Do not compare properties to themselves

[radarhere]

The assert_image helper method is useful to assert an image's mode and size.

Pillow/Tests/helper.py

Lines 77 to 86 in 9d0703a

	def assert_image(im, mode, size, msg=None):
	if mode is not None:
	assert im.mode == mode, (
	msg or f"got mode {repr(im.mode)}, expected {repr(mode)}"
	)
	if size is not None:
	assert im.size == size, (
	msg or f"got size {repr(im.size)}, expected {repr(size)}"
	)

However, I think that

assert_image(im, "P", im.size)

could be more clearly expressed as

assert im.mode == "P"

Similarly,

assert_image(im, im.mode, (40, 60))

should be changed to

assert im.size == (40, 60)

And

assert_image(im, im.mode, im.size)

seems redundant.