  We present pytest-inline, the first inline testing framework for Python. We
recently proposed inline tests to make it easier to test individual program
statements. But, there is no framework-level support for developers to write
inline tests in Python. To fill this gap, we design and implement pytest-inline
as a plugin for pytest, the most popular Python testing framework. Using
pytest-inline, a developer can write an inline test by assigning test inputs to
variables in a target statement and specifying the expected test output. Then,
pytest-inline runs each inline test and fails if the target statement's output
does not match the expected output. In this paper, we describe our design of
pytest-inline, the testing features that it provides, and the intended use
cases. Our evaluation on inline tests that we wrote for 80 target statements
from 31 open-source Python projects shows that using pytest-inline incurs
negligible overhead, at 0.012x. pytest-inline is integrated into the pytest-dev
organization, and a video demo is at
https://www.youtube.com/watch?v=pZgiAxR_uJg.
