Fix race condition in NetworkWatchListTest
We were running cp to create a file and then running a command to read
the file. However were weren't waiting for the cp to finish (or,
indeed, start), so occasionally the read would fail saying the file
didn't exist.
Also added some logging, because diagnosing failure without it is
painful. Also simplify & improve file closing logic.
Some of this was previously submitted on internal master as change
I1c875102f0cce32cbbe2e3b36de913741c9abb92, but I've reverted that in
favor of this.
Bug: 168216494
Test: atest CtsNetTestCases:android.net.cts.NetworkWatchlistTest
Change-Id: I46a9db8b7a1885a9829f00bbd3233b863cfd1f5d
1 file changed
