PR12926 backport https://github.com/bitcoin/bitcoin/pull/12926/files
7ef9cd8 Increase entropy in test temp directory name (Pieter Wuille)
f6dfb0f Reorder travis builds (Pieter Wuille)
156db42 tests: run tests in parallel (Cory Fields)
66f3255 tests: split up actual tests and helper files (Cory Fields)
Pull request description:
This runs the unit tests (`src/test/test_bitcoin`) in 4 separate simultaneous processes, significantly speeding up some Travis runs (over 2x for win32). This uses an approach by @theuni that relies on `make` as the mechanism for distributing tests over processes (through `-j`). For every test .cpp file, we search for `BOOST_FIXTURE_TEST_SUITE` or `BOOST_AUTO_TEST_SUITE`, and then invoke the test binary for just that suite (using `-t`). The (verbose) output is stored in a temporary file, and only shown in the case of failure. Some makefile reshuffling is necessary to avoid trying to run tests from `src/test/test_bitcoin.cpp` for example, which contains framework/utility code but no real tests. Finally, order the Travis jobs from slow to fast (apart from the arm/doc job which goes first, for fast failure). This should help reducing the total wall clock time before opening a PR and finishing Travis, in case where not all jobs are started simultaneously. This is an alternative to #12831.