Redmine

The attached patch adds a section to doc/RUNNING_TESTS that describes how to make the Mercurial tests much faster by using chg.

Unlike the commands of other SCMs such as Git and Subversion, the hg command is slow to start because it has to start the Python interpreter every time it is invoked. On my macOS machine, git --version takes about 0.01 seconds and svn --version about 0.06 seconds, while hg --version takes about 0.2 seconds. Since the Mercurial tests invoke hg 470 times, most of their run time is spent on starting the command.

chg is a client for the Mercurial command server and avoids this startup cost. To use it, set scm_mercurial_command in config/configuration.yml:

test:
  scm_mercurial_command: chg

I measured the run time of the following three Mercurial test files (98 tests in total) with hg and with chg:

• test/unit/lib/redmine/scm/adapters/mercurial_adapter_test.rb
• test/unit/repository_mercurial_test.rb
• test/functional/repositories_mercurial_controller_test.rb

All tests passed in both cases.

The patch changes only the documentation.