Tests: Convert internal check() functions to use parametrize

Tests/test_file_gif.py

@@ -158,39 +158,42 @@ def test_bilevel(optimize):
     assert test_bilevel(1) == 799
 
 
-def test_optimize_correctness():
-    # 256 color Palette image, posterize to > 128 and < 128 levels
-    # Size bigger and smaller than 512x512
+@pytest.mark.parametrize(
+    "colors, size, expected_palette_length",
+    (
+        # These do optimize the palette
+        (256, 511, 256),
+        (255, 511, 255),
+        (129, 511, 129),
+        (128, 511, 128),
+        (64, 511, 64),
+        (4, 511, 4),
+        # These don't optimize the palette
+        (128, 513, 256),
+        (64, 513, 256),
+        (4, 513, 256),
+    ),
+)
+def test_optimize_correctness(colors, size, expected_palette_length):
+    # 256 color Palette image, posterize to > 128 and < 128 levels.
+    # Size bigger and smaller than 512x512.
     # Check the palette for number of colors allocated.
-    # Check for correctness after conversion back to RGB
-    def check(colors, size, expected_palette_length):
-        # make an image with empty colors in the start of the palette range
-        im = Image.frombytes(
-            "P", (colors, colors), bytes(range(256 - colors, 256)) * colors
-        )
-        im = im.resize((size, size))
-        outfile = BytesIO()
-        im.save(outfile, "GIF")
-        outfile.seek(0)
-        with Image.open(outfile) as reloaded:
-            # check palette length
-            palette_length = max(i + 1 for i, v in enumerate(reloaded.histogram()) if v)
-            assert expected_palette_length == palette_length
-
-            assert_image_equal(im.convert("RGB"), reloaded.convert("RGB"))
-
-    # These do optimize the palette
-    check(256, 511, 256)
-    check(255, 511, 255)
-    check(129, 511, 129)
-    check(128, 511, 128)
-    check(64, 511, 64)
-    check(4, 511, 4)
-
-    # These don't optimize the palette
-    check(128, 513, 256)
-    check(64, 513, 256)
-    check(4, 513, 256)
+    # Check for correctness after conversion back to RGB.
+
+    # make an image with empty colors in the start of the palette range
+    im = Image.frombytes(
+        "P", (colors, colors), bytes(range(256 - colors, 256)) * colors
+    )
+    im = im.resize((size, size))
+    outfile = BytesIO()
+    im.save(outfile, "GIF")
+    outfile.seek(0)
+    with Image.open(outfile) as reloaded:
+        # check palette length
+        palette_length = max(i + 1 for i, v in enumerate(reloaded.histogram()) if v)
+        assert expected_palette_length == palette_length
+
+        assert_image_equal(im.convert("RGB"), reloaded.convert("RGB"))
 
 
 def test_optimize_full_l():

Tests/test_image_mode.py

@@ -1,3 +1,5 @@
+import pytest
+
 from PIL import Image, ImageMode
 
 from .helper import hopper
@@ -49,23 +51,25 @@ def test_sanity():
     assert m.typestr == "|u1"
 
 
-def test_properties():
-    def check(mode, *result):
-        signature = (
-            Image.getmodebase(mode),
-            Image.getmodetype(mode),
-            Image.getmodebands(mode),
-            Image.getmodebandnames(mode),
-        )
-        assert signature == result
-
-    check("1", "L", "L", 1, ("1",))
-    check("L", "L", "L", 1, ("L",))
-    check("P", "P", "L", 1, ("P",))
-    check("I", "L", "I", 1, ("I",))
-    check("F", "L", "F", 1, ("F",))
-    check("RGB", "RGB", "L", 3, ("R", "G", "B"))
-    check("RGBA", "RGB", "L", 4, ("R", "G", "B", "A"))
-    check("RGBX", "RGB", "L", 4, ("R", "G", "B", "X"))
-    check("CMYK", "RGB", "L", 4, ("C", "M", "Y", "K"))
-    check("YCbCr", "RGB", "L", 3, ("Y", "Cb", "Cr"))
+@pytest.mark.parametrize(
+    "mode, expected_base, expected_type, expected_bands, expected_band_names",
+    (
+        ("1", "L", "L", 1, ("1",)),
+        ("L", "L", "L", 1, ("L",)),
+        ("P", "P", "L", 1, ("P",)),
+        ("I", "L", "I", 1, ("I",)),
+        ("F", "L", "F", 1, ("F",)),
+        ("RGB", "RGB", "L", 3, ("R", "G", "B")),
+        ("RGBA", "RGB", "L", 4, ("R", "G", "B", "A")),
+        ("RGBX", "RGB", "L", 4, ("R", "G", "B", "X")),
+        ("CMYK", "RGB", "L", 4, ("C", "M", "Y", "K")),
+        ("YCbCr", "RGB", "L", 3, ("Y", "Cb", "Cr")),
+    ),
+)
+def test_properties(
+    mode, expected_base, expected_type, expected_bands, expected_band_names
+):
+    assert Image.getmodebase(mode) == expected_base
+    assert Image.getmodetype(mode) == expected_type
+    assert Image.getmodebands(mode) == expected_bands
+    assert Image.getmodebandnames(mode) == expected_band_names