Add more tests to cover different iterables

Author: agriyakhetarpal

distutils/tests/test_extension.py

@@ -69,7 +69,7 @@ def test_extension_init(self):
         assert ext.name == 'name'
 
         # the second argument, which is the list of files, must
-        # be a list of strings or PathLike objects
+        # be a list of strings or PathLike objects, and not a string
         with pytest.raises(AssertionError):
             Extension('name', 'file')
         with pytest.raises(AssertionError):
@@ -79,6 +79,16 @@ def test_extension_init(self):
         ext = Extension('name', [pathlib.Path('file1'), pathlib.Path('file2')])
         assert ext.sources == ['file1', 'file2']
 
+        # any non-string iterable of strings or PathLike objects should work
+        ext = Extension('name', ('file1', 'file2'))  # tuple
+        assert ext.sources == ['file1', 'file2']
+        ext = Extension('name', {'file1', 'file2'})  # set
+        assert sorted(ext.sources) == ['file1', 'file2']
+        ext = Extension('name', iter(['file1', 'file2']))  # iterator
+        assert ext.sources == ['file1', 'file2']
+        ext = Extension('name', [pathlib.Path('file1'), 'file2'])  # mixed types
+        assert ext.sources == ['file1', 'file2']
+
         # others arguments have defaults
         for attr in (
             'include_dirs',