Add test

Signed-off-by: Dan Ryan <dan@danryan.co>

tests/integration/test_lock.py

@@ -1,5 +1,6 @@
 import pytest
 import os
+import sys
 
 from pipenv.utils import temp_environ
 
@@ -517,3 +518,25 @@ def test_lock_no_warnings(PipenvInstance, pypi):
         assert "Warning" in c.err
         assert "Warning" not in c.out
         assert "hello" in c.out
+
+
+@pytest.mark.lock
+@pytest.mark.install
+@pytest.mark.skipif(sys.version_info >= (3, 5), reason="scandir doesn't get installed on python 3.5+")
+def test_lock_missing_cache_entries_gets_all_hashes(monkeypatch, PipenvInstance, pypi, tmpdir):
+    """
+    Test locking pathlib2 on python2.7 which needs `scandir`, but fails to resolve when
+    using a fresh dependency cache.
+    """
+
+    with monkeypatch.context() as m:
+        monkeypatch.setattr("pipenv.patched.piptools.locations.CACHE_DIR", tmpdir.strpath)
+        with PipenvInstance(pypi=pypi, chdir=True) as p:
+            p._pipfile.add("pathlib2", "*")
+            assert "pathlib2" in p.pipfile["packages"]
+            c = p.pipenv("install")
+            assert c.return_code == 0, c.err
+            assert "pathlib2" in p.lockfile["default"]
+            assert "scandir" in p.lockfile["default"]
+            assert isinstance(p.lockfile["default"]["scandir"]["hashes"], list)
+            assert len(p.lockfile["default"]["scandir"]["hashes"]) > 1