Better freeze using direct_url.json

Author: sbidoul

news/609.feature

@@ -0,0 +1,2 @@
+Pip freeze now implements PEP 610, so ``pip freeze`` has now better fidelity
+in presence of distributions installed from Direct URL requirements.

src/pip/_internal/operations/freeze.py

@@ -19,6 +19,10 @@
     install_req_from_line,
 )
 from pip._internal.req.req_file import COMMENT_RE
+from pip._internal.utils.direct_url_helpers import (
+    direct_url_as_pep440_direct_reference,
+    dist_get_direct_url,
+)
 from pip._internal.utils.misc import (
     dist_is_editable,
     get_installed_distributions,
@@ -252,8 +256,20 @@ def __init__(self, name, req, editable, comments=()):
     @classmethod
     def from_dist(cls, dist):
         # type: (Distribution) -> FrozenRequirement
+        # TODO `get_requirement_info` is taking care of editable requirements.
+        # TODO This should be refactored when we will add detection of
+        # TODO editable that provide .dist-info metadata.
         req, editable, comments = get_requirement_info(dist)
+        if req is None and not editable:
+            # if PEP 610 metadata is present, attempt to use it
+            direct_url = dist_get_direct_url(dist)
+            if direct_url:
+                req = direct_url_as_pep440_direct_reference(
+                    direct_url, dist.project_name
+                )
+                comments = []
         if req is None:
+            # name==version requirement
             req = dist.as_requirement()
 
         return cls(dist.project_name, req, editable, comments=comments)

tests/functional/test_freeze.py

@@ -782,3 +782,11 @@ def test_freeze_path_multiple(tmpdir, script, data):
         simple2==3.0
         <BLANKLINE>""")
     _check_output(result.stdout, expected)
+
+
+def test_freeze_direct_url_archive(script, data, with_wheel):
+    req = "simple @ " + path_to_url(data.packages / "simple-2.0.tar.gz")
+    assert req.startswith("simple @ file://")
+    script.pip("install", req)
+    result = script.pip("freeze")
+    assert req in result.stdout