Minimal test for typeshed reportlab issue

gistfile1.txt

$ python minimal_test.py
Test passed successfully
$ mypy minimal_test.py  
minimal_test.py:13: error: Argument "filename" to "build" of "BaseDocTemplate" has incompatible type "BytesIO"; expected "str | None"  [arg-type]
Found 1 error in 1 file (checked 1 source file)h

minimal_test.py

import io
from pathlib import Path
from reportlab.platypus import BaseDocTemplate, PageTemplate, Frame, Paragraph
from reportlab.lib.units import inch

Path('test.pdf').unlink(True)
Path('not_test.pdf').unlink(True)

frame = Frame(2*inch, 2*inch, 5*inch, 5*inch)
template = PageTemplate(frames=[frame])
doc = BaseDocTemplate("test.pdf", pageTemplates=[template])
with io.BytesIO() as buffer:
    doc.build([Paragraph("hello world")], filename=buffer)

    with open("not_test.pdf", "wb") as f:
        f.write(buffer.getvalue())

# PDF written to not_test.pdf

assert not Path('test.pdf').exists(), "test.pdf should not be created"
assert Path('not_test.pdf').exists(), "not_test.pdf should be created"

Path('test.pdf').unlink(True)
Path('not_test.pdf').unlink(True)

print("Test passed successfully")