Drop dependency to pyfakefs

Create a temporary directory to manage our resource tests instead of
reyling on pyfakefs to mock it away for us. This also makes the code
more portable: all we need now is a way to create a temporary directory.
`pathlib` mostly abstracts away the other parts for us. Since we're
well-behaved, we clean up the temporary directory at the end of the
Python interpreter's life using `atexit` and `shutil.rmtree`.

This PR was written and tested with Python 3.9 which required some hacks
in `pyproject.toml` to make it work, it may require re-locking if CI
throws up.

Closes #679.

3 files changed, 70 insertions, 44 deletions

diff --git a/poetry.lock b/poetry.lock
index c5dad711..7fad2146 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1,4 +1,4 @@
-# This file is automatically @generated by Poetry and should not be changed by hand.
+# This file is automatically @generated by Poetry 1.4.1 and should not be changed by hand.
 
 [[package]]
 name = "anyio"
@@ -826,6 +826,26 @@ files = [
 ]
 
 [[package]]
+name = "importlib-metadata"
+version = "6.1.0"
+description = "Read metadata from Python packages"
+category = "main"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "importlib_metadata-6.1.0-py3-none-any.whl", hash = "sha256:ff80f3b5394912eb1b108fcfd444dc78b7f1f3e16b16188054bd01cb9cb86f09"},
+    {file = "importlib_metadata-6.1.0.tar.gz", hash = "sha256:43ce9281e097583d758c2c708c4376371261a02c34682491a8e98352365aad20"},
+]
+
+[package.dependencies]
+zipp = ">=0.5"
+
+[package.extras]
+docs = ["furo", "jaraco.packaging (>=9)", "jaraco.tidelift (>=1.4)", "rst.linker (>=1.9)", "sphinx (>=3.5)", "sphinx-lint"]
+perf = ["ipython"]
+testing = ["flake8 (<5)", "flufl.flake8", "importlib-resources (>=1.3)", "packaging", "pyfakefs", "pytest (>=6)", "pytest-black (>=0.3.7)", "pytest-checkdocs (>=2.4)", "pytest-cov", "pytest-enabler (>=1.3)", "pytest-flake8", "pytest-mypy (>=0.9.1)", "pytest-perf (>=0.9.2)"]
+
+[[package]]
 name = "libsass"
 version = "0.22.0"
 description = "Sass for Python: A straightforward binding of libsass for Python."
@@ -1122,18 +1142,6 @@ snowballstemmer = ">=2.2.0"
 toml = ["tomli (>=1.2.3)"]
 
 [[package]]
-name = "pyfakefs"
-version = "5.1.0"
-description = "pyfakefs implements a fake file system that mocks the Python file system modules."
-category = "dev"
-optional = false
-python-versions = ">=3.7"
-files = [
-    {file = "pyfakefs-5.1.0-py3-none-any.whl", hash = "sha256:e6f34a8224b41f1b1ab25aa8d430121dac42e3c6e981e01eae76b3343fba47d0"},
-    {file = "pyfakefs-5.1.0.tar.gz", hash = "sha256:316c6026640d14a6b4fbde71fd9674576d1b5710deda8fabde8aad51d785dbc3"},
-]
-
-[[package]]
 name = "pyflakes"
 version = "3.0.1"
 description = "passive checker of Python programs"
@@ -1534,6 +1542,22 @@ files = [
 [package.extras]
 brotli = ["Brotli"]
 
+[[package]]
+name = "zipp"
+version = "3.15.0"
+description = "Backport of pathlib-compatible object wrapper for zip files"
+category = "main"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "zipp-3.15.0-py3-none-any.whl", hash = "sha256:48904fc76a60e542af151aded95726c1a5c34ed43ab4134b597665c86d7ad556"},
+    {file = "zipp-3.15.0.tar.gz", hash = "sha256:112929ad649da941c23de50f356a2b5570c954b65150642bccdd66bf194d224b"},
+]
+
+[package.extras]
+docs = ["furo", "jaraco.packaging (>=9)", "jaraco.tidelift (>=1.4)", "rst.linker (>=1.9)", "sphinx (>=3.5)", "sphinx-lint"]
+testing = ["big-O", "flake8 (<5)", "jaraco.functools", "jaraco.itertools", "more-itertools", "pytest (>=6)", "pytest-black (>=0.3.7)", "pytest-checkdocs (>=2.4)", "pytest-cov", "pytest-enabler (>=1.3)", "pytest-flake8", "pytest-mypy (>=0.9.1)"]
+
 [metadata]
 lock-version = "2.0"
 python-versions = "3.10.*"
diff --git a/pydis_site/apps/content/tests/helpers.py b/pydis_site/apps/content/tests/helpers.py
index d897c024..1eab62be 100644
--- a/pydis_site/apps/content/tests/helpers.py
+++ b/pydis_site/apps/content/tests/helpers.py
@@ -1,12 +1,12 @@
+import atexit
+import shutil
+import tempfile
 from pathlib import Path
 
-from pyfakefs import fake_filesystem_unittest
+from django.test import TestCase
 
 
-# Set the module constant within Patcher to use the fake filesystem
-# https://jmcgeheeiv.github.io/pyfakefs/master/usage.html#modules-to-reload
-with fake_filesystem_unittest.Patcher() as _:
-    BASE_PATH = Path("res")
+BASE_PATH = Path(tempfile.mkdtemp(prefix='pydis-site-content-app-tests-'))
 
 
 # Valid markdown content with YAML metadata
@@ -50,7 +50,7 @@ PARSED_METADATA = {
 PARSED_CATEGORY_INFO = {"title": "Category Name", "description": "Description"}
 
 
-class MockPagesTestCase(fake_filesystem_unittest.TestCase):
+class MockPagesTestCase(TestCase):
     """
     TestCase with a fake filesystem for testing.
 
@@ -75,29 +75,32 @@ class MockPagesTestCase(fake_filesystem_unittest.TestCase):
 
     def setUp(self):
         """Create the fake filesystem."""
-        self.setUpPyfakefs()
-
-        self.fs.create_file(f"{BASE_PATH}/_info.yml", contents=CATEGORY_INFO)
-        self.fs.create_file(f"{BASE_PATH}/root.md", contents=MARKDOWN_WITH_METADATA)
-        self.fs.create_file(
-            f"{BASE_PATH}/root_without_metadata.md", contents=MARKDOWN_WITHOUT_METADATA
-        )
-        self.fs.create_file(f"{BASE_PATH}/not_a_page.md/_info.yml", contents=CATEGORY_INFO)
-        self.fs.create_file(f"{BASE_PATH}/category/_info.yml", contents=CATEGORY_INFO)
-        self.fs.create_file(
-            f"{BASE_PATH}/category/with_metadata.md", contents=MARKDOWN_WITH_METADATA
-        )
-        self.fs.create_file(f"{BASE_PATH}/category/subcategory/_info.yml", contents=CATEGORY_INFO)
-        self.fs.create_file(
-            f"{BASE_PATH}/category/subcategory/with_metadata.md", contents=MARKDOWN_WITH_METADATA
-        )
-        self.fs.create_file(
-            f"{BASE_PATH}/category/subcategory/without_metadata.md",
-            contents=MARKDOWN_WITHOUT_METADATA
-        )
+        Path(f"{BASE_PATH}/_info.yml").write_text(CATEGORY_INFO)
+        Path(f"{BASE_PATH}/root.md").write_text(MARKDOWN_WITH_METADATA)
+        Path(f"{BASE_PATH}/root_without_metadata.md").write_text(MARKDOWN_WITHOUT_METADATA)
+        Path(f"{BASE_PATH}/not_a_page.md").mkdir(exist_ok=True)
+        Path(f"{BASE_PATH}/not_a_page.md/_info.yml").write_text(CATEGORY_INFO)
+        Path(f"{BASE_PATH}/category").mkdir(exist_ok=True)
+        Path(f"{BASE_PATH}/category/_info.yml").write_text(CATEGORY_INFO)
+        Path(f"{BASE_PATH}/category/with_metadata.md").write_text(MARKDOWN_WITH_METADATA)
+        Path(f"{BASE_PATH}/category/subcategory").mkdir(exist_ok=True)
+        Path(f"{BASE_PATH}/category/subcategory/_info.yml").write_text(CATEGORY_INFO)
+        Path(
+            f"{BASE_PATH}/category/subcategory/with_metadata.md"
+        ).write_text(MARKDOWN_WITH_METADATA)
+        Path(
+            f"{BASE_PATH}/category/subcategory/without_metadata.md"
+        ).write_text(MARKDOWN_WITHOUT_METADATA)
 
         temp = f"{BASE_PATH}/tmp"  # noqa: S108
-        self.fs.create_file(f"{temp}/_info.yml", contents=CATEGORY_INFO)
-        self.fs.create_file(f"{temp}.md", contents=MARKDOWN_WITH_METADATA)
-        self.fs.create_file(f"{temp}/category/_info.yml", contents=CATEGORY_INFO)
-        self.fs.create_dir(f"{temp}/category/subcategory_without_info")
+        Path(f"{temp}").mkdir(exist_ok=True)
+        Path(f"{temp}/_info.yml").write_text(CATEGORY_INFO)
+        Path(f"{temp}.md").write_text(MARKDOWN_WITH_METADATA)
+        Path(f"{temp}/category").mkdir(exist_ok=True)
+        Path(f"{temp}/category/_info.yml").write_text(CATEGORY_INFO)
+        Path(f"{temp}/category/subcategory_without_info").mkdir(exist_ok=True)
+
+    @classmethod
+    def setUpTestData(cls):
+        # May get called multiple times - ignore erorrs in that case.
+        atexit.register(shutil.rmtree, BASE_PATH, ignore_errors=True)
diff --git a/pyproject.toml b/pyproject.toml
index 21bc26d7..21857f84 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -45,7 +45,6 @@ pre-commit = "3.2.0"
 
 [tool.poetry.group.test.dependencies]
 coverage = "7.2.2"
-pyfakefs = "5.1.0"
 
 [build-system]
 requires = ["poetry-core>=1.2.0"]