WheelFile: finish from_wheelfile

CHANGELOG.md

@@ -22,6 +22,9 @@ Versioning](https://semver.org/spec/v2.0.0.html).
   wheel name (`.build_tag`).
 
 ### Added
+- `WheelFile.from_wheelfile` - a constructor class-method that makes it
+  possible to recreate a wheel and: rename it (change distname, version,
+  buildnumber and/or tags), append files to it, change its metadata, etc.
 - `WheelFile.METADATA_FILENAMES` - a static field with a set of names of
   metadata files managed by this class.
 - `WheelFile.writestr_distinfo` - similar to `write_distinfo`, this is a safe

tests/test_wheelfile_cloning.py

@@ -418,11 +418,23 @@ def test_raises_VE_when_same_path_used(self, wf, buf, tmp_file):
             with pytest.raises(ValueError):
                 WheelFile.from_wheelfile(wf, tmp_file)
 
-    def test_raises_VE_when_same_path_used_relatively(self, wf, buf, tmp_path):
+    def test_raises_VE_when_same_path_used_relatively(self, wf, tmp_path):
         (tmp_path / 'relative/').mkdir()
         (tmp_path / 'path/').mkdir()
         path = (tmp_path / 'relative/../path/../')
         assert path.is_dir()
         with WheelFile(path, mode='w', distname='_', version='0') as wf:
             with pytest.raises(ValueError):
                 WheelFile.from_wheelfile(wf, tmp_path)
+
+    @pytest.fixture
+    def tmp_cwd(self, tmp_path):
+        old_dir = os.getcwd()
+        os.chdir(tmp_path)
+        yield tmp_path
+        os.chdir(old_dir)
+
+    def test_raises_VE_when_same_path_used_via_curdir(self, tmp_cwd):
+        with WheelFile(tmp_cwd, mode='w', distname='_', version='0') as wf:
+            with pytest.raises(ValueError):
+                WheelFile.from_wheelfile(wf)

wheelfile.py

@@ -1342,6 +1342,12 @@ def from_wheelfile(
         if platform_tag is cls._unspecified:
             platform_tag = wf.platform_tag
 
+        # Required for the path check below
+        if isinstance(version, str):
+            version = Version(version)
+        if isinstance(file_or_path, str):
+            file_or_path = Path(file_or_path)
+
         # For MyPy
         assert isinstance(distname, str) or distname is None
         assert isinstance(version, (str, Version)) or version is None
@@ -1356,6 +1362,36 @@ def from_wheelfile(
                 "same as the one used by the other WheelFile object."
             )
 
+        f_o_p = file_or_path  # For brevity
+        dir_path = (
+            f_o_p.resolve() if isinstance(f_o_p, Path) and f_o_p.is_dir() else
+            f_o_p.parent.resolve() if isinstance(f_o_p, Path) else
+            getattr(f_o_p, 'name', None)
+        )
+
+        # wf.zipfile.filename is not None only when it is writing to a file
+        both_are_files = (
+            wf.zipfile.filename is not None
+            and dir_path is not None
+        )
+
+        if both_are_files:
+            assert wf.zipfile.filename is not None  # For MyPy
+            # Ensure we won't overwrite wf
+            wf_dir_path = Path(wf.zipfile.filename).parent.resolve()
+            if wf_dir_path == dir_path and (
+                wf.distname == distname
+                and wf.version == version
+                and wf.build_tag == build_tag
+                and wf.language_tag == language_tag
+                and wf.abi_tag == abi_tag
+                and wf.platform_tag == platform_tag
+            ):
+                raise ValueError(
+                    "Operation would overwrite the old wheel - "
+                    "both objects' paths point at the same file."
+                )
+
         new_wf = WheelFile(
             file_or_path, mode,
             distname=distname,