Added GUI basic testing implementation

[laim2003]

This PR adds a basic UI test for ide-gui

Implemented changes:

• Added AppBaseTest
• Refactored MainController.java to support Dependency Injection
• Fixed issues with headless testing

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[laim2003]

Seems like the tests fail because a System environment variable is null in the GitHub Actions context, that points to the Project directory (IdeVariables.IDE_ROOT)

Current idea is to refactor MainController to allow Dependency Injection, and then supply the controller with a temporary mock project directory that we create in the test, instead of the directory from the System environment variable.

[laim2003]

Seems like increasing the timeout limits did the trick!

[coveralls]

Pull Request Test Coverage Report for Build 23589507101

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 21 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.2%) to 70.636%

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Files with Coverage Reduction	New Missed Lines	%
com/devonfw/ide/gui/App.java	9	0.0%
com/devonfw/ide/gui/MainController.java	12	66.67%

Totals
Change from base Build 23586480762:	0.2%
Covered Lines:	10827
Relevant Lines:	14711

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💛 - Coveralls

[hohwille]

@laim2003 thanks for your PR and doing the ground-work for automated GUI testing. Great job 👍
BTW: Actually you revealed a bug in the GUI code that if IDE_ROOT is undefined we end up with a NullPointerException. The entire GUI is still in prototype state and needs rework.
But there is already #1295 open with some remaining sub-tasks addressing this.
Therefore, we can easily ignore this here and cleanup later in upcoming PRs.

Ready for merge.

[hohwille]

For the record: The general infrastructure code for GUI tests like the static initializer block need to be moved to an abstract base class for GUI tests since this will not remain to be the only GUI test we ever have in the near future. We then want to reuse instead of doing copy&paste.

[laim2003]

For the record: The general infrastructure code for GUI tests like the static initializer block need to be moved to an abstract base class for GUI tests since this will not remain to be the only GUI test we ever have in the near future. We then want to reuse instead of doing copy&paste.

Good point. I believe opening a seperate Issue would be a bit over the top. Maybe I can push this change today and include it in this PR