simplify reset/stop_capturing and fix capturing wrt to capturing simple os.write() calls

_pytest/capture.py

@@ -6,7 +6,7 @@ from __future__ import with_statement
 
 import sys
 import os
-import tempfile
+from tempfile import TemporaryFile
 import contextlib
 
 import py
@@ -101,12 +101,6 @@ def pytest_load_initial_conftests(early_config, parser, args, __multicall__):
 
 
 
-def maketmpfile():
-    f = py.std.tempfile.TemporaryFile()
-    newf = dupfile(f, encoding="UTF-8")
-    f.close()
-    return newf
-
 class CaptureManager:
     def __init__(self, defaultmethod=None):
         self._method2capture = {}
@@ -137,7 +131,7 @@ class CaptureManager:
     def reset_capturings(self):
         for cap in self._method2capture.values():
             cap.pop_outerr_to_orig()
-            cap.reset()
+            cap.stop_capturing()
         self._method2capture.clear()
 
     def resumecapture_item(self, item):
@@ -274,15 +268,16 @@ def pytest_funcarg__capfd(request):
 
 class CaptureFixture:
     def __init__(self, captureclass):
-        self._capture = StdCaptureBase(out=True, err=True, in_=False,
+        self.captureclass = captureclass
-                                   Capture=captureclass)
 
     def _start(self):
+        self._capture = StdCaptureBase(out=True, err=True, in_=False,
+                                       Capture=self.captureclass)
         self._capture.start_capturing()
 
     def _finalize(self):
         if hasattr(self, '_capture'):
-            outerr = self._outerr = self._capture.reset()
+            outerr = self._outerr = self._capture.stop_capturing()
             del self._capture
             return outerr
 
@@ -355,21 +350,6 @@ class StdCaptureBase(object):
         if err:
             self.err = Capture(2)
 
-    def reset(self):
-        """ reset sys.stdout/stderr and return captured output as strings. """
-        if hasattr(self, '_reset'):
-            raise ValueError("was already reset")
-        self._reset = True
-        outfile, errfile = self.stop_capturing()
-        out, err = "", ""
-        if outfile and not outfile.closed:
-            out = outfile.read()
-            outfile.close()
-        if errfile and errfile != outfile and not errfile.closed:
-            err = errfile.read()
-            errfile.close()
-        return out, err
-
     def start_capturing(self):
         if self.in_:
             self.in_.start()
@@ -378,17 +358,6 @@ class StdCaptureBase(object):
         if self.err:
             self.err.start()
 
-    def stop_capturing(self):
-        """ return (outfile, errfile) and stop capturing. """
-        outfile = errfile = None
-        if self.out:
-            outfile = self.out.done()
-        if self.err:
-            errfile = self.err.done()
-        if self.in_:
-            self.in_.done()
-        return outfile, errfile
-
     def pop_outerr_to_orig(self):
         """ pop current snapshot out/err capture and flush to orig streams. """
         out, err = self.readouterr()
@@ -397,25 +366,27 @@ class StdCaptureBase(object):
         if err:
             self.err.writeorg(err)
 
+    def stop_capturing(self):
+        """ stop capturing and reset capturing streams """
+        if hasattr(self, '_reset'):
+            raise ValueError("was already stopped")
+        self._reset = True
+        if self.out:
+            self.out.done()
+        if self.err:
+            self.err.done()
+        if self.in_:
+            self.in_.done()
+
     def readouterr(self):
         """ return snapshot unicode value of stdout/stderr capturings. """
         return self._readsnapshot('out'), self._readsnapshot('err')
 
     def _readsnapshot(self, name):
-        try:
+        cap = getattr(self, name, None)
-            f = getattr(self, name).tmpfile
+        if cap is None:
-        except AttributeError:
+            return ""
-            return ''
+        return cap.snap()
-        if f.tell() == 0:
-            return ''
-        f.seek(0)
-        res = f.read()
-        enc = getattr(f, "encoding", None)
-        if enc and isinstance(res, bytes):
-            res = py.builtin._totext(res, enc, "replace")
-        f.truncate(0)
-        f.seek(0)
-        return res
 
 
 class FDCapture:
@@ -433,11 +404,16 @@ class FDCapture:
                 if targetfd == 0:
                     tmpfile = open(os.devnull, "r")
                 else:
-                    tmpfile = maketmpfile()
+                    f = TemporaryFile()
+                    with f:
+                        tmpfile = dupfile(f, encoding="UTF-8")
             self.tmpfile = tmpfile
             if targetfd in patchsysdict:
                 self._oldsys = getattr(sys, patchsysdict[targetfd])
 
+    def __repr__(self):
+        return "<FDCapture %s oldfd=%s>" % (self.targetfd, self._savefd)
+
     def start(self):
         """ Start capturing on targetfd using memorized tmpfile. """
         try:
@@ -450,16 +426,26 @@ class FDCapture:
             subst = self.tmpfile if targetfd != 0 else DontReadFromInput()
             setattr(sys, patchsysdict[targetfd], subst)
 
+    def snap(self):
+        f = self.tmpfile
+        f.seek(0)
+        res = f.read()
+        if res:
+            enc = getattr(f, "encoding", None)
+            if enc and isinstance(res, bytes):
+                res = py.builtin._totext(res, enc, "replace")
+            f.truncate(0)
+            f.seek(0)
+        return res
+
     def done(self):
         """ stop capturing, restore streams, return original capture file,
         seeked to position zero. """
         os.dup2(self._savefd, self.targetfd)
         os.close(self._savefd)
-        if self.targetfd != 0:
-            self.tmpfile.seek(0)
         if hasattr(self, '_oldsys'):
             setattr(sys, patchsysdict[self.targetfd], self._oldsys)
-        return self.tmpfile
+        self.tmpfile.close()
 
     def writeorg(self, data):
         """ write a string to the original file descriptor
@@ -482,18 +468,22 @@ class SysCapture:
     def start(self):
         setattr(sys, self.name, self.tmpfile)
 
+    def snap(self):
+        f = self.tmpfile
+        res = f.getvalue()
+        f.truncate(0)
+        f.seek(0)
+        return res
+
     def done(self):
         setattr(sys, self.name, self._old)
-        if self.name != "stdin":
+        self.tmpfile.close()
-            self.tmpfile.seek(0)
-        return self.tmpfile
 
     def writeorg(self, data):
         self._old.write(data)
         self._old.flush()
 
 
-
 class DontReadFromInput:
     """Temporary stub class.  Ideally when stdin is accessed, the
     capturing should be turned off, with possibly all data captured

testing/test_capture.py

@@ -103,7 +103,7 @@ class TestCaptureManager:
             assert not out and not err
             capman.reset_capturings()
         finally:
-            capouter.reset()
+            capouter.stop_capturing()
 
     @needsosdup
     def test_juggle_capturings(self, testdir):
@@ -127,7 +127,7 @@ class TestCaptureManager:
             finally:
                 capman.reset_capturings()
         finally:
-            capouter.reset()
+            capouter.stop_capturing()
 
 
 @pytest.mark.parametrize("method", ['fd', 'sys'])
@@ -696,17 +696,15 @@ class TestFDCapture:
         cap = capture.FDCapture(fd)
         data = tobytes("hello")
         os.write(fd, data)
-        f = cap.done()
+        s = cap.snap()
-        s = f.read()
+        cap.done()
-        f.close()
         assert not s
         cap = capture.FDCapture(fd)
         cap.start()
         os.write(fd, data)
-        f = cap.done()
+        s = cap.snap()
-        s = f.read()
+        cap.done()
         assert s == "hello"
-        f.close()
 
     def test_simple_many(self, tmpfile):
         for i in range(10):
@@ -720,16 +718,15 @@ class TestFDCapture:
     def test_simple_fail_second_start(self, tmpfile):
         fd = tmpfile.fileno()
         cap = capture.FDCapture(fd)
-        f = cap.done()
+        cap.done()
         pytest.raises(ValueError, cap.start)
-        f.close()
 
     def test_stderr(self):
         cap = capture.FDCapture(2)
         cap.start()
         print_("hello", file=sys.stderr)
-        f = cap.done()
+        s = cap.snap()
-        s = f.read()
+        cap.done()
         assert s == "hello\n"
 
     def test_stdin(self, tmpfile):
@@ -752,8 +749,8 @@ class TestFDCapture:
             cap.writeorg(data2)
         finally:
             tmpfile.close()
-        f = cap.done()
+        scap = cap.snap()
-        scap = f.read()
+        cap.done()
         assert scap == totext(data1)
         stmp = open(tmpfile.name, 'rb').read()
         assert stmp == data2
@@ -769,17 +766,17 @@ class TestStdCapture:
         cap = self.getcapture()
         sys.stdout.write("hello")
         sys.stderr.write("world")
-        outfile, errfile = cap.stop_capturing()
+        out, err = cap.readouterr()
-        s = outfile.read()
+        cap.stop_capturing()
-        assert s == "hello"
+        assert out == "hello"
-        s = errfile.read()
+        assert err == "world"
-        assert s == "world"
 
     def test_capturing_reset_simple(self):
         cap = self.getcapture()
         print("hello world")
         sys.stderr.write("hello error\n")
-        out, err = cap.reset()
+        out, err = cap.readouterr()
+        cap.stop_capturing()
         assert out == "hello world\n"
         assert err == "hello error\n"
 
@@ -792,8 +789,9 @@ class TestStdCapture:
             assert out == "hello world\n"
             assert err == "hello error\n"
             sys.stderr.write("error2")
+            out, err = cap.readouterr()
         finally:
-            out, err = cap.reset()
+            cap.stop_capturing()
         assert err == "error2"
 
     def test_capturing_readouterr_unicode(self):
@@ -802,7 +800,7 @@ class TestStdCapture:
             print ("hx\xc4\x85\xc4\x87")
             out, err = cap.readouterr()
         finally:
-            cap.reset()
+            cap.stop_capturing()
         assert out == py.builtin._totext("hx\xc4\x85\xc4\x87\n", "utf8")
 
     @pytest.mark.skipif('sys.version_info >= (3,)',
@@ -813,13 +811,14 @@ class TestStdCapture:
         print('\xa6')
         out, err = cap.readouterr()
         assert out == py.builtin._totext('\ufffd\n', 'unicode-escape')
-        cap.reset()
+        cap.stop_capturing()
 
     def test_reset_twice_error(self):
         cap = self.getcapture()
         print ("hello")
-        out, err = cap.reset()
+        out, err = cap.readouterr()
-        pytest.raises(ValueError, cap.reset)
+        cap.stop_capturing()
+        pytest.raises(ValueError, cap.stop_capturing)
         assert out == "hello\n"
         assert not err
 
@@ -833,7 +832,8 @@ class TestStdCapture:
         sys.stderr = capture.TextIO()
         print ("not seen")
         sys.stderr.write("not seen\n")
-        out, err = cap.reset()
+        out, err = cap.readouterr()
+        cap.stop_capturing()
         assert out == "hello"
         assert err == "world"
         assert sys.stdout == oldout
@@ -844,8 +844,10 @@ class TestStdCapture:
         print ("cap1")
         cap2 = self.getcapture()
         print ("cap2")
-        out2, err2 = cap2.reset()
+        out2, err2 = cap2.readouterr()
-        out1, err1 = cap1.reset()
+        out1, err1 = cap1.readouterr()
+        cap2.stop_capturing()
+        cap1.stop_capturing()
         assert out1 == "cap1\n"
         assert out2 == "cap2\n"
 
@@ -853,7 +855,8 @@ class TestStdCapture:
         cap = self.getcapture(out=True, err=False)
         sys.stdout.write("hello")
         sys.stderr.write("world")
-        out, err = cap.reset()
+        out, err = cap.readouterr()
+        cap.stop_capturing()
         assert out == "hello"
         assert not err
 
@@ -861,7 +864,8 @@ class TestStdCapture:
         cap = self.getcapture(out=False, err=True)
         sys.stdout.write("hello")
         sys.stderr.write("world")
-        out, err = cap.reset()
+        out, err = cap.readouterr()
+        cap.stop_capturing()
         assert err == "world"
         assert not out
 
@@ -869,7 +873,7 @@ class TestStdCapture:
         old = sys.stdin
         cap = self.getcapture(in_=True)
         newstdin = sys.stdin
-        out, err = cap.reset()
+        cap.stop_capturing()
         assert newstdin != sys.stdin
         assert sys.stdin is old
 
@@ -879,7 +883,7 @@ class TestStdCapture:
         print ("XXX mechanisms")
         cap = self.getcapture()
         pytest.raises(IOError, "sys.stdin.read()")
-        out, err = cap.reset()
+        cap.stop_capturing()
 
 
 class TestStdCaptureFD(TestStdCapture):
@@ -890,6 +894,20 @@ class TestStdCaptureFD(TestStdCapture):
         cap.start_capturing()
         return cap
 
+    def test_simple_only_fd(self, testdir):
+        testdir.makepyfile("""
+            import os
+            def test_x():
+                os.write(1, "hello\\n".encode("ascii"))
+                assert 0
+        """)
+        result = testdir.runpytest()
+        result.stdout.fnmatch_lines("""
+            *test_x*
+            *assert 0*
+            *Captured stdout*
+        """)
+
     def test_intermingling(self):
         cap = self.getcapture()
         oswritebytes(1, "1")
@@ -900,7 +918,8 @@ class TestStdCaptureFD(TestStdCapture):
         sys.stderr.write("b")
         sys.stderr.flush()
         oswritebytes(2, "c")
-        out, err = cap.reset()
+        out, err = cap.readouterr()
+        cap.stop_capturing()
         assert out == "123"
         assert err == "abc"
 
@@ -908,7 +927,7 @@ class TestStdCaptureFD(TestStdCapture):
         with lsof_check():
             for i in range(10):
                 cap = StdCaptureFD()
-                cap.reset()
+                cap.stop_capturing()
 
 
 
@@ -943,10 +962,6 @@ class TestStdCaptureFDinvalidFD:
 def test_capture_not_started_but_reset():
     capsys = StdCapture()
     capsys.stop_capturing()
-    capsys.stop_capturing()
-    capsys.reset()
-
-
 
 
 @needsosdup
@@ -960,7 +975,7 @@ def test_fdcapture_tmpfile_remains_the_same(tmpfile, use):
         capfile = cap.err.tmpfile
         cap.readouterr()
     finally:
-        cap.reset()
+        cap.stop_capturing()
     capfile2 = cap.err.tmpfile
     assert capfile2 == capfile