Ensure valid CSV content is used for RECORD file

This change makes us of the csv module, to ensure valid CSV is used when 
writing the RECORD file for the wheel packages.

Resolves: python-poetry/poetry#2052

poetry/core/masonry/builders/wheel.py

@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 
 import contextlib
+import csv
 import hashlib
 import logging
 import os
@@ -12,11 +13,13 @@
 import zipfile
 
 from base64 import urlsafe_b64encode
+from io import BytesIO
 from io import StringIO
 
 from packaging.tags import sys_tags
 from poetry.core import __version__
 from poetry.core.semver import parse_constraint
+from poetry.core.utils._compat import PY2
 from poetry.core.utils._compat import decode
 
 from ..utils.helpers import escape_name
@@ -37,7 +40,6 @@
 
 
 class WheelBuilder(Builder):
-
     format = "wheel"
 
     def __init__(self, poetry, target_dir=None, original=None):
@@ -179,10 +181,21 @@ def _write_metadata(self, wheel):
     def _write_record(self, wheel):
         # Write a record of the files in the wheel
         with self._write_to_zip(wheel, self.dist_info + "/RECORD") as f:
+            record = StringIO() if not PY2 else BytesIO()
+
+            csv_writer = csv.writer(
+                record,
+                delimiter=csv.excel.delimiter,
+                quotechar=csv.excel.quotechar,
+                lineterminator="\n",
+            )
             for path, hash, size in self._records:
-                f.write("{},sha256={},{}\n".format(path, hash, size))
+                csv_writer.writerow((path, "sha256={}".format(hash), size))
+
             # RECORD itself is recorded with no hash or size
-            f.write(self.dist_info + "/RECORD,,\n")
+            csv_writer.writerow((self.dist_info + "/RECORD", "", ""))
+
+            f.write(decode(record.getvalue()))
 
     @property
     def dist_info(self):  # type: () -> str

tests/masonry/builders/fixtures/comma_file/pyproject.toml

@@ -0,0 +1,12 @@
+[tool.poetry]
+name = "comma-file"
+version = "1.2.3"
+description = "Some description."
+authors = [
+    "Sébastien Eustace <sebastien@eustace.io>"
+]
+[tool.poetry.dependencies]
+python = "^3.6"
+
+[tool.poetry.dev-dependencies]
+

tests/masonry/builders/test_wheel.py

@@ -198,3 +198,16 @@ def test_wheel_package_pep_561_stub_only_includes_typed_marker():
 
     with zipfile.ZipFile(str(whl)) as z:
         assert "pkg-stubs/py.typed" in z.namelist()
+
+
+def test_wheel_with_file_with_comma():
+    root = fixtures_dir / "comma_file"
+    WheelBuilder.make(Factory().create_poetry(root))
+
+    whl = root / "dist" / "comma_file-1.2.3-py3-none-any.whl"
+
+    assert whl.exists()
+
+    with zipfile.ZipFile(str(whl)) as z:
+        records = z.read("comma_file-1.2.3.dist-info/RECORD")
+        assert '\n"comma_file/a,b.py"' in records.decode()