Add preliminary test suite

Includes the following fix uncovered while writing tests:

- Fix an issue where `ChromaLocation.get_offsets` would throw an error
  on 4:4:4 subsampling

.github/workflows/lint.yml

@@ -26,11 +26,14 @@ jobs:
           pip install -r requirements-dev.txt
           pip install --force git+https://github.com/Setsugennoao/stgpytools.git
       - name: Running flake8
-        run: flake8 vstools
+        run: |
+          flake8 vstools
+          flake8 tests
       - name: Running mypy
         run: |
           echo "::add-matcher::.github/workflows/matchers/mypy.json"
           mypy --no-pretty vstools
+          mypy --no-pretty tests
           echo "::remove-matcher owner=mypy::"
         continue-on-error: true
       - name: Smoke test

.github/workflows/test.yml

@@ -0,0 +1,28 @@
+name: test
+
+on: [push, pull_request]
+
+jobs:
+  windows:
+    runs-on: windows-latest
+    strategy:
+      matrix:
+        versions:
+          - 68
+        python-version:
+          - '3.12'
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          python3 -m pip install --upgrade pip
+          pip install vapoursynth-portable==${{ matrix.versions }}
+          pip install -r requirements.txt
+          pip install -r requirements-dev.txt
+      - name: Running tests
+        run: pytest --cov-report=term-missing:skip-covered --cov=vstools tests

.gitignore

@@ -133,6 +133,7 @@ dmypy.json
 
 # code editors
 .vscode/
+.idea/
 
 # Pyre type checker
 .pyre/

pytest.ini

@@ -0,0 +1,2 @@
+[pytest]
+pythonpath = .

requirements-dev.txt

@@ -3,4 +3,6 @@ mypy>=1.11.2
 mypy-extensions>=1.0.0
 packaging>=24.0
 pycodestyle>=2.11.1
+pytest>=7.3.1
+pytest-cov>=5.0.0
 typing-extensions>=4.12.2