Simplify/improve Package.clone() (#159)

Downstream clients (e.g., poetry) appear to assume that the result
of a Package.clone() will be a full-fidelity copy of the original.

Use `copy.deepcopy` to clone the object, and ensure that this is
the case.

Resolves Issue #2422

Co-authored-by: Nicolas Simonds <nisimond@cisco.com>

poetry/core/packages/package.py

@@ -428,33 +428,8 @@ def without_features(self) -> "Package":
         return self.with_features([])
 
     def clone(self) -> "Package":
-        if self.is_root():
-            clone = self.__class__(self.pretty_name, self.version)
-        else:
-            clone = self.__class__(
-                self.pretty_name,
-                self.version,
-                source_type=self._source_type,
-                source_url=self._source_url,
-                source_reference=self._source_reference,
-                features=list(self.features),
-            )
-
-        clone.description = self.description
-        clone.category = self.category
-        clone.optional = self.optional
-        clone.python_versions = self.python_versions
-        clone.marker = self.marker
-        clone.extras = self.extras
-        clone.root_dir = self.root_dir
-        clone.develop = self.develop
-
-        for dep in self.requires:
-            clone.requires.append(dep)
-
-        for dep in self.dev_requires:
-            clone.dev_requires.append(dep)
-
+        clone = self.__class__(self.pretty_name, self.version)
+        clone.__dict__ = copy.deepcopy(self.__dict__)
         return clone
 
     def __hash__(self) -> int:

tests/packages/test_package.py

@@ -1,5 +1,7 @@
 from __future__ import unicode_literals
 
+import random
+
 from pathlib import Path
 
 import pytest
@@ -280,3 +282,30 @@ def test_to_dependency_for_url():
     assert "https://example.com/path.tar.gz" == dep.url
     assert "url" == dep.source_type
     assert "https://example.com/path.tar.gz" == dep.source_url
+
+
+def test_package_clone(f):
+    # TODO(nic): this test is not future-proof, in that any attributes added
+    #  to the Package object and not filled out in this test setup might
+    #  cause comparisons to match that otherwise should not.  A factory method
+    #  to create a Package object with all fields fully randomized would be the
+    #  most rigorous test for this, but that's likely overkill.
+    p = Package(
+        "lol_wut",
+        "3.141.5926535",
+        pretty_version="③.⑭.⑮",
+        source_type="git",
+        source_url="http://some.url",
+        source_reference="fe4d2adabf3feb5d32b70ab5c105285fa713b10c",
+        source_resolved_reference="fe4d2adabf3feb5d32b70ab5c105285fa713b10c",
+        features=["abc", "def"],
+        develop=random.choice((True, False)),
+    )
+    p.files = (["file1", "file2", "file3"],)
+    p.homepage = "https://some.other.url"
+    p.repository_url = "http://bug.farm"
+    p.documentation_url = "http://lorem.ipsum/dolor/sit.amet"
+    p2 = p.clone()
+
+    assert p == p2
+    assert p.__dict__ == p2.__dict__