Assert image type

Tests/test_file_iptc.py

@@ -143,6 +143,7 @@ def test_getiptcinfo_tiff() -> None:
 
     # Test with LONG tag type
     with Image.open("Tests/images/hopper.Lab.tif") as im:
+        assert isinstance(im, TiffImagePlugin.TiffImageFile)
         im.tag_v2.tagtype[TiffImagePlugin.IPTC_NAA_CHUNK] = TiffTags.LONG
         iptc = IptcImagePlugin.getiptcinfo(im)
 

Tests/test_file_libtiff.py

@@ -378,6 +378,7 @@ class TestFileLibTiff(LibTiffTestCase):
         im.save(out, tiffinfo=ifd)
 
         with Image.open(out) as reloaded:
+            assert isinstance(reloaded, TiffImagePlugin.TiffImageFile)
             assert reloaded.tag_v2[37000] == 100
 
     def test_inknames_tag(

Tests/test_file_png.py

@@ -787,7 +787,9 @@ class TestFilePng:
             im.save(test_file, exif=im.getexif())
 
         with Image.open(test_file) as reloaded:
+            assert isinstance(reloaded, PngImagePlugin.PngImageFile)
             exif = reloaded._getexif()
+        assert exif is not None
         assert exif[305] == "Adobe Photoshop CS Macintosh"
 
     def test_exif_argument(self, tmp_path: Path) -> None:

src/PIL/Image.py

@@ -1519,6 +1519,9 @@ class Image:
                     "".join(self.info["Raw profile type exif"].split("\n")[3:])
                 )
             elif hasattr(self, "tag_v2"):
+                from . import TiffImagePlugin
+
+                assert isinstance(self, TiffImagePlugin.TiffImageFile)
                 self._exif.bigtiff = self.tag_v2._bigtiff
                 self._exif.endian = self.tag_v2._endian
                 self._exif.load_from_fp(self.fp, self.tag_v2._offset)