Added type hints

Tests/test_image_convert.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from pathlib import Path
+
 import pytest
 
 from PIL import Image
@@ -7,8 +9,8 @@ from PIL import Image
 from .helper import assert_image, assert_image_equal, assert_image_similar, hopper
 
 
-def test_sanity():
+def test_sanity() -> None:
-    def convert(im, mode):
+    def convert(im: Image.Image, mode: str) -> None:
         out = im.convert(mode)
         assert out.mode == mode
         assert out.size == im.size
@@ -40,13 +42,13 @@ def test_sanity():
             convert(im, output_mode)
 
 
-def test_unsupported_conversion():
+def test_unsupported_conversion() -> None:
     im = hopper()
     with pytest.raises(ValueError):
         im.convert("INVALID")
 
 
-def test_default():
+def test_default() -> None:
     im = hopper("P")
     assert im.mode == "P"
     converted_im = im.convert()
@@ -62,18 +64,18 @@ def test_default():
 # ref https://github.com/python-pillow/Pillow/issues/274
 
 
-def _test_float_conversion(im):
+def _test_float_conversion(im: Image.Image) -> None:
     orig = im.getpixel((5, 5))
     converted = im.convert("F").getpixel((5, 5))
     assert orig == converted
 
 
-def test_8bit():
+def test_8bit() -> None:
     with Image.open("Tests/images/hopper.jpg") as im:
         _test_float_conversion(im.convert("L"))
 
 
-def test_16bit():
+def test_16bit() -> None:
     with Image.open("Tests/images/16bit.cropped.tif") as im:
         _test_float_conversion(im)
 
@@ -83,19 +85,19 @@ def test_16bit():
         assert im_i16.getpixel((0, 0)) == 65535
 
 
-def test_16bit_workaround():
+def test_16bit_workaround() -> None:
     with Image.open("Tests/images/16bit.cropped.tif") as im:
         _test_float_conversion(im.convert("I"))
 
 
-def test_opaque():
+def test_opaque() -> None:
     alpha = hopper("P").convert("PA").getchannel("A")
 
     solid = Image.new("L", (128, 128), 255)
     assert_image_equal(alpha, solid)
 
 
-def test_rgba_p():
+def test_rgba_p() -> None:
     im = hopper("RGBA")
     im.putalpha(hopper("L"))
 
@@ -105,14 +107,14 @@ def test_rgba_p():
     assert_image_similar(im, comparable, 20)
 
 
-def test_rgba():
+def test_rgba() -> None:
     with Image.open("Tests/images/transparent.png") as im:
         assert im.mode == "RGBA"
 
         assert_image_similar(im.convert("RGBa").convert("RGB"), im.convert("RGB"), 1.5)
 
 
-def test_trns_p(tmp_path):
+def test_trns_p(tmp_path: Path) -> None:
     im = hopper("P")
     im.info["transparency"] = 0
 
@@ -131,7 +133,7 @@ def test_trns_p(tmp_path):
 
 
 @pytest.mark.parametrize("mode", ("LA", "PA", "RGBA"))
-def test_trns_p_transparency(mode):
+def test_trns_p_transparency(mode: str) -> None:
     # Arrange
     im = hopper("P")
     im.info["transparency"] = 128
@@ -148,7 +150,7 @@ def test_trns_p_transparency(mode):
         assert converted_im.palette is None
 
 
-def test_trns_l(tmp_path):
+def test_trns_l(tmp_path: Path) -> None:
     im = hopper("L")
     im.info["transparency"] = 128
 
@@ -171,7 +173,7 @@ def test_trns_l(tmp_path):
     im_p.save(f)
 
 
-def test_trns_RGB(tmp_path):
+def test_trns_RGB(tmp_path: Path) -> None:
     im = hopper("RGB")
     im.info["transparency"] = im.getpixel((0, 0))
 
@@ -201,7 +203,7 @@ def test_trns_RGB(tmp_path):
 
 
 @pytest.mark.parametrize("convert_mode", ("L", "LA", "I"))
-def test_l_macro_rounding(convert_mode):
+def test_l_macro_rounding(convert_mode: str) -> None:
     for mode in ("P", "PA"):
         im = Image.new(mode, (1, 1))
         im.palette.getcolor((0, 1, 2))
@@ -214,7 +216,7 @@ def test_l_macro_rounding(convert_mode):
         assert converted_color == 1
 
 
-def test_gif_with_rgba_palette_to_p():
+def test_gif_with_rgba_palette_to_p() -> None:
     # See https://github.com/python-pillow/Pillow/issues/2433
     with Image.open("Tests/images/hopper.gif") as im:
         im.info["transparency"] = 255
@@ -226,7 +228,7 @@ def test_gif_with_rgba_palette_to_p():
     im_p.load()
 
 
-def test_p_la():
+def test_p_la() -> None:
     im = hopper("RGBA")
     alpha = hopper("L")
     im.putalpha(alpha)
@@ -236,7 +238,7 @@ def test_p_la():
     assert_image_similar(alpha, comparable, 5)
 
 
-def test_p2pa_alpha():
+def test_p2pa_alpha() -> None:
     with Image.open("Tests/images/tiny.png") as im:
         assert im.mode == "P"
 
@@ -250,13 +252,13 @@ def test_p2pa_alpha():
             assert im_a.getpixel((x, y)) == alpha
 
 
-def test_p2pa_palette():
+def test_p2pa_palette() -> None:
     with Image.open("Tests/images/tiny.png") as im:
         im_pa = im.convert("PA")
     assert im_pa.getpalette() == im.getpalette()
 
 
-def test_matrix_illegal_conversion():
+def test_matrix_illegal_conversion() -> None:
     # Arrange
     im = hopper("CMYK")
     # fmt: off
@@ -272,7 +274,7 @@ def test_matrix_illegal_conversion():
         im.convert(mode="CMYK", matrix=matrix)
 
 
-def test_matrix_wrong_mode():
+def test_matrix_wrong_mode() -> None:
     # Arrange
     im = hopper("L")
     # fmt: off
@@ -289,7 +291,7 @@ def test_matrix_wrong_mode():
 
 
 @pytest.mark.parametrize("mode", ("RGB", "L"))
-def test_matrix_xyz(mode):
+def test_matrix_xyz(mode: str) -> None:
     # Arrange
     im = hopper("RGB")
     im.info["transparency"] = (255, 0, 0)
@@ -317,7 +319,7 @@ def test_matrix_xyz(mode):
             assert converted_im.info["transparency"] == 105
 
 
-def test_matrix_identity():
+def test_matrix_identity() -> None:
     # Arrange
     im = hopper("RGB")
     # fmt: off

Tests/test_image_copy.py

@@ -10,7 +10,7 @@ from .helper import hopper, skip_unless_feature
 
 
 @pytest.mark.parametrize("mode", ("1", "P", "L", "RGB", "I", "F"))
-def test_copy(mode):
+def test_copy(mode: str) -> None:
     cropped_coordinates = (10, 10, 20, 20)
     cropped_size = (10, 10)
 
@@ -39,7 +39,7 @@ def test_copy(mode):
     assert out.size == cropped_size
 
 
-def test_copy_zero():
+def test_copy_zero() -> None:
     im = Image.new("RGB", (0, 0))
     out = im.copy()
     assert out.mode == im.mode
@@ -47,7 +47,7 @@ def test_copy_zero():
 
 
 @skip_unless_feature("libtiff")
-def test_deepcopy():
+def test_deepcopy() -> None:
     with Image.open("Tests/images/g4_orientation_5.tif") as im:
         out = copy.deepcopy(im)
     assert out.size == (590, 88)

Tests/test_image_crop.py

@@ -8,7 +8,7 @@ from .helper import assert_image_equal, hopper
 
 
 @pytest.mark.parametrize("mode", ("1", "P", "L", "RGB", "I", "F"))
-def test_crop(mode):
+def test_crop(mode: str) -> None:
     im = hopper(mode)
     assert_image_equal(im.crop(), im)
 
@@ -17,8 +17,8 @@ def test_crop(mode):
     assert cropped.size == (50, 50)
 
 
-def test_wide_crop():
+def test_wide_crop() -> None:
-    def crop(*bbox):
+    def crop(*bbox: int) -> tuple[int, ...]:
         i = im.crop(bbox)
         h = i.histogram()
         while h and not h[-1]:
@@ -47,14 +47,14 @@ def test_wide_crop():
 
 
 @pytest.mark.parametrize("box", ((8, 2, 2, 8), (2, 8, 8, 2), (8, 8, 2, 2)))
-def test_negative_crop(box):
+def test_negative_crop(box: tuple[int, int, int, int]) -> None:
     im = Image.new("RGB", (10, 10))
 
     with pytest.raises(ValueError):
         im.crop(box)
 
 
-def test_crop_float():
+def test_crop_float() -> None:
     # Check cropping floats are rounded to nearest integer
     # https://github.com/python-pillow/Pillow/issues/1744
 
@@ -69,7 +69,7 @@ def test_crop_float():
     assert cropped.size == (3, 5)
 
 
-def test_crop_crash():
+def test_crop_crash() -> None:
     # Image.crop crashes prepatch with an access violation
     # apparently a use after free on Windows, see
     # https://github.com/python-pillow/Pillow/issues/1077
@@ -87,7 +87,7 @@ def test_crop_crash():
     img.load()
 
 
-def test_crop_zero():
+def test_crop_zero() -> None:
     im = Image.new("RGB", (0, 0), "white")
 
     cropped = im.crop((0, 0, 0, 0))

Tests/test_image_frombytes.py

@@ -8,7 +8,7 @@ from .helper import assert_image_equal, hopper
 
 
 @pytest.mark.parametrize("data_type", ("bytes", "memoryview"))
-def test_sanity(data_type):
+def test_sanity(data_type) -> None:
     im1 = hopper()
 
     data = im1.tobytes()

Tests/test_image_fromqimage.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import warnings
+from typing import Generator
 
 import pytest
 
@@ -18,7 +19,7 @@ pytestmark = pytest.mark.skipif(
 
 
 @pytest.fixture
-def test_images():
+def test_images() -> Generator[Image.Image, None, None]:
     ims = [
         hopper(),
         Image.open("Tests/images/transparent.png"),
@@ -31,7 +32,7 @@ def test_images():
             im.close()
 
 
-def roundtrip(expected):
+def roundtrip(expected: Image.Image) -> None:
     # PIL -> Qt
     intermediate = expected.toqimage()
     # Qt -> PIL
@@ -43,26 +44,26 @@ def roundtrip(expected):
         assert_image_equal(result, expected.convert("RGB"))
 
 
-def test_sanity_1(test_images):
+def test_sanity_1(test_images: Generator[Image.Image, None, None]) -> None:
     for im in test_images:
         roundtrip(im.convert("1"))
 
 
-def test_sanity_rgb(test_images):
+def test_sanity_rgb(test_images: Generator[Image.Image, None, None]) -> None:
     for im in test_images:
         roundtrip(im.convert("RGB"))
 
 
-def test_sanity_rgba(test_images):
+def test_sanity_rgba(test_images: Generator[Image.Image, None, None]) -> None:
     for im in test_images:
         roundtrip(im.convert("RGBA"))
 
 
-def test_sanity_l(test_images):
+def test_sanity_l(test_images: Generator[Image.Image, None, None]) -> None:
     for im in test_images:
         roundtrip(im.convert("L"))
 
 
-def test_sanity_p(test_images):
+def test_sanity_p(test_images: Generator[Image.Image, None, None]) -> None:
     for im in test_images:
         roundtrip(im.convert("P"))

Tests/test_image_getbands.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 from PIL import Image
 
 
-def test_getbands():
+def test_getbands() -> None:
     assert Image.new("1", (1, 1)).getbands() == ("1",)
     assert Image.new("L", (1, 1)).getbands() == ("L",)
     assert Image.new("I", (1, 1)).getbands() == ("I",)

Tests/test_image_getbbox.py

@@ -7,13 +7,13 @@ from PIL import Image
 from .helper import hopper
 
 
-def test_sanity():
+def test_sanity() -> None:
     bbox = hopper().getbbox()
     assert isinstance(bbox, tuple)
 
 
-def test_bbox():
+def test_bbox() -> None:
-    def check(im, fill_color):
+    def check(im: Image.Image, fill_color: int | tuple[int, ...]) -> None:
         assert im.getbbox() is None
 
         im.paste(fill_color, (10, 25, 90, 75))
@@ -34,8 +34,8 @@ def test_bbox():
     check(im, 255)
 
     for mode in ("RGBA", "RGBa"):
-        for color in ((0, 0, 0, 0), (127, 127, 127, 0), (255, 255, 255, 0)):
+        for rgba_color in ((0, 0, 0, 0), (127, 127, 127, 0), (255, 255, 255, 0)):
-            im = Image.new(mode, (100, 100), color)
+            im = Image.new(mode, (100, 100), rgba_color)
             check(im, (255, 255, 255, 255))
 
     for mode in ("La", "LA", "PA"):
@@ -45,7 +45,7 @@ def test_bbox():
 
 
 @pytest.mark.parametrize("mode", ("RGBA", "RGBa", "La", "LA", "PA"))
-def test_bbox_alpha_only_false(mode):
+def test_bbox_alpha_only_false(mode: str) -> None:
     im = Image.new(mode, (100, 100))
     assert im.getbbox(alpha_only=False) is None
 

Tests/test_image_getcolors.py

@@ -3,8 +3,8 @@ from __future__ import annotations
 from .helper import hopper
 
 
-def test_getcolors():
+def test_getcolors() -> None:
-    def getcolors(mode, limit=None):
+    def getcolors(mode: str, limit: int | None = None) -> int | None:
         im = hopper(mode)
         if limit:
             colors = im.getcolors(limit)
@@ -39,7 +39,7 @@ def test_getcolors():
 # --------------------------------------------------------------------
 
 
-def test_pack():
+def test_pack() -> None:
     # Pack problems for small tables (@PIL209)
 
     im = hopper().quantize(3).convert("RGB")

Tests/test_image_getdata.py

@@ -5,7 +5,7 @@ from PIL import Image
 from .helper import hopper
 
 
-def test_sanity():
+def test_sanity() -> None:
     data = hopper().getdata()
 
     len(data)
@@ -14,8 +14,8 @@ def test_sanity():
     assert data[0] == (20, 20, 70)
 
 
-def test_roundtrip():
+def test_roundtrip() -> None:
-    def getdata(mode):
+    def getdata(mode: str) -> tuple[float | tuple[int, ...], int, int]:
         im = hopper(mode).resize((32, 30), Image.Resampling.NEAREST)
         data = im.getdata()
         return data[0], len(data), len(list(data))

Tests/test_image_getim.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 from .helper import hopper
 
 
-def test_sanity():
+def test_sanity() -> None:
     im = hopper()
     type_repr = repr(type(im.getim()))
 

Tests/test_image_getprojection.py

@@ -5,7 +5,7 @@ from PIL import Image
 from .helper import hopper
 
 
-def test_sanity():
+def test_sanity() -> None:
     im = hopper()
 
     projection = im.getprojection()

Tests/test_image_histogram.py

@@ -3,8 +3,8 @@ from __future__ import annotations
 from .helper import hopper
 
 
-def test_histogram():
+def test_histogram() -> None:
-    def histogram(mode):
+    def histogram(mode: str) -> tuple[int, int, int]:
         h = hopper(mode).histogram()
         return len(h), min(h), max(h)
 

Tests/test_image_point.py

@@ -5,7 +5,7 @@ import pytest
 from .helper import assert_image_equal, hopper
 
 
-def test_sanity():
+def test_sanity() -> None:
     im = hopper()
 
     with pytest.raises(ValueError):
@@ -39,7 +39,7 @@ def test_sanity():
         im.point(lambda x: x // 2)
 
 
-def test_16bit_lut():
+def test_16bit_lut() -> None:
     """Tests for 16 bit -> 8 bit lut for converting I->L images
     see https://github.com/python-pillow/Pillow/issues/440
     """
@@ -47,7 +47,7 @@ def test_16bit_lut():
     im.point(list(range(256)) * 256, "L")
 
 
-def test_f_lut():
+def test_f_lut() -> None:
     """Tests for floating point lut of 8bit gray image"""
     im = hopper("L")
     lut = [0.5 * float(x) for x in range(256)]
@@ -58,7 +58,7 @@ def test_f_lut():
     assert_image_equal(out.convert("L"), im.point(int_lut, "L"))
 
 
-def test_f_mode():
+def test_f_mode() -> None:
     im = hopper("F")
     with pytest.raises(ValueError):
         im.point(None)

Tests/test_image_putalpha.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 from PIL import Image
 
 
-def test_interface():
+def test_interface() -> None:
     im = Image.new("RGBA", (1, 1), (1, 2, 3, 0))
     assert im.getpixel((0, 0)) == (1, 2, 3, 0)
 
@@ -17,7 +17,7 @@ def test_interface():
     assert im.getpixel((0, 0)) == (1, 2, 3, 5)
 
 
-def test_promote():
+def test_promote() -> None:
     im = Image.new("L", (1, 1), 1)
     assert im.getpixel((0, 0)) == 1
 
@@ -40,7 +40,7 @@ def test_promote():
     assert im.getpixel((0, 0)) == (1, 2, 3, 4)
 
 
-def test_readonly():
+def test_readonly() -> None:
     im = Image.new("RGB", (1, 1), (1, 2, 3))
     im.readonly = 1
 

Tests/test_image_quantize.py

@@ -8,7 +8,7 @@ from PIL import Image, features
 from .helper import assert_image_similar, hopper, is_ppc64le, skip_unless_feature
 
 
-def test_sanity():
+def test_sanity() -> None:
     image = hopper()
     converted = image.quantize()
     assert converted.mode == "P"
@@ -21,7 +21,7 @@ def test_sanity():
 
 
 @skip_unless_feature("libimagequant")
-def test_libimagequant_quantize():
+def test_libimagequant_quantize() -> None:
     image = hopper()
     if is_ppc64le():
         libimagequant = parse_version(features.version_feature("libimagequant"))
@@ -33,7 +33,7 @@ def test_libimagequant_quantize():
     assert len(converted.getcolors()) == 100
 
 
-def test_octree_quantize():
+def test_octree_quantize() -> None:
     image = hopper()
     converted = image.quantize(100, Image.Quantize.FASTOCTREE)
     assert converted.mode == "P"
@@ -41,7 +41,7 @@ def test_octree_quantize():
     assert len(converted.getcolors()) == 100
 
 
-def test_rgba_quantize():
+def test_rgba_quantize() -> None:
     image = hopper("RGBA")
     with pytest.raises(ValueError):
         image.quantize(method=0)
@@ -49,7 +49,7 @@ def test_rgba_quantize():
     assert image.quantize().convert().mode == "RGBA"
 
 
-def test_quantize():
+def test_quantize() -> None:
     with Image.open("Tests/images/caption_6_33_22.png") as image:
         image = image.convert("RGB")
     converted = image.quantize()
@@ -57,7 +57,7 @@ def test_quantize():
     assert_image_similar(converted.convert("RGB"), image, 1)
 
 
-def test_quantize_no_dither():
+def test_quantize_no_dither() -> None:
     image = hopper()
     with Image.open("Tests/images/caption_6_33_22.png") as palette:
         palette = palette.convert("P")
@@ -67,7 +67,7 @@ def test_quantize_no_dither():
     assert converted.palette.palette == palette.palette.palette
 
 
-def test_quantize_no_dither2():
+def test_quantize_no_dither2() -> None:
     im = Image.new("RGB", (9, 1))
     im.putdata([(p,) * 3 for p in range(0, 36, 4)])
 
@@ -83,7 +83,7 @@ def test_quantize_no_dither2():
         assert px[x, 0] == (0 if x < 5 else 1)
 
 
-def test_quantize_dither_diff():
+def test_quantize_dither_diff() -> None:
     image = hopper()
     with Image.open("Tests/images/caption_6_33_22.png") as palette:
         palette = palette.convert("P")
@@ -94,14 +94,14 @@ def test_quantize_dither_diff():
     assert dither.tobytes() != nodither.tobytes()
 
 
-def test_colors():
+def test_colors() -> None:
     im = hopper()
     colors = 2
     converted = im.quantize(colors)
     assert len(converted.palette.palette) == colors * len("RGB")
 
 
-def test_transparent_colors_equal():
+def test_transparent_colors_equal() -> None:
     im = Image.new("RGBA", (1, 2), (0, 0, 0, 0))
     px = im.load()
     px[0, 1] = (255, 255, 255, 0)
@@ -120,7 +120,7 @@ def test_transparent_colors_equal():
         (Image.Quantize.FASTOCTREE, (0, 0, 0, 0)),
     ),
 )
-def test_palette(method, color):
+def test_palette(method: Image.Quantize, color: tuple[int, ...]) -> None:
     im = Image.new("RGBA" if len(color) == 4 else "RGB", (1, 1), color)
 
     converted = im.quantize(method=method)
@@ -128,7 +128,7 @@ def test_palette(method, color):
     assert converted_px[0, 0] == converted.palette.colors[color]
 
 
-def test_small_palette():
+def test_small_palette() -> None:
     # Arrange
     im = hopper()
 

Tests/test_image_resize.py

@@ -4,6 +4,8 @@ Tests for resize functionality.
 from __future__ import annotations
 
 from itertools import permutations
+from pathlib import Path
+from typing import Generator
 
 import pytest
 
@@ -19,7 +21,9 @@ from .helper import (
 
 
 class TestImagingCoreResize:
-    def resize(self, im, size, f):
+    def resize(
+        self, im: Image.Image, size: tuple[int, int], f: Image.Resampling
+    ) -> Image.Image:
         # Image class independent version of resize.
         im.load()
         return im._new(im.im.resize(size, f))
@@ -27,14 +31,14 @@ class TestImagingCoreResize:
     @pytest.mark.parametrize(
         "mode", ("1", "P", "L", "I", "F", "RGB", "RGBA", "CMYK", "YCbCr", "I;16")
     )
-    def test_nearest_mode(self, mode):
+    def test_nearest_mode(self, mode: str) -> None:
         im = hopper(mode)
         r = self.resize(im, (15, 12), Image.Resampling.NEAREST)
         assert r.mode == mode
         assert r.size == (15, 12)
         assert r.im.bands == im.im.bands
 
-    def test_convolution_modes(self):
+    def test_convolution_modes(self) -> None:
         with pytest.raises(ValueError):
             self.resize(hopper("1"), (15, 12), Image.Resampling.BILINEAR)
         with pytest.raises(ValueError):
@@ -59,7 +63,7 @@ class TestImagingCoreResize:
             Image.Resampling.LANCZOS,
         ),
     )
-    def test_reduce_filters(self, resample):
+    def test_reduce_filters(self, resample: Image.Resampling) -> None:
         r = self.resize(hopper("RGB"), (15, 12), resample)
         assert r.mode == "RGB"
         assert r.size == (15, 12)
@@ -75,7 +79,7 @@ class TestImagingCoreResize:
             Image.Resampling.LANCZOS,
         ),
     )
-    def test_enlarge_filters(self, resample):
+    def test_enlarge_filters(self, resample: Image.Resampling) -> None:
         r = self.resize(hopper("RGB"), (212, 195), resample)
         assert r.mode == "RGB"
         assert r.size == (212, 195)
@@ -99,7 +103,9 @@ class TestImagingCoreResize:
             ("LA", ("filled", "dirty")),
         ),
     )
-    def test_endianness(self, resample, mode, channels_set):
+    def test_endianness(
+        self, resample: Image.Resampling, mode: str, channels_set: tuple[str, ...]
+    ) -> None:
         # Make an image with one colored pixel, in one channel.
         # When resized, that channel should be the same as a GS image.
         # Other channels should be unaffected.
@@ -139,17 +145,17 @@ class TestImagingCoreResize:
             Image.Resampling.LANCZOS,
         ),
     )
-    def test_enlarge_zero(self, resample):
+    def test_enlarge_zero(self, resample: Image.Resampling) -> None:
         r = self.resize(Image.new("RGB", (0, 0), "white"), (212, 195), resample)
         assert r.mode == "RGB"
         assert r.size == (212, 195)
         assert r.getdata()[0] == (0, 0, 0)
 
-    def test_unknown_filter(self):
+    def test_unknown_filter(self) -> None:
         with pytest.raises(ValueError):
             self.resize(hopper(), (10, 10), 9)
 
-    def test_cross_platform(self, tmp_path):
+    def test_cross_platform(self, tmp_path: Path) -> None:
         # This test is intended for only check for consistent behaviour across
         # platforms. So if a future Pillow change requires that the test file
         # be updated, that is okay.
@@ -162,7 +168,7 @@ class TestImagingCoreResize:
 
 
 @pytest.fixture
-def gradients_image():
+def gradients_image() -> Generator[Image.Image, None, None]:
     with Image.open("Tests/images/radial_gradients.png") as im:
         im.load()
     try:
@@ -172,7 +178,7 @@ def gradients_image():
 
 
 class TestReducingGapResize:
-    def test_reducing_gap_values(self, gradients_image):
+    def test_reducing_gap_values(self, gradients_image: Image.Image) -> None:
         ref = gradients_image.resize(
             (52, 34), Image.Resampling.BICUBIC, reducing_gap=None
         )
@@ -191,7 +197,12 @@ class TestReducingGapResize:
         "box, epsilon",
         ((None, 4), ((1.1, 2.2, 510.8, 510.9), 4), ((3, 10, 410, 256), 10)),
     )
-    def test_reducing_gap_1(self, gradients_image, box, epsilon):
+    def test_reducing_gap_1(
+        self,
+        gradients_image: Image.Image,
+        box: tuple[float, float, float, float],
+        epsilon: float,
+    ) -> None:
         ref = gradients_image.resize((52, 34), Image.Resampling.BICUBIC, box=box)
         im = gradients_image.resize(
             (52, 34), Image.Resampling.BICUBIC, box=box, reducing_gap=1.0
@@ -206,7 +217,12 @@ class TestReducingGapResize:
         "box, epsilon",
         ((None, 1.5), ((1.1, 2.2, 510.8, 510.9), 1.5), ((3, 10, 410, 256), 1)),
     )
-    def test_reducing_gap_2(self, gradients_image, box, epsilon):
+    def test_reducing_gap_2(
+        self,
+        gradients_image: Image.Image,
+        box: tuple[float, float, float, float],
+        epsilon: float,
+    ) -> None:
         ref = gradients_image.resize((52, 34), Image.Resampling.BICUBIC, box=box)
         im = gradients_image.resize(
             (52, 34), Image.Resampling.BICUBIC, box=box, reducing_gap=2.0
@@ -221,7 +237,12 @@ class TestReducingGapResize:
         "box, epsilon",
         ((None, 1), ((1.1, 2.2, 510.8, 510.9), 1), ((3, 10, 410, 256), 0.5)),
     )
-    def test_reducing_gap_3(self, gradients_image, box, epsilon):
+    def test_reducing_gap_3(
+        self,
+        gradients_image: Image.Image,
+        box: tuple[float, float, float, float],
+        epsilon: float,
+    ) -> None:
         ref = gradients_image.resize((52, 34), Image.Resampling.BICUBIC, box=box)
         im = gradients_image.resize(
             (52, 34), Image.Resampling.BICUBIC, box=box, reducing_gap=3.0
@@ -233,7 +254,9 @@ class TestReducingGapResize:
         assert_image_similar(ref, im, epsilon)
 
     @pytest.mark.parametrize("box", (None, (1.1, 2.2, 510.8, 510.9), (3, 10, 410, 256)))
-    def test_reducing_gap_8(self, gradients_image, box):
+    def test_reducing_gap_8(
+        self, gradients_image: Image.Image, box: tuple[float, float, float, float]
+    ) -> None:
         ref = gradients_image.resize((52, 34), Image.Resampling.BICUBIC, box=box)
         im = gradients_image.resize(
             (52, 34), Image.Resampling.BICUBIC, box=box, reducing_gap=8.0
@@ -245,7 +268,12 @@ class TestReducingGapResize:
         "box, epsilon",
         (((0, 0, 512, 512), 5.5), ((0.9, 1.7, 128, 128), 9.5)),
     )
-    def test_box_filter(self, gradients_image, box, epsilon):
+    def test_box_filter(
+        self,
+        gradients_image: Image.Image,
+        box: tuple[float, float, float, float],
+        epsilon: float,
+    ) -> None:
         ref = gradients_image.resize((52, 34), Image.Resampling.BOX, box=box)
         im = gradients_image.resize(
             (52, 34), Image.Resampling.BOX, box=box, reducing_gap=1.0
@@ -255,8 +283,8 @@ class TestReducingGapResize:
 
 
 class TestImageResize:
-    def test_resize(self):
+    def test_resize(self) -> None:
-        def resize(mode, size):
+        def resize(mode: str, size: tuple[int, int]) -> None:
             out = hopper(mode).resize(size)
             assert out.mode == mode
             assert out.size == size
@@ -271,7 +299,7 @@ class TestImageResize:
                 im.resize((10, 10), "unknown")
 
     @skip_unless_feature("libtiff")
-    def test_load_first(self):
+    def test_load_first(self) -> None:
         # load() may change the size of the image
         # Test that resize() is calling it before getting the size
         with Image.open("Tests/images/g4_orientation_5.tif") as im:
@@ -279,13 +307,13 @@ class TestImageResize:
             assert im.size == (64, 64)
 
     @pytest.mark.parametrize("mode", ("L", "RGB", "I", "F"))
-    def test_default_filter_bicubic(self, mode):
+    def test_default_filter_bicubic(self, mode: str) -> None:
         im = hopper(mode)
         assert im.resize((20, 20), Image.Resampling.BICUBIC) == im.resize((20, 20))
 
     @pytest.mark.parametrize(
         "mode", ("1", "P", "I;16", "I;16L", "I;16B", "BGR;15", "BGR;16")
     )
-    def test_default_filter_nearest(self, mode):
+    def test_default_filter_nearest(self, mode: str) -> None:
         im = hopper(mode)
         assert im.resize((20, 20), Image.Resampling.NEAREST) == im.resize((20, 20))

Tests/test_image_split.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from pathlib import Path
+
 import pytest
 
 from PIL import Image, features
@@ -7,8 +9,8 @@ from PIL import Image, features
 from .helper import assert_image_equal, hopper
 
 
-def test_split():
+def test_split() -> None:
-    def split(mode):
+    def split(mode: str) -> list[tuple[str, int, int]]:
         layers = hopper(mode).split()
         return [(i.mode, i.size[0], i.size[1]) for i in layers]
 
@@ -36,18 +38,18 @@ def test_split():
 @pytest.mark.parametrize(
     "mode", ("1", "L", "I", "F", "P", "RGB", "RGBA", "CMYK", "YCbCr")
 )
-def test_split_merge(mode):
+def test_split_merge(mode: str) -> None:
     expected = Image.merge(mode, hopper(mode).split())
     assert_image_equal(hopper(mode), expected)
 
 
-def test_split_open(tmp_path):
+def test_split_open(tmp_path: Path) -> None:
     if features.check("zlib"):
         test_file = str(tmp_path / "temp.png")
     else:
         test_file = str(tmp_path / "temp.pcx")
 
-    def split_open(mode):
+    def split_open(mode: str) -> int:
         hopper(mode).save(test_file)
         with Image.open(test_file) as im:
             return len(im.split())

Tests/test_image_tobitmap.py

@@ -5,7 +5,7 @@ import pytest
 from .helper import assert_image_equal, fromstring, hopper
 
 
-def test_sanity():
+def test_sanity() -> None:
     with pytest.raises(ValueError):
         hopper().tobitmap()
 

Tests/test_image_tobytes.py

@@ -3,6 +3,6 @@ from __future__ import annotations
 from .helper import hopper
 
 
-def test_sanity():
+def test_sanity() -> None:
     data = hopper().tobytes()
     assert isinstance(data, bytes)

Tests/test_image_transpose.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import pytest
 
+from PIL import Image
 from PIL.Image import Transpose
 
 from . import helper
@@ -14,7 +15,7 @@ HOPPER = {
 
 
 @pytest.mark.parametrize("mode", HOPPER)
-def test_flip_left_right(mode):
+def test_flip_left_right(mode: str) -> None:
     im = HOPPER[mode]
     out = im.transpose(Transpose.FLIP_LEFT_RIGHT)
     assert out.mode == mode
@@ -28,7 +29,7 @@ def test_flip_left_right(mode):
 
 
 @pytest.mark.parametrize("mode", HOPPER)
-def test_flip_top_bottom(mode):
+def test_flip_top_bottom(mode: str) -> None:
     im = HOPPER[mode]
     out = im.transpose(Transpose.FLIP_TOP_BOTTOM)
     assert out.mode == mode
@@ -42,7 +43,7 @@ def test_flip_top_bottom(mode):
 
 
 @pytest.mark.parametrize("mode", HOPPER)
-def test_rotate_90(mode):
+def test_rotate_90(mode: str) -> None:
     im = HOPPER[mode]
     out = im.transpose(Transpose.ROTATE_90)
     assert out.mode == mode
@@ -56,7 +57,7 @@ def test_rotate_90(mode):
 
 
 @pytest.mark.parametrize("mode", HOPPER)
-def test_rotate_180(mode):
+def test_rotate_180(mode: str) -> None:
     im = HOPPER[mode]
     out = im.transpose(Transpose.ROTATE_180)
     assert out.mode == mode
@@ -70,7 +71,7 @@ def test_rotate_180(mode):
 
 
 @pytest.mark.parametrize("mode", HOPPER)
-def test_rotate_270(mode):
+def test_rotate_270(mode: str) -> None:
     im = HOPPER[mode]
     out = im.transpose(Transpose.ROTATE_270)
     assert out.mode == mode
@@ -84,7 +85,7 @@ def test_rotate_270(mode):
 
 
 @pytest.mark.parametrize("mode", HOPPER)
-def test_transpose(mode):
+def test_transpose(mode: str) -> None:
     im = HOPPER[mode]
     out = im.transpose(Transpose.TRANSPOSE)
     assert out.mode == mode
@@ -98,7 +99,7 @@ def test_transpose(mode):
 
 
 @pytest.mark.parametrize("mode", HOPPER)
-def test_tranverse(mode):
+def test_tranverse(mode: str) -> None:
     im = HOPPER[mode]
     out = im.transpose(Transpose.TRANSVERSE)
     assert out.mode == mode
@@ -112,10 +113,10 @@ def test_tranverse(mode):
 
 
 @pytest.mark.parametrize("mode", HOPPER)
-def test_roundtrip(mode):
+def test_roundtrip(mode: str) -> None:
     im = HOPPER[mode]
 
-    def transpose(first, second):
+    def transpose(first: Transpose, second: Transpose) -> Image.Image:
         return im.transpose(first).transpose(second)
 
     assert_image_equal(