self, out=True, err=True, mixed=False, in_=True, patchsys=True): 
+        if in_:
+            self._oldin = (sys.stdin, os.dup(0))
+            sys.stdin  = DontReadFromInput()
+            fd = os.open(devnullpath, os.O_RDONLY)
+            os.dup2(fd, 0)
+            os.close(fd)
         if out: 
             self.out = py.io.FDCapture(1) 
             if patchsys: 
@@ -57,17 +63,23 @@ class StdCaptureFD(Capture):
             outfile = self.out.done() 
         if hasattr(self, 'err'): 
             errfile = self.err.done() 
+        if hasattr(self, '_oldin'):
+            oldsys, oldfd = self._oldin 
+            os.dup2(oldfd, 0)
+            os.close(oldfd)
+            sys.stdin = oldsys 
         return outfile, errfile 
 
 class StdCapture(Capture):
-    """ capture sys.stdout/sys.stderr (but not system level fd 1 and 2).
-
-    This class allows to capture writes to sys.stdout|stderr "in-memory"
-    and will raise errors on tries to read from sys.stdin. 
+    """ This class allows to capture writes to sys.stdout|stderr "in-memory"
+        and will raise errors on tries to read from sys.stdin. It only
+        modifies sys.stdout|stderr|stdin attributes and does not 
+        touch underlying File Descriptors (use StdCaptureFD for that). 
     """
-    def __init__(self, out=True, err=True, mixed=False):
+    def __init__(self, out=True, err=True, in_=True, mixed=False):
         self._out = out
         self._err = err 
+        self._in = in_
         if out: 
             self.oldout = sys.stdout
             sys.stdout = self.newout = StringIO()
@@ -78,8 +90,9 @@ class StdCapture(Capture):
             else:
                 newerr = StringIO()
             sys.stderr = self.newerr = newerr
-        self.oldin  = sys.stdin
-        sys.stdin  = self.newin  = DontReadFromInput()
+        if in_:
+            self.oldin  = sys.stdin
+            sys.stdin  = self.newin  = DontReadFromInput()
 
     def reset(self):
         """ return captured output as strings and restore sys.stdout/err."""
@@ -106,7 +119,8 @@ class StdCapture(Capture):
             del self.olderr 
             errfile = self.newerr 
             errfile.seek(0)
-        sys.stdin = self.oldin 
+        if self._in:
+            sys.stdin = self.oldin 
         return outfile, errfile
 
 class DontReadFromInput:
@@ -121,3 +135,14 @@ class DontReadFromInput:
     readline = read
     readlines = read
     __iter__ = read
+
+try:
+    devnullpath = os.devnull
+except AttributeError:
+    if os.name == 'nt':
+        devnullpath = 'NUL'
+    else:
+        devnullpath = '/dev/null'
+
+emptyfile = StringIO()
+

py/io/test/test_stdcapture.py

@@ -79,6 +79,22 @@ class TestStdCapture:
         assert err == "world\n"
         assert not out 
 
+    def test_stdin_restored(self):
+        old = sys.stdin 
+        cap = self.getcapture(in_=True)
+        newstdin = sys.stdin 
+        out, err = cap.reset()
+        assert newstdin != sys.stdin
+        assert sys.stdin is old 
+
+    def test_stdin_nulled_by_default(self):
+        print "XXX this test may well hang instead of crashing"
+        print "XXX which indicates an error in the underlying capturing"
+        print "XXX mechanisms" 
+        cap = self.getcapture()
+        py.test.raises(IOError, "sys.stdin.read()")
+        out, err = cap.reset()
+
 class TestStdCaptureFD(TestStdCapture): 
     def getcapture(self, **kw): 
         return py.io.StdCaptureFD(**kw)