get pixel size by counting bytes in 1x1 image

Tests/helper.py

@@ -13,7 +13,7 @@ import sysconfig
 import tempfile
 from functools import lru_cache
 from io import BytesIO
-from typing import Any, Callable, NamedTuple, Sequence
+from typing import Any, Callable, Sequence
 
 import pytest
 from packaging.version import parse as parse_version
@@ -29,39 +29,32 @@ elif "GITHUB_ACTIONS" in os.environ:
     uploader = "github_actions"
 
 
-class ImageModeInfo(NamedTuple):
-    name: str
-    pixel_size: int
-
-
-image_modes = (
-    ImageModeInfo("1", 1),
-    ImageModeInfo("L", 1),
-    ImageModeInfo("LA", 4),
-    ImageModeInfo("La", 4),
-    ImageModeInfo("P", 1),
-    ImageModeInfo("PA", 4),
-    ImageModeInfo("F", 4),
-    ImageModeInfo("I", 4),
-    ImageModeInfo("I;16", 2),
-    ImageModeInfo("I;16L", 2),
-    ImageModeInfo("I;16B", 2),
-    ImageModeInfo("I;16N", 2),
-    ImageModeInfo("RGB", 4),
-    ImageModeInfo("RGBA", 4),
-    ImageModeInfo("RGBa", 4),
-    ImageModeInfo("RGBX", 4),
-    ImageModeInfo("BGR;15", 2),
-    ImageModeInfo("BGR;16", 2),
-    ImageModeInfo("BGR;24", 3),
-    ImageModeInfo("CMYK", 4),
-    ImageModeInfo("YCbCr", 4),
-    ImageModeInfo("HSV", 4),
-    ImageModeInfo("LAB", 4),
+image_mode_names = (
+    "1",
+    "L",
+    "LA",
+    "La",
+    "P",
+    "PA",
+    "F",
+    "I",
+    "I;16",
+    "I;16L",
+    "I;16B",
+    "I;16N",
+    "RGB",
+    "RGBA",
+    "RGBa",
+    "RGBX",
+    "BGR;15",
+    "BGR;16",
+    "BGR;24",
+    "CMYK",
+    "YCbCr",
+    "HSV",
+    "LAB",
 )
 
-image_mode_names = [mode.name for mode in image_modes]
-
 
 def upload(a: Image.Image, b: Image.Image) -> str | None:
     if uploader == "show":

Tests/test_image.py

@@ -23,14 +23,12 @@ from PIL import (
 )
 
 from .helper import (
-    ImageModeInfo,
     assert_image_equal,
     assert_image_equal_tofile,
     assert_image_similar_tofile,
     assert_not_all_same,
     hopper,
     image_mode_names,
-    image_modes,
     is_win32,
     mark_if_feature_version,
     skip_unless_feature,
@@ -1036,13 +1034,20 @@ class TestImageBytes:
         reloaded.frombytes(source_bytes)
         assert reloaded.tobytes() == source_bytes
 
-    @pytest.mark.parametrize("mode", image_modes)
-    def test_getdata_putdata(self, mode: ImageModeInfo) -> None:
-        im = Image.new(mode.name, (2, 2))
-        source_bytes = bytes(range(im.width * im.height * mode.pixel_size))
+    @pytest.mark.parametrize("mode", image_mode_names)
+    def test_getdata_putdata(self, mode: str) -> None:
+        # create an image with 1 pixel to get its pixel size
+        im = Image.new(mode, (1, 1))
+        pixel_size = len(im.tobytes())
+
+        # create a new image with incrementing byte values
+        im = Image.new(mode, (2, 2))
+        source_bytes = bytes(range(im.width * im.height * pixel_size))
         im.frombytes(source_bytes)
 
-        reloaded = Image.new(mode.name, im.size)
+        # copy the data from the previous image to a new image
+        # and check that they are the same
+        reloaded = Image.new(mode, im.size)
         reloaded.putdata(im.getdata())
         assert_image_equal(im, reloaded)