Added type hints

Tests/helper.py

@@ -97,6 +97,7 @@ def assert_image_equal(a: Image.Image, b: Image.Image, msg: str | None = None) -
 def assert_image_equal_tofile(
     a: Image.Image, filename: str, msg: str | None = None, mode: str | None = None
 ) -> None:
+    img: Image.Image
     with Image.open(filename) as img:
         if mode:
             img = img.convert(mode)
@@ -140,6 +141,7 @@ def assert_image_similar_tofile(
     epsilon: float,
     msg: str | None = None,
 ) -> None:
+    img: Image.Image
     with Image.open(filename) as img:
         assert_image_similar(a, img, epsilon, msg)
 

Tests/test_bmp_reference.py

@@ -94,8 +94,11 @@ def get_compare(f: str) -> str:
 
     for f in get_files("g"):
         try:
+            im: Image.Image
             with Image.open(f) as im:
                 im.load()
+
+                compare: Image.Image
                 with Image.open(get_compare(f)) as compare:
                     compare.load()
                     if im.mode == "P":

Tests/test_file_apng.py

@@ -12,6 +12,7 @@
 # (referenced from https://wiki.mozilla.org/APNG_Specification)
 def test_apng_basic() -> None:
     with Image.open("Tests/images/apng/single_frame.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert not im.is_animated
         assert im.n_frames == 1
         assert im.get_format_mimetype() == "image/apng"
@@ -20,6 +21,7 @@ def test_apng_basic() -> None:
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
 
     with Image.open("Tests/images/apng/single_frame_default.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert im.is_animated
         assert im.n_frames == 2
         assert im.get_format_mimetype() == "image/apng"
@@ -49,60 +51,71 @@ def test_apng_basic() -> None:
 )
 def test_apng_fdat(filename: str) -> None:
     with Image.open(filename) as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 255)
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
 
 
 def test_apng_dispose() -> None:
     with Image.open("Tests/images/apng/dispose_op_none.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 255)
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
 
     with Image.open("Tests/images/apng/dispose_op_background.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 0, 0, 0)
         assert im.getpixel((64, 32)) == (0, 0, 0, 0)
 
     with Image.open("Tests/images/apng/dispose_op_background_final.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 255)
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
 
     with Image.open("Tests/images/apng/dispose_op_previous.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 255)
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
 
     with Image.open("Tests/images/apng/dispose_op_previous_final.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 255)
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
 
     with Image.open("Tests/images/apng/dispose_op_previous_first.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 0, 0, 0)
         assert im.getpixel((64, 32)) == (0, 0, 0, 0)
 
 
 def test_apng_dispose_region() -> None:
     with Image.open("Tests/images/apng/dispose_op_none_region.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 255)
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
 
     with Image.open("Tests/images/apng/dispose_op_background_before_region.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 0, 0, 0)
         assert im.getpixel((64, 32)) == (0, 0, 0, 0)
 
     with Image.open("Tests/images/apng/dispose_op_background_region.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 0, 255, 255)
         assert im.getpixel((64, 32)) == (0, 0, 0, 0)
 
     with Image.open("Tests/images/apng/dispose_op_previous_region.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 255)
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
@@ -129,6 +142,7 @@ def test_apng_dispose_op_previous_frame() -> None:
     #     ],
     # )
     with Image.open("Tests/images/apng/dispose_op_previous_frame.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (255, 0, 0, 255)
 
@@ -142,26 +156,31 @@ def test_apng_dispose_op_background_p_mode() -> None:
 
 def test_apng_blend() -> None:
     with Image.open("Tests/images/apng/blend_op_source_solid.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 255)
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
 
     with Image.open("Tests/images/apng/blend_op_source_transparent.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 0, 0, 0)
         assert im.getpixel((64, 32)) == (0, 0, 0, 0)
 
     with Image.open("Tests/images/apng/blend_op_source_near_transparent.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 2)
         assert im.getpixel((64, 32)) == (0, 255, 0, 2)
 
     with Image.open("Tests/images/apng/blend_op_over.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 255)
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
 
     with Image.open("Tests/images/apng/blend_op_over_near_transparent.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 97)
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
@@ -175,6 +194,7 @@ def test_apng_blend_transparency() -> None:
 
 def test_apng_chunk_order() -> None:
     with Image.open("Tests/images/apng/fctl_actl.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 255, 0, 255)
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
@@ -230,93 +250,110 @@ def test_apng_num_plays() -> None:
 
 def test_apng_mode() -> None:
     with Image.open("Tests/images/apng/mode_16bit.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert im.mode == "RGBA"
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (0, 0, 128, 191)
         assert im.getpixel((64, 32)) == (0, 0, 128, 191)
 
     with Image.open("Tests/images/apng/mode_grayscale.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert im.mode == "L"
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == 128
         assert im.getpixel((64, 32)) == 255
 
     with Image.open("Tests/images/apng/mode_grayscale_alpha.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert im.mode == "LA"
         im.seek(im.n_frames - 1)
         assert im.getpixel((0, 0)) == (128, 191)
         assert im.getpixel((64, 32)) == (128, 191)
 
     with Image.open("Tests/images/apng/mode_palette.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert im.mode == "P"
         im.seek(im.n_frames - 1)
-        im = im.convert("RGB")
-        assert im.getpixel((0, 0)) == (0, 255, 0)
-        assert im.getpixel((64, 32)) == (0, 255, 0)
+        rgb_im = im.convert("RGB")
+        assert rgb_im.getpixel((0, 0)) == (0, 255, 0)
+        assert rgb_im.getpixel((64, 32)) == (0, 255, 0)
 
     with Image.open("Tests/images/apng/mode_palette_alpha.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert im.mode == "P"
         im.seek(im.n_frames - 1)
-        im = im.convert("RGBA")
-        assert im.getpixel((0, 0)) == (0, 255, 0, 255)
-        assert im.getpixel((64, 32)) == (0, 255, 0, 255)
+        rgb_im = im.convert("RGBA")
+        assert rgb_im.getpixel((0, 0)) == (0, 255, 0, 255)
+        assert rgb_im.getpixel((64, 32)) == (0, 255, 0, 255)
 
     with Image.open("Tests/images/apng/mode_palette_1bit_alpha.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert im.mode == "P"
         im.seek(im.n_frames - 1)
-        im = im.convert("RGBA")
-        assert im.getpixel((0, 0)) == (0, 0, 255, 128)
-        assert im.getpixel((64, 32)) == (0, 0, 255, 128)
+        rgb_im = im.convert("RGBA")
+        assert rgb_im.getpixel((0, 0)) == (0, 0, 255, 128)
+        assert rgb_im.getpixel((64, 32)) == (0, 0, 255, 128)
 
 
 def test_apng_chunk_errors() -> None:
     with Image.open("Tests/images/apng/chunk_no_actl.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert not im.is_animated
 
     with pytest.warns(UserWarning):
         with Image.open("Tests/images/apng/chunk_multi_actl.png") as im:
             im.load()
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert not im.is_animated
 
     with Image.open("Tests/images/apng/chunk_actl_after_idat.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert not im.is_animated
 
     with Image.open("Tests/images/apng/chunk_no_fctl.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         with pytest.raises(SyntaxError):
             im.seek(im.n_frames - 1)
 
     with Image.open("Tests/images/apng/chunk_repeat_fctl.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         with pytest.raises(SyntaxError):
             im.seek(im.n_frames - 1)
 
     with Image.open("Tests/images/apng/chunk_no_fdat.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         with pytest.raises(SyntaxError):
             im.seek(im.n_frames - 1)
 
 
 def test_apng_syntax_errors() -> None:
     with pytest.warns(UserWarning):
         with Image.open("Tests/images/apng/syntax_num_frames_zero.png") as im:
+            assert isinstance(im, PngImagePlugin.PngImageFile)
             assert not im.is_animated
             with pytest.raises(OSError):
                 im.load()
 
     with pytest.warns(UserWarning):
         with Image.open("Tests/images/apng/syntax_num_frames_zero_default.png") as im:
+            assert isinstance(im, PngImagePlugin.PngImageFile)
             assert not im.is_animated
             im.load()
 
     # we can handle this case gracefully
     with Image.open("Tests/images/apng/syntax_num_frames_low.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
 
     with pytest.raises(OSError):
         with Image.open("Tests/images/apng/syntax_num_frames_high.png") as im:
+            assert isinstance(im, PngImagePlugin.PngImageFile)
             im.seek(im.n_frames - 1)
             im.load()
 
     with pytest.warns(UserWarning):
         with Image.open("Tests/images/apng/syntax_num_frames_invalid.png") as im:
+            assert isinstance(im, PngImagePlugin.PngImageFile)
             assert not im.is_animated
             im.load()
 
@@ -336,6 +373,7 @@ def test_apng_syntax_errors() -> None:
 def test_apng_sequence_errors(test_file: str) -> None:
     with pytest.raises(SyntaxError):
         with Image.open(f"Tests/images/apng/{test_file}") as im:
+            assert isinstance(im, PngImagePlugin.PngImageFile)
             im.seek(im.n_frames - 1)
             im.load()
 
@@ -346,6 +384,8 @@ def test_apng_save(tmp_path: Path) -> None:
         im.save(test_file, save_all=True)
 
     with Image.open(test_file) as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
+
         im.load()
         assert not im.is_animated
         assert im.n_frames == 1
@@ -361,6 +401,8 @@ def test_apng_save(tmp_path: Path) -> None:
         )
 
     with Image.open(test_file) as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
+
         im.load()
         assert im.is_animated
         assert im.n_frames == 2
@@ -400,6 +442,7 @@ def test_apng_save_split_fdat(tmp_path: Path) -> None:
             append_images=frames,
         )
     with Image.open(test_file) as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         im.seek(im.n_frames - 1)
         im.load()
 
@@ -442,6 +485,7 @@ def test_apng_save_duration_loop(tmp_path: Path) -> None:
         test_file, save_all=True, append_images=[frame, frame], duration=[500, 100, 150]
     )
     with Image.open(test_file) as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert im.n_frames == 1
         assert "duration" not in im.info
 
@@ -453,6 +497,7 @@ def test_apng_save_duration_loop(tmp_path: Path) -> None:
         duration=[500, 100, 150],
     )
     with Image.open(test_file) as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert im.n_frames == 2
         assert im.info["duration"] == 600
 
@@ -463,6 +508,7 @@ def test_apng_save_duration_loop(tmp_path: Path) -> None:
     frame.info["duration"] = 300
     frame.save(test_file, save_all=True, append_images=[frame, different_frame])
     with Image.open(test_file) as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         assert im.n_frames == 2
         assert im.info["duration"] == 600
 

Tests/test_file_bmp.py

@@ -166,9 +166,9 @@ def test_save_dib(tmp_path: Path) -> None:
 def test_rgba_bitfields() -> None:
     # This test image has been manually hexedited
     # to change the bitfield compression in the header from XBGR to RGBA
-    with Image.open("Tests/images/rgb32bf-rgba.bmp") as im:
+    with Image.open("Tests/images/rgb32bf-rgba.bmp") as bmp_im:
         # So before the comparing the image, swap the channels
-        b, g, r = im.split()[1:]
+        b, g, r = bmp_im.split()[1:]
         im = Image.merge("RGB", (r, g, b))
 
     assert_image_equal_tofile(im, "Tests/images/bmp/q/rgb32bf-xbgr.bmp")

Tests/test_file_bufrstub.py

@@ -61,6 +61,7 @@ def open(self, im: ImageFile.StubImageFile) -> None:
 
         def load(self, im: ImageFile.StubImageFile) -> Image.Image:
             self.loaded = True
+            assert im.fp is not None
             im.fp.close()
             return Image.new("RGB", (1, 1))
 

Tests/test_file_cur.py

@@ -26,6 +26,7 @@ def test_invalid_file() -> None:
     no_cursors_file = "Tests/images/no_cursors.cur"
 
     cur = CurImagePlugin.CurImageFile(TEST_FILE)
+    assert cur.fp is not None
     cur.fp.close()
     with open(no_cursors_file, "rb") as cur.fp:
         with pytest.raises(TypeError):

Tests/test_file_dcx.py

@@ -69,12 +69,14 @@ def test_tell() -> None:
 
 def test_n_frames() -> None:
     with Image.open(TEST_FILE) as im:
+        assert isinstance(im, DcxImagePlugin.DcxImageFile)
         assert im.n_frames == 1
         assert not im.is_animated
 
 
 def test_eoferror() -> None:
     with Image.open(TEST_FILE) as im:
+        assert isinstance(im, DcxImagePlugin.DcxImageFile)
         n_frames = im.n_frames
 
         # Test seeking past the last frame

Tests/test_file_dds.py

@@ -50,6 +50,7 @@
 )
 def test_sanity_dxt1_bc1(image_path: str) -> None:
     """Check DXT1 and BC1 images can be opened"""
+    target: Image.Image
     with Image.open(TEST_FILE_DXT1.replace(".dds", ".png")) as target:
         target = target.convert("RGBA")
     with Image.open(image_path) as im: