Use packaging.metadata to parse and validate upload metadata (#14718)

* Use packaging.metadata to parse/validate the metadata

* Use a temporary fork of packaging

* Linting

* requires_python is already special-cased

* Bump supported metadata versions

* Small normalization change in requires_dist output

* Source our _FORM_TO_RAW_MAPPING from packaging

* Normalize dynamic values

---------

Co-authored-by: Dustin Ingram <di@users.noreply.github.com>

tests/unit/forklift/test_forms.py

@@ -0,0 +1,78 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import pretend
+import pytest
+
+from webob.multidict import MultiDict
+from wtforms.validators import ValidationError
+
+from warehouse.forklift.forms import UploadForm, _validate_pep440_version
+
+
+class TestValidation:
+    @pytest.mark.parametrize("version", ["1.0", "30a1", "1!1", "1.0-1", "v1.0"])
+    def test_validates_valid_pep440_version(self, version):
+        form, field = pretend.stub(), pretend.stub(data=version)
+        _validate_pep440_version(form, field)
+
+    @pytest.mark.parametrize("version", ["dog", "1.0.dev.a1"])
+    def test_validates_invalid_pep440_version(self, version):
+        form, field = pretend.stub(), pretend.stub(data=version)
+        with pytest.raises(ValidationError):
+            _validate_pep440_version(form, field)
+
+
+class TestUploadForm:
+    @pytest.mark.parametrize(
+        "data",
+        [
+            # Test for singular supported digests
+            {"filetype": "sdist", "md5_digest": "bad"},
+            {"filetype": "bdist_wheel", "pyversion": "3.4", "md5_digest": "bad"},
+            {"filetype": "sdist", "sha256_digest": "bad"},
+            {"filetype": "bdist_wheel", "pyversion": "3.4", "sha256_digest": "bad"},
+            {"filetype": "sdist", "blake2_256_digest": "bad"},
+            {"filetype": "bdist_wheel", "pyversion": "3.4", "blake2_256_digest": "bad"},
+            # Tests for multiple digests passing through
+            {
+                "filetype": "sdist",
+                "md5_digest": "bad",
+                "sha256_digest": "bad",
+                "blake2_256_digest": "bad",
+            },
+            {
+                "filetype": "bdist_wheel",
+                "pyversion": "3.4",
+                "md5_digest": "bad",
+                "sha256_digest": "bad",
+                "blake2_256_digest": "bad",
+            },
+        ],
+    )
+    def test_full_validate_valid(self, data):
+        form = UploadForm(MultiDict(data))
+        form.full_validate()
+
+    @pytest.mark.parametrize(
+        "data",
+        [
+            {"filetype": "sdist", "pyversion": "3.4"},
+            {"filetype": "bdist_wheel"},
+            {"filetype": "bdist_wheel", "pyversion": "3.4"},
+        ],
+    )
+    def test_full_validate_invalid(self, data):
+        form = UploadForm(MultiDict(data))
+        with pytest.raises(ValidationError):
+            form.full_validate()