Merge pull request #3315 from pytest-dev/issue/3314

Allow DontReadFromInput to produce iterator without error.

_pytest/capture.py

@@ -560,7 +560,7 @@ class SysCaptureBinary(SysCapture):
         return res
 
 
-class DontReadFromInput(object):
+class DontReadFromInput(six.Iterator):
     """Temporary stub class.  Ideally when stdin is accessed, the
     capturing should be turned off, with possibly all data captured
     so far sent to the screen.  This should be configurable, though,
@@ -574,7 +574,10 @@ class DontReadFromInput(object):
         raise IOError("reading from stdin while output is captured")
     readline = read
     readlines = read
-    __iter__ = read
+    __next__ = read
+
+    def __iter__(self):
+        return self
 
     def fileno(self):
         raise UnsupportedOperation("redirected stdin is pseudofile, "

changelog/3314.bugfix.rst

@@ -0,0 +1,3 @@
+During test collection, when stdin is not allowed to be read, the
+``DontReadFromStdin`` object still allow itself to be iterable and
+resolved to an iterator without crashing.

testing/test_capture.py

@@ -751,7 +751,8 @@ def test_dontreadfrominput():
     assert not f.isatty()
     pytest.raises(IOError, f.read)
     pytest.raises(IOError, f.readlines)
-    pytest.raises(IOError, iter, f)
+    iter_f = iter(f)
+    pytest.raises(IOError, next, iter_f)
     pytest.raises(UnsupportedOperation, f.fileno)
     f.close()  # just for completeness
 
@@ -764,7 +765,8 @@ def test_dontreadfrominput_buffer_python3():
     assert not fb.isatty()
     pytest.raises(IOError, fb.read)
     pytest.raises(IOError, fb.readlines)
-    pytest.raises(IOError, iter, fb)
+    iter_f = iter(f)
+    pytest.raises(IOError, next, iter_f)
     pytest.raises(ValueError, fb.fileno)
     f.close()  # just for completeness