Assert image type

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)
@@ -230,38 +250,44 @@ 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)
 
     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)
 
     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")
@@ -271,44 +297,53 @@ def test_apng_mode() -> None:
 
 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
     exception = None
     with Image.open("Tests/images/apng/syntax_num_frames_low.png") as im:
+        assert isinstance(im, PngImagePlugin.PngImageFile)
         try:
             im.seek(im.n_frames - 1)
         except Exception as e:
@@ -317,11 +352,13 @@ def test_apng_syntax_errors() -> None:
 
     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()
 
@@ -341,6 +378,7 @@ 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()
 
@@ -351,6 +389,7 @@ 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
@@ -366,6 +405,7 @@ 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
@@ -405,6 +445,7 @@ 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)
         exception = None
         try:
             im.seek(im.n_frames - 1)
@@ -452,6 +493,7 @@ 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
 
@@ -473,6 +515,7 @@ 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_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_eps.py

@@ -86,6 +86,8 @@
 def test_sanity(filename: str, size: tuple[int, int], scale: int) -> None:
     expected_size = tuple(s * scale for s in size)
     with Image.open(filename) as image:
+        assert isinstance(image, EpsImagePlugin.EpsImageFile)
+
         image.load(scale=scale)
         assert image.mode == "RGB"
         assert image.size == expected_size
@@ -223,6 +225,8 @@ def test_showpage() -> None:
 @pytest.mark.skipif(not HAS_GHOSTSCRIPT, reason="Ghostscript not available")
 def test_transparency() -> None:
     with Image.open("Tests/images/eps/reqd_showpage.eps") as plot_image:
+        assert isinstance(plot_image, EpsImagePlugin.EpsImageFile)
+
         plot_image.load(transparency=True)
         assert plot_image.mode == "RGBA"
 
@@ -304,6 +308,7 @@ def test_render_scale2() -> None:
 
     # Zero bounding box
     with Image.open(FILE1) as image1_scale2:
+        assert isinstance(image1_scale2, EpsImagePlugin.EpsImageFile)
         image1_scale2.load(scale=2)
         with Image.open(FILE1_COMPARE_SCALE2) as image1_scale2_compare:
             image1_scale2_compare = image1_scale2_compare.convert("RGB")
@@ -312,6 +317,7 @@ def test_render_scale2() -> None:
 
     # Non-zero bounding box
     with Image.open(FILE2) as image2_scale2:
+        assert isinstance(image2_scale2, EpsImagePlugin.EpsImageFile)
         image2_scale2.load(scale=2)
         with Image.open(FILE2_COMPARE_SCALE2) as image2_scale2_compare:
             image2_scale2_compare = image2_scale2_compare.convert("RGB")

Tests/test_file_fpx.py

@@ -22,10 +22,11 @@ def test_sanity() -> None:
 
 def test_close() -> None:
     with Image.open("Tests/images/input_bw_one_band.fpx") as im:
-        pass
+        assert isinstance(im, FpxImagePlugin.FpxImageFile)
     assert im.ole.fp.closed
 
     im = Image.open("Tests/images/input_bw_one_band.fpx")
+    assert isinstance(im, FpxImagePlugin.FpxImageFile)
     im.close()
     assert im.ole.fp.closed
 

Tests/test_file_icns.py

@@ -65,6 +65,7 @@ def test_save_append_images(tmp_path: Path) -> None:
         assert_image_similar_tofile(im, temp_file, 1)
 
         with Image.open(temp_file) as reread:
+            assert isinstance(reread, IcnsImagePlugin.IcnsImageFile)
             reread.size = (16, 16)
             reread.load(2)
             assert_image_equal(reread, provided_im)
@@ -86,6 +87,7 @@ def test_sizes() -> None:
     # Check that we can load all of the sizes, and that the final pixel
     # dimensions are as expected
     with Image.open(TEST_FILE) as im:
+        assert isinstance(im, IcnsImagePlugin.IcnsImageFile)
         for w, h, r in im.info["sizes"]:
             wr = w * r
             hr = h * r
@@ -114,6 +116,7 @@ def test_older_icon() -> None:
             wr = w * r
             hr = h * r
             with Image.open("Tests/images/pillow2.icns") as im2:
+                assert isinstance(im2, IcnsImagePlugin.IcnsImageFile)
                 im2.size = (w, h)
                 im2.load(r)
                 assert im2.mode == "RGBA"
@@ -131,6 +134,7 @@ def test_jp2_icon() -> None:
             wr = w * r
             hr = h * r
             with Image.open("Tests/images/pillow3.icns") as im2:
+                assert isinstance(im2, IcnsImagePlugin.IcnsImageFile)
                 im2.size = (w, h)
                 im2.load(r)
                 assert im2.mode == "RGBA"