Refactor common scripting test code

[philwalk]

This addresses issues described in #12962
It also is relevant to #14073

Refactor test sources:

compiler/test/dotty/tools/scripting/BashScriptsTests.scala
compiler/test/dotty/tools/scripting/ClasspathTests.scala
compiler/test/dotty/tools/scripting/ScriptingTests.scala

Common code is moved to a new file:

compiler/test/dotty/tools/scripting/ScriptTestEnv.scala

So called invalid tests (where permissions fail when running bash command lines) are now treated by default as test failures, although this behavior can be overridden, if needed, by defining PASS_INVALID_TESTS.

[BarkingBad]

Looks good. Sadly, you didn't add [test_non_bootstrapped] and [test_windows_full] in body of your PR to enable these checks.

I think we need to add this trick to CI
types: [ opened, synchronize, reopened, edited ]
from here https://frontside.com/blog/2020-05-26-github-actions-pull_request/#how-do-workflows-trigger-on-pull_request so we could enable the CI without reopening the PR

[philwalk]

add [test_non_bootstrapped] and [test_windows_full] in body of your PR to enable these checks.

So if I add those strings to the PR text, it will enable the addition tests? Ah, I now see the link you provided, I'll read it.

[BarkingBad]

Unfortunately, editing text body now will have no effect, because we don't have edited action listed in the ci.yaml :( We have to open a separate PR with these 2 tags

[michelou]

@philwalk Here are my suggestions :

File scripting/BashScriptsTests.scala

• who does remove the temporary file create on line 21 ?!
  Tip : use annotation org.junit.AfterClass.
• improve comment text on line 59;
  e.g. verify dist/bin/scala with -J setting and Scala script file.
  NB. The same remark applies to the next 3 test functions (-J and -D).
• variable mismatchesin unused on line 98.

File scripting/ScriptTestEnv.scala

• remove 1st (empty) line of file.
• add comment text on line 15; in particular explain the usage of variables TEST_CWD (line 24) and TEST_BASH (line 31).
• add a comment on line 68 to explain the values returned by the bashCommand function !
• add a comment to explain why we may encounter "permission denied" on line 79.
• indent case's in match statement on line 141.

[philwalk]

@michelou - thanks for the feedback, all your suggestions are incorporated in #14113.
We added those and other fixes to a new PR, in order to be able to automatically trigger additional tests:

[test_windows_full]
[test_non_bootstrapped]

[BarkingBad]

No longer valid