This is a test, this is only a test:
most difficult
bullet: •
ellipsis: ⋯
smiley: ☺ @ 0x263a
white king: ♔
<=: ≤
letters
c cedilla: ç
cyrillic small letter ia: я
hebrew letter bet: ב
beta: β
latin small letter sharp s: ß
latin small letter thorn: þ
ligatures oe, then ae: œuf Œ æsthetic Æ
scandinavian vowels: å mÖØse
symbols
cjk, ideographs, etc.: 逸 逹 @ 0x9038—0x9039, ぴ @ 0x3074
copyright: ©
half-sign: ½
pounds sterling: £
euro: ₠ @ 0x20a0, € @ 0x20ac
registered: ®
section mark: §
trademark: ™
w cubed: w³ (0xb3) w (0x2073)