stubgen: Handle commas in namedtuple field definition (#10828)

Author: ismeta

mypy/stubgen.py

@@ -926,7 +926,7 @@ def process_namedtuple(self, lvalue: NameExpr, rvalue: CallExpr) -> None:
         if self._state != EMPTY:
             self.add('\n')
         if isinstance(rvalue.args[1], StrExpr):
-            items = rvalue.args[1].value.split(" ")
+            items = rvalue.args[1].value.replace(',', ' ').split()
         elif isinstance(rvalue.args[1], (ListExpr, TupleExpr)):
             list_items = cast(List[StrExpr], rvalue.args[1].items)
             items = [item.value for item in list_items]

test-data/unit/stubgen.test

@@ -590,6 +590,28 @@ xx
 [out]
 from typing import Any, NamedTuple
 
+class X(NamedTuple):
+    a: Any
+    b: Any
+
+[case testNamedtupleAltSyntaxUsingComma]
+from collections import namedtuple, xx
+X = namedtuple('X', 'a,    b')
+xx
+[out]
+from typing import Any, NamedTuple
+
+class X(NamedTuple):
+    a: Any
+    b: Any
+
+[case testNamedtupleAltSyntaxUsingMultipleCommas]
+from collections import namedtuple, xx
+X = namedtuple('X', 'a,,   b')
+xx
+[out]
+from typing import Any, NamedTuple
+
 class X(NamedTuple):
     a: Any
     b: Any