init commit with repo structure and basic files

tests/fixtures.py

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+import os
+from typing import Callable
+
+import pytest
+
+
+@pytest.fixture
+def current_dir(request) -> str:
+    return os.path.dirname(request.module.__file__)
+
+
+@pytest.fixture
+def get_test_image(current_dir) -> Callable[[str], bytes]:
+    def f(name):
+        return open(os.path.join(current_dir, "test_images", name), "rb").read()
+
+    return f
+
+
+@pytest.fixture
+def save_test_image(current_dir) -> Callable[[str, bytes], None]:
+    def f(name: str, data: bytes):
+        open(os.path.join(current_dir, "test_images", name), "wb").write(data)
+
+    return f