fix(tests): review test_tools.py relevance & robustness (#433)

Author: BoboTiG

pyproject.toml

@@ -140,7 +140,7 @@ addopts = """
   --showlocals
   --strict-markers
   -r fE
-  -vvv
+  -v
   --cov=src/mss
   --cov-report=term-missing:skip-covered
 """

src/tests/test_tools.py

@@ -2,70 +2,58 @@
 Source: https://github.com/BoboTiG/python-mss.
 """
 
-import hashlib
-import zlib
-from collections.abc import Callable
+from __future__ import annotations
+
+import io
 from pathlib import Path
+from typing import TYPE_CHECKING
 
 import pytest
 
-from mss.base import MSSBase
 from mss.tools import to_png
 
+if TYPE_CHECKING:
+    from collections.abc import Callable
+
+    from mss.base import MSSBase
+
 WIDTH = 10
 HEIGHT = 10
-MD5SUM = "ee1b645cc989cbfc48e613b395a929d3d79a922b77b9b38e46647ff6f74acef5"
+
+
+def assert_is_valid_png(*, raw: bytes | None = None, file: Path | None = None) -> None:
+    Image = pytest.importorskip("PIL.Image", reason="PIL module not available.")  # noqa: N806
+
+    assert bool(Image.open(io.BytesIO(raw) if raw is not None else file).tobytes())
+    try:
+        Image.open(io.BytesIO(raw) if raw is not None else file).verify()
+    except Exception:  # noqa: BLE001
+        pytest.fail(reason="invalid PNG data")
 
 
 def test_bad_compression_level(mss_impl: Callable[..., MSSBase]) -> None:
-    with mss_impl(compression_level=42) as sct, pytest.raises(zlib.error):
+    with mss_impl(compression_level=42) as sct, pytest.raises(Exception, match="Bad compression level"):
         sct.shot()
 
 
-def test_compression_level(mss_impl: Callable[..., MSSBase]) -> None:
-    data = b"rgb" * WIDTH * HEIGHT
-    output = Path(f"{WIDTH}x{HEIGHT}.png")
-
-    with mss_impl() as sct:
-        to_png(data, (WIDTH, HEIGHT), level=sct.compression_level, output=output)
-
-    assert hashlib.sha256(output.read_bytes()).hexdigest() == MD5SUM
-
-
-@pytest.mark.parametrize(
-    ("level", "checksum"),
-    [
-        (0, "547191069e78eef1c5899f12c256dd549b1338e67c5cd26a7cbd1fc5a71b83aa"),
-        (1, "841665ec73b641dfcafff5130b497f5c692ca121caeb06b1d002ad3de5c77321"),
-        (2, "b11107163207f68f36294deb3f8e6b6a5a11399a532917bdd59d1d5f1117d4d0"),
-        (3, "31278bad8c1c077c715ac4f3b497694a323a71a87c5ff8bdc7600a36bd8d8c96"),
-        (4, "8f7237e1394d9ddc71fcb1fa4a2c2953087562ef6eac85d32d8154b61b287fb0"),
-        (5, "83a55f161bad2d511b222dcd32059c9adf32c3238b65f9aa576f19bc0a6c8fec"),
-        (6, "ee1b645cc989cbfc48e613b395a929d3d79a922b77b9b38e46647ff6f74acef5"),
-        (7, "85f8d1b01cef926c111b194229bd6c01e2a65b18b4dd902293698e6de8f4e9ac"),
-        (8, "85f8d1b01cef926c111b194229bd6c01e2a65b18b4dd902293698e6de8f4e9ac"),
-        (9, "85f8d1b01cef926c111b194229bd6c01e2a65b18b4dd902293698e6de8f4e9ac"),
-    ],
-)
-def test_compression_levels(level: int, checksum: str) -> None:
+@pytest.mark.parametrize("level", range(10))
+def test_compression_level(level: int) -> None:
     data = b"rgb" * WIDTH * HEIGHT
     raw = to_png(data, (WIDTH, HEIGHT), level=level)
     assert isinstance(raw, bytes)
-    sha256 = hashlib.sha256(raw).hexdigest()
-    assert sha256 == checksum
+    assert_is_valid_png(raw=raw)
 
 
 def test_output_file() -> None:
     data = b"rgb" * WIDTH * HEIGHT
     output = Path(f"{WIDTH}x{HEIGHT}.png")
     to_png(data, (WIDTH, HEIGHT), output=output)
-
     assert output.is_file()
-    assert hashlib.sha256(output.read_bytes()).hexdigest() == MD5SUM
+    assert_is_valid_png(file=output)
 
 
 def test_output_raw_bytes() -> None:
     data = b"rgb" * WIDTH * HEIGHT
     raw = to_png(data, (WIDTH, HEIGHT))
     assert isinstance(raw, bytes)
-    assert hashlib.sha256(raw).hexdigest() == MD5SUM
+    assert_is_valid_png(raw=raw)