Add script to generate Nuspec wrapper library.

This tool will help facilitate development of nupkg and chocolately
processors and associated libraries. The generated output is included in
this commit.

.flake8

@@ -18,6 +18,7 @@ ignore = E127, E128, E203, E265, E266, E402, E501, E722, P207, P208, W503
 exclude =
   .git,
   .hg,
+  Code/nupkg/generated/*,
 # This will be fine-tuned over time
 max-complexity = 65
 # Ignore the line length limits on tests, where we have in-line plist strings

.pre-commit-config.yaml

@@ -1,3 +1,4 @@
+exclude: '^Code/nuget/generated/.*$'
 repos:
 -   repo: https://github.com/python/black
     rev: 19.10b0

Scripts/regenerate_nuspec_ds.py

@@ -0,0 +1,119 @@
+#!/usr/local/autopkg/python
+#
+# 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.
+"""
+Regenerates the NuSpec XML schema Python wrapper module from upstream source.
+
+Downloads the latest NuSpec XSD from the GitHub NuGet/NuGet.Client Git repository,
+and creates a wrapper library using the `generateDS` utility.
+"""
+import os
+import sys
+
+# isort: off
+# Ensure that we can find autopkglib no matter where we run this.
+AUTOPKG_TOP: str = os.path.abspath(
+    os.path.join(os.path.dirname(__file__), "..", "Code")
+)
+sys.path.insert(0, AUTOPKG_TOP)
+# isort: on
+
+import ssl
+import subprocess
+from argparse import ArgumentParser
+from typing import List
+from urllib.request import urlopen
+
+from autopkglib import find_binary
+
+SCHEMA_SOURCE_URL: str = (
+    "https://raw.githubusercontent.com/NuGet/NuGet.Client"
+    "/dev/src/NuGet.Core/NuGet.Packaging/compiler/resources/nuspec.xsd"
+)
+
+# Latest known version of the Nuspec XML schema namespace. Found by running `choco new`.
+# Used because the schema source contains placeholders for the namespace.
+SCHEMA_XMLNS: bytes = b"http://schemas.microsoft.com/packaging/2015/06/nuspec.xsd"
+
+
+def get_schema_source(url: str, xmlns: bytes = SCHEMA_XMLNS) -> bytes:
+    """Fetch the latest XML schema and replace `{0}` with the given XML namespace."""
+    context = ssl.SSLContext()
+    context.verify_mode = ssl.CERT_REQUIRED
+    context.check_hostname = True
+    context.load_default_certs()
+
+    with urlopen(SCHEMA_SOURCE_URL, context=context) as res:
+        return res.read().replace(b"{0}", xmlns)
+
+
+def run_generateds(generateds_binary: str, output_path: str, schema_source: bytes):
+    """Generate python wrapper library around the provided XML schema."""
+    call_res = subprocess.run(
+        [
+            generateds_binary,
+            # Enable using Python __slots__ object annotation to improve performance.
+            "--member-specs=dict",
+            "--enable-slots",
+            # Generate methods to write to files and validate objects.
+            "--export=write validate",
+            # Do not prompt and force overwrite existing files.
+            "--no-questions",
+            "-f",
+            "-o",
+            output_path,
+            "-",
+        ],
+        input=schema_source,
+    )
+    return call_res.returncode
+
+
+def main(input_args: List[str]) -> int:
+    parser = ArgumentParser(
+        description="Regenerate the python wrapper library around the nuget xml schema."
+    )
+    parser.add_argument(
+        "--output-path",
+        help=(
+            "Full path to the output file. "
+            "Intermediate directories are created as needed."
+        ),
+        required=True,
+    )
+    parser.add_argument(
+        "--generateds-binary",
+        help="Path to generateDS. If not specified, defaults to looking in $env:PATH",
+        default=None,
+    )
+    args = parser.parse_args(input_args)
+
+    if args.generateds_binary is None:
+        args.generateds_binary = find_binary("generateDS")
+
+    if args.generateds_binary is None:
+        print("ERROR: Unable to locate generateDS! Try passing --generateds-binary.")
+        return 1
+
+    # Create any directories as needed.
+    output_dir = os.path.abspath(os.path.dirname(args.output_path))
+    print(f"Generated output is being written to: {output_dir}")
+    os.makedirs(output_dir, exist_ok=True)
+
+    return run_generateds(
+        args.generateds_binary, args.output_path, get_schema_source(SCHEMA_SOURCE_URL)
+    )
+
+
+if __name__ == "__main__":
+    sys.exit(main(sys.argv[1:]))

requirements.txt

@@ -147,4 +147,8 @@ pyobjc-framework-VideoSubscriberAccount==6.0.1; sys_platform == 'darwin'
 pyobjc-framework-VideoToolbox==6.0.1; sys_platform == 'darwin'
 pyobjc-framework-Vision==6.0.1; sys_platform == 'darwin'
 pyobjc-framework-WebKit==6.0.1; sys_platform == 'darwin'
-pyobjc==6.0.1; sys_platform == 'darwin'
+pyobjc==6.0.1; sys_platform == 'darwin'
+#
+# Windows Requirements
+#
+generateDS==2.35.24; sys_platform == 'win32'