From 196706d305c1e7cb296824c90d932918036f53e2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C3=A9phane=20Bidoul?= <stephane.bidoul@gmail.com>
Date: Sat, 1 Feb 2020 13:40:35 +0100
Subject: [PATCH] Better freeze using direct_url.json

---
 news/609.feature                       |  2 ++
 src/pip/_internal/operations/freeze.py | 16 ++++++++++++++++
 tests/functional/test_freeze.py        |  8 ++++++++
 3 files changed, 26 insertions(+)
 create mode 100644 news/609.feature

diff --git a/news/609.feature b/news/609.feature
new file mode 100644
index 00000000000..1a2a6702a58
--- /dev/null
+++ b/news/609.feature
@@ -0,0 +1,2 @@
+pip now implements PEP 610, so ``pip freeze`` has better fidelity
+in presence of distributions installed from Direct URL requirements.
diff --git a/src/pip/_internal/operations/freeze.py b/src/pip/_internal/operations/freeze.py
index 0ac3c4e9028..3198c775771 100644
--- a/src/pip/_internal/operations/freeze.py
+++ b/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,
@@ -250,8 +254,20 @@ 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
+        #      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)
diff --git a/tests/functional/test_freeze.py b/tests/functional/test_freeze.py
index dabfbde483c..7027879bd44 100644
--- a/tests/functional/test_freeze.py
+++ b/tests/functional/test_freeze.py
@@ -816,3 +816,11 @@ def test_freeze_path_multiple(tmpdir, script, data):
         simple2==3.0
         <BLANKLINE>""")
     _check_output(result.stdout, expected)
+
+
+def test_freeze_direct_url_archive(script, shared_data, with_wheel):
+    req = "simple @ " + path_to_url(shared_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