[Python] How to create and write to a textiowrapper and readlines

So I am trying to create a text io wrapper that I can then use readlines() from for a unittest. Here is my attempt, but when I run it the readlines() returns nothing:

output = io.BytesIO()
wrapper = io.TextIOWrapper(
output,
encoding='cp1252',
line_buffering=True,
)

wrapper.write('Text1')
wrapper.write('Text2')
wrapper.write('Text3')
wrapper.write('Text4')

for line in wrapper.readlines():
print(line)


What do I need to change to get this output:

Text1
Text2
Text3
Text4

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