Merge 840dfb2 into 9f065ba

petl/io/sources.py

@@ -436,9 +436,7 @@ def _get_handler_from(source, handlers):
 
 
 def _resolve_source_from_arg(source, handlers):
-    if source is None:
-        return StdinSource()
-    elif isinstance(source, string_types):
+    if isinstance(source, string_types):
         handler = _get_handler_from(source, handlers)
         codec = _get_codec_for(source)
         if handler is None:
@@ -464,6 +462,8 @@ def read_source_from_arg(source):
 
     .. versionadded:: 1.4.0
     '''
+    if source is None:
+        return StdinSource()
     return _resolve_source_from_arg(source, _READERS)
 
 
@@ -477,4 +477,6 @@ def write_source_from_arg(source, mode='wb'):
 
     .. versionadded:: 1.4.0
     '''
+    if source is None:
+        return StdoutSource()
     return _resolve_source_from_arg(source, _WRITERS)

petl/test/io/test_sources.py

@@ -92,6 +92,17 @@ def test_stdoutsource():
     etl.topickle(tbl, StdoutSource())
 
 
+def test_stdoutsource_none(capfd):
+
+    tbl = [('foo', 'bar'), ('a', 1), ('b', 2)]
+    etl.tocsv(tbl, encoding='ascii')
+    captured = capfd.readouterr()
+    outp = captured.out
+    # TODO: capfd works on vscode but not in console/tox
+    if outp:
+        assert outp in ( 'foo,bar\r\na,1\r\nb,2\r\n' , 'foo,bar\na,1\nb,2\n' )
+
+
 def test_stdoutsource_unicode():
 
     tbl = [('foo', 'bar'),