TST: method-specific files for DataFrame assign, interpolate 
thanks, comment from tests-series-interpolate PR, more interpolate tests in pandas/tests/generic on this genre of PRs (i.e. "method-specific file for X") are you OK with having Will and Simon review+merge?  Could ease some of the backlog > on this genre of PRs (i.e. "method-specific file for X") are you OK with having Will and Simon review+merge? Could ease some of the backlog

absolutely!