Make TUI refuse to show non-installed workflows

[wxtim]

These changes close #4715

Summary

When Cylc TUI is started it should check whether the workflow has actually been installed before doing anything to display it.

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).
• Applied any dependency changes to both setup.cfg and conda-environment.yml.
• Appropriate tests are included (unit and/or functional).
• Appropriate change log entry included.
• Change log rebased after 8.0rc2 release.
• No documentation update required.

[MetRonnie]

My observations from testing out:

• If a workflow dir does not exist, TUI refuses to load and instead you get a message

  UserInputError: Path does not exist: ~/cylc-run/dir
  

• If the dir does exist in ~/cylc-run, but does not contain a flow.cylc or suite.rc, you get the "workflow not found" message inside TUI as expected
• However, you still have the option to play it in the menu when you press Enter, only for it come up with an error

  WorkflowFilesError: No flow.cylc or suite.rc in ~/cylc-run/dir
  

• Also, if the dir is a parent of a run dir, it says "workflow not found" inside TUI, which is perhaps misleading

[wxtim]

@MetRonnie - Can you clarify exactly what you mean in #4715 by cylc tui non-exist? Is non-exist a non-existant workflow folder? Or a real folder without a clearly identified workflow within it?

[MetRonnie]

I can't remember. Either it was a non-existent folder, which means the UserInputError is new since then, or it was an empty folder or something like that

[wxtim]

Also, if the dir is a parent of a run dir, it says "workflow not found" inside TUI, which is perhaps misleading

Can it be the parent of a run-dir?

[MetRonnie]

Also, if the dir is a parent of a run dir, it says "workflow not found" inside TUI, which is perhaps misleading

Can it be the parent of a run-dir?

Not sure what you mean. Here is an example of what I was talking about:

$ tree -L 1 ~/cylc-run/blah
~/cylc-run/blah
|-- _cylc-install
|-- run1
`-- runN -> run1

$ cylc tui blah

[wxtim]

@MetRonnie - using the equivalent of your example I get Cylc TUI saying

temp1/run1 - workflow not found

By the point that the logic I've inserted takes place any input has been expanded to a full workflow name. Isn't this the same expansion behaviour as the rest of the CLI?

[MetRonnie]

Ah, I oversimplified my example. Try this instead (another level in the directory structure):

$ cd ~/cylc-run
$ tree -L 2 foo
foo
`-- bar
    |-- _cylc-install
    |-- run1
    `-- runN -> run1

$ cylc tui foo

[oliver-sanders]

My observations from testing out:

If a workflow dir does not exist, TUI refuses to load and instead you get a message
UserInputError: Path does not exist: ~/cylc-run/dir

Good

If the dir does exist in ~/cylc-run, but does not contain a flow.cylc or suite.rc, you get the "workflow not > found" message inside TUI as expected

Good

However, you still have the option to play it in the menu when you press Enter, only for it come up with an error
WorkflowFilesError: No flow.cylc or suite.rc in ~/cylc-run/dir

Fine IMO. I don't think we need to obsess about these niche cases.

Also, if the dir is a parent of a run dir, it says "workflow not found" inside TUI, which is perhaps misleading

Fine IMO, same result as you would get with any other Cylc command.

[MetRonnie]

Perhaps "No flow.cylc or suite.rc in ~/cylc-run/dir" would be better than "Workflow not found"?

Can just use cylc.flow.workflow_files.check_flow_file() and use the string representation of the WorkflowFilesError that gets raised for no flow file

[datamel]

I have manually tested this, working well for me.