Prevent cylc-run of creating directories for invalid suites

[kinow]

These changes close #3097

Requirements check-list

• I have read CONTRIBUTING.md and added my name as a Code Contributor.
• Contains logically grouped changes (else tidy your branch by rebase).
• Does not contain off-topic changes (use other PRs for other changes).
• Appropriate tests are included (unit and/or functional).
• Appropriate change log entry included.
• No documentation update required.

[kinow]

Shamelessly copied this approach from cylc-cat-log.

[kinow]

New behaviour:

$ cylc run mp3
suite service directory not found at: /home/kinow/cylc-run/mp3/.service

Tested cylc-register and it appears to be working fine. I think the code changed is not used by cylc-register.

[hjoliver]

One test failed, probably real, or else a huge coincidence!

./flakytests/registration/02-on-the-fly.t              (Wstat: 0 Tests: 9 Failed: 3)

[kinow]

One test failed, probably real, or else a huge coincidence!

./flakytests/registration/02-on-the-fly.t              (Wstat: 0 Tests: 9 Failed: 3)

Kicked Travis as it was one of the flakytests 🤞

[hjoliver]

I predict it'll fail again 😬 :

$ ./etc/bin/run-functional-tests.sh -v flakytests/registration/02-on-the-fly.t 

ok 1 - 02-on-the-fly-pwd-run
ok 2 - 02-on-the-fly-pwd-run.stdout-contains-ok
ok 3 - 02-on-the-fly-pwd-stop
not ok 4 - 02-on-the-fly-cylc-run-dir-run
not ok 5 - 02-on-the-fly-cylc-run-dir-run.stdout-contains-ok
not ok 6 - 02-on-the-fly-cylc-run-dir-stop
ok 7 - 02-on-the-fly-cylc-run-dir-2-validate
ok 8 - 02-on-the-fly-cylc-run-dir-2-validate.stdout-contains-ok
ok 9 - 02-on-the-fly-cylc-run-dir-2-validate.stderr-contains-ok

    stdout and stderr stored in: /tmp/oliverh/cylctb-20191014T090638Z/registration/02-on-the-fly
Failed 3/9 subtests 
[22:06:53]

Test Summary Report
-------------------
flakytests/registration/02-on-the-fly.t (Wstat: 0 Tests: 9 Failed: 3)
  Failed tests:  4-6
Files=1, Tests=9, 15 wallclock secs ( 0.02 usr  0.00 sys +  2.04 cusr  0.40 csys =  2.46 CPU)
Result: FAIL

[kinow]

Was re-creating my virtual env to run it, but you beat me to it. Let me take a look at the code. Thanks!

[kinow]

Take 2. The code was checking for ~/cylc-run/blabla/.service, which prevented the on-the-fly registration. I updated the code to now use get_suite_run_dir, and then test for ~/cylc-run/blabla.

Wondering if this is good enough, or if we must prevent the cylc run of running if:

• no suite.rc or
• no .service dir as before ?

[hjoliver]

Seems to have the desired behaviour, for normal run and on-the-fly reg. 👍