Allow using tasks in `preconditions` (possibly `status`)

[DerpgonCz]

Using task: ... in preconditions

This feature requests aims to allow using task: ... property in preconditions array of a task.

Currently, preconditions is an array of either string (interpreted as shell commands) or an array of objects with sh (also interpreted as a shell command) and msg (interpreted as a string) being printed when given shell command exits with a return code != 0.

Example:

version: '3'

tasks:
  positive:
    cmd: exit 0

  negative:
    cmd: exit 2

  test-positive:
    preconditions:
      - task: positive
    cmd: echo "I am OK"

  test-negative:
    preconditions:
      - task: negative
        msg: Precondition negative failed
    cmd: echo "I am not ok"

  test-invalid:
    preconditions:
      - task: positive
        sh: exit 1

Acceptance criteria: (check indicates whether current behavior fulfills the criteria)

• ✅ Running task positive should not do anything
• ✅ Running task negative should fail with exit code 2
• ❌ Running task test-positive should check the precondition
• ✅ Running task test-positive should print I am OK
• ❌ Running task test-negative should check the precondition
• ❌ Running task test-negative should print Precondition negative failed exit with an error code 1
  • not sure if it should inherit the error code or not
• ❌ Running task test-negative should not print I am not OK
• ❌ Running task test-invalid should not be valid
  • or throw a validation error on running any task, as the file is technically not valid

Backwards compatibility is assured, as this is just an expansion to the existing object used as an array item in preconditions. Using both sh and task should not be valid declaration of a precondition.

Using task: ... in status

Similiar as above, however it is an expansion to allowed structure for status, as it currently does not allow objects, but only strings. It is possible to create a new feature request if these two features in one request are a different scope, but I did not want to create a new issue for it and would rather see if the above passes before creating it.

Afterword

I am aware that deps are already usable, however it is not possible to use --force to skip them.