Move InstallationCandidate to pip.index

Move InstallationCandidate from `pip.req.req_requirement` to
`pip.index`, the one place where it's used.

pip/index.py

@@ -28,7 +28,6 @@ from pip.download import url_to_path, path_to_url
 from pip.models import PyPI
 from pip.wheel import Wheel, wheel_ext
 from pip.pep425tags import supported_tags, supported_tags_noarch, get_platform
-from pip.req.req_requirement import InstallationCandidate
 from pip._vendor import html5lib, requests, pkg_resources, six
 from pip._vendor.packaging.version import parse as parse_version
 from pip._vendor.requests.exceptions import SSLError
@@ -51,6 +50,48 @@ SECURE_ORIGINS = [
 logger = logging.getLogger(__name__)
 
 
+class InstallationCandidate(object):
+
+    def __init__(self, project, version, location):
+        self.project = project
+        self.version = parse_version(version)
+        self.location = location
+        self._key = (self.project, self.version, self.location)
+
+    def __repr__(self):
+        return "<InstallationCandidate({0!r}, {1!r}, {2!r})>".format(
+            self.project, self.version, self.location,
+        )
+
+    def __hash__(self):
+        return hash(self._key)
+
+    def __lt__(self, other):
+
+        return self._compare(other, lambda s, o: s < o)
+
+    def __le__(self, other):
+        return self._compare(other, lambda s, o: s <= o)
+
+    def __eq__(self, other):
+        return self._compare(other, lambda s, o: s == o)
+
+    def __ge__(self, other):
+        return self._compare(other, lambda s, o: s >= o)
+
+    def __gt__(self, other):
+        return self._compare(other, lambda s, o: s > o)
+
+    def __ne__(self, other):
+        return self._compare(other, lambda s, o: s != o)
+
+    def _compare(self, other, method):
+        if not isinstance(other, InstallationCandidate):
+            return NotImplemented
+
+        return method(self._key, other._key)
+
+
 class PackageFinder(object):
     """This finds packages.
 

pip/req/req_requirement.py

@@ -1,43 +0,0 @@
-from pip._vendor.packaging.version import parse as parse_version
-
-
-class InstallationCandidate(object):
-
-    def __init__(self, project, version, location):
-        self.project = project
-        self.version = parse_version(version)
-        self.location = location
-        self._key = (self.project, self.version, self.location)
-
-    def __repr__(self):
-        return "<InstallationCandidate({0!r}, {1!r}, {2!r})>".format(
-            self.project, self.version, self.location,
-        )
-
-    def __hash__(self):
-        return hash(self._key)
-
-    def __lt__(self, other):
-
-        return self._compare(other, lambda s, o: s < o)
-
-    def __le__(self, other):
-        return self._compare(other, lambda s, o: s <= o)
-
-    def __eq__(self, other):
-        return self._compare(other, lambda s, o: s == o)
-
-    def __ge__(self, other):
-        return self._compare(other, lambda s, o: s >= o)
-
-    def __gt__(self, other):
-        return self._compare(other, lambda s, o: s > o)
-
-    def __ne__(self, other):
-        return self._compare(other, lambda s, o: s != o)
-
-    def _compare(self, other, method):
-        if not isinstance(other, InstallationCandidate):
-            return NotImplemented
-
-        return method(self._key, other._key)

tests/unit/test_finder.py

@@ -5,13 +5,12 @@ import pip.pep425tags
 
 from pkg_resources import parse_version, Distribution
 from pip.req import InstallRequirement
-from pip.index import PackageFinder, Link
+from pip.index import InstallationCandidate, PackageFinder, Link
 from pip.exceptions import (
     BestVersionAlreadyInstalled, DistributionNotFound, InstallationError,
 )
 from pip.utils import Inf
 from pip.download import PipSession
-from pip.req.req_requirement import InstallationCandidate
 
 from mock import Mock, patch