Only implement the extra space where it's required, fitting the spec more minimally.

Author: jaraco

importlib_metadata/__init__.py

@@ -696,16 +696,25 @@ def _convert_egg_info_reqs_to_simple_reqs(sections):
         def make_condition(name):
             return name and f'extra == "{name}"'
 
-        def parse_condition(section):
+        def quoted_marker(section):
             section = section or ''
             extra, sep, markers = section.partition(':')
             if extra and markers:
                 markers = f'({markers})'
             conditions = list(filter(None, [markers, make_condition(extra)]))
-            return ' ; ' + ' and '.join(conditions) if conditions else ''
+            return '; ' + ' and '.join(conditions) if conditions else ''
+
+        def url_req_space(req):
+            """
+            PEP 508 requires a space between the url_spec and the quoted_marker.
+            Ref python/importlib_metadata#357.
+            """
+            # '@' is uniquely indicative of a url_req.
+            return ' ' * ('@' in req)
 
         for section in sections:
-            yield section.value + parse_condition(section.name)
+            space = url_req_space(section.value)
+            yield section.value + space + quoted_marker(section.name)
 
 
 class DistributionFinder(MetaPathFinder):

tests/test_api.py

@@ -245,20 +245,20 @@ def test_more_complex_deps_requires_text(self):
 
             [extra1]
             dep4
-            dep5@ git+https://example.com/python/[email protected]
+            dep6@ git+https://example.com/python/[email protected]
 
             [extra2:python_version < "3"]
-            dep6
+            dep5
             """
         )
         deps = sorted(Distribution._deps_from_requires_text(requires))
         expected = [
             'dep1',
             'dep2',
-            'dep3 ; python_version < "3"',
-            'dep4 ; extra == "extra1"',
-            'dep5@ git+https://example.com/python/[email protected] ; extra == "extra1"',
-            'dep6 ; (python_version < "3") and extra == "extra2"',
+            'dep3; python_version < "3"',
+            'dep4; extra == "extra1"',
+            'dep5; (python_version < "3") and extra == "extra2"',
+            'dep6@ git+https://example.com/python/[email protected] ; extra == "extra1"',
         ]
         # It's important that the environment marker expression be
         # wrapped in parentheses to avoid the following 'and' binding more