Currently, running `test.py --build` will attempt to build
the necessary files, before running the tests specified.
However, the tests are run even if this build fails, which
usually means old build artefacts are used for running the tests.
This can lead to some very confusing results if you do not yourself
catch that the build failed half-way through the run.
This change makes `test.py` exit with an error code and a message,
and does not proceed with the tests, if the build fails.
TEST=Manual testing locally.
Change-Id: I4e0f1d3f8d695219f2e4c0d7b474542af136aca9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/241740
Reviewed-by: William Hesse <whesse@google.com>
Commit-Queue: Clement Skau <cskau@google.com>
Clement Skau
1320e644d5