capture: ensure name of EncodedFile being a string

Fixes #2555.

Author: blueyed

_pytest/capture.py

@@ -252,6 +252,8 @@ def writelines(self, linelist):
         self.write(data)
 
     def __getattr__(self, name):
+        if name == 'name':
+            return '{!r}'.format(self.buffer)
         return getattr(object.__getattribute__(self, "buffer"), name)
 
 

testing/test_capture.py

@@ -715,25 +715,35 @@ def test_dupfile(tmpfile):
         assert nf not in flist
         print(i, end="", file=nf)
         flist.append(nf)
+
+    fname_open = flist[0].name
+    assert fname_open == repr(flist[0].buffer)
+
     for i in range(5):
         f = flist[i]
         f.close()
+    fname_closed = flist[0].name
+    assert fname_closed == repr(flist[0].buffer)
+    assert fname_closed != fname_open
     tmpfile.seek(0)
     s = tmpfile.read()
     assert "01234" in repr(s)
     tmpfile.close()
+    assert fname_closed == repr(flist[0].buffer)
 
 def test_dupfile_on_bytesio():
     io = py.io.BytesIO()
     f = capture.safe_text_dupfile(io, "wb")
     f.write("hello")
     assert io.getvalue() == b"hello"
+    assert f.name.startswith('<_io.BytesIO object at')
 
 def test_dupfile_on_textio():
     io = py.io.TextIO()
     f = capture.safe_text_dupfile(io, "wb")
     f.write("hello")
     assert io.getvalue() == "hello"
+    assert not hasattr(f, 'name')
 
 
 @contextlib.contextmanager