Allow PEP 508 URL spec as editable

news/1289.feature.rst

@@ -0,0 +1 @@
+Add support to install a PEP 508 URL-specified requirement as editable.

src/pip/_internal/req/constructors.py

@@ -71,11 +71,24 @@ def parse_editable(editable_req):
         - a requirement name
         - an URL
         - extras
-        - editable options
     Accepted requirements:
-        svn+http://blahblah@rev#egg=Foobar[baz]&subdirectory=version_subdir
-        .[some_extra]
+        - svn+http://blahblah@rev#egg=Foobar[baz]&subdirectory=version_subdir
+        - local_path[some_extra]
+        - Foobar[extra] @ svn+http://blahblah@rev#subdirectory=subdir ; markers
     """
+    try:
+        req = Requirement(editable_req)
+    except InvalidRequirement:
+        pass
+    else:
+        if req.url:
+            # Join the marker back into the name part. This will be parsed out
+            # later into a Requirement again.
+            if req.marker:
+                name = f"{req.name} ; {req.marker}"
+            else:
+                name = req.name
+            return (name, req.url, req.extras)
 
     url = editable_req
 

tests/unit/test_req.py

@@ -606,6 +606,23 @@ def test_parse_editable_vcs_extras():
     )
 
 
+@pytest.mark.parametrize(
+    "req_str, expected",
+    [
+        (
+            'foo[extra] @ svn+http://foo ; os_name == "nt"',
+            ('foo ; os_name == "nt"', 'svn+http://foo', {'extra'}),
+        ),
+        (
+            'foo @ svn+http://foo',
+            ('foo', 'svn+http://foo', set()),
+        ),
+    ],
+)
+def test_parse_editable_pep508(req_str, expected):
+    assert parse_editable(req_str) == expected
+
+
 @patch('pip._internal.req.req_install.os.path.abspath')
 @patch('pip._internal.req.req_install.os.path.exists')
 @patch('pip._internal.req.req_install.os.path.isdir')