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Tutorial on ModelJUnit for IntelliJ
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In this tutorial, we implemented a model for the `dead code functionality
<https://www.jetbrains.com/help/idea/2017.1/code-inspection.html#d872021e416>`_, according to the below image:

.. image:: deadcode.png

We looked at how to start out with the sample code for lab 3 to implement both
the adapter and the model in ModelJUnit_. You can find the solution on `GitHub <https://github.com/zut/intellij-community/commit/f7504be4cc2e6722bb8c0f046cff700f701d0a41>`_. We had a look at how to find the code
that corresponds to some functionality in the IDE, in roughly the following steps:

- First a text-search in the entire IDE, to find where the text that is on the button we click is located. In our case we found that the text ``"Remove 'if' statement"`` was found in the ``SimplifyBooleanExpressionFix`` classe)
- The text on a button will be connected to the action somehow, using ''Find Usages'' on the ``getText()`` method, we found the method ``DataFlowInspectionBase::createSimplifyBooleanExpressionFix``
- This method returns a ``LocalQuickFix`` object, which contains a label and a callback -- this pattern is common when programmatically generating clickable UI elements
- By starting IntelliJ in debug mode (from inside IntelliJ), we were able to verify when the respective parts of the code is run by placing breakpoints in the callback method.
- Now, we went rouge and stole the code from ``DataFlowInspectionBase`` and placed it in the `adapter <https://github.com/zut/intellij-community/commit/f7504be4cc2e6722bb8c0f046cff700f701d0a41#diff-8c89001ea96713a189da3ef914c066fb>`_, through ordinary copy-paste.
- This gave some compilation issues which had to be worked out. We also had to steal the ``createIntention()`` method, and we had to figure out how to get a ``PsiElement`` from the ``Editor`` object available in the adapter.
- Now we just have to move the carret around to select the correct ``PsiElement`` (needed to call `.getParent()` twice to not only select the `a` variable, but the entire expression).
- Finally, we've assempled ``SimplifyBooleanExpressionFix fix = createIntention(psiElement);``, and are eager to try out ``fix.applyFix()``. But alas! This doesnt work, as we need to be in a "transaction" so that our actions can be undone (rather than undoing one character a time, the whole action can be undone).
- This is solved by running the commands in a ``CommandProcessor``, in which we call ``PsiDocumentManager.getInstance(getProject()).commitAllDocuments()`` and also wrap ``fix.applyFix`` as ``WriteAction.run(fix::applyFix)``


.. _ModelJUnit: http://www.cs.waikato.ac.nz/~marku/mbt/modeljunit/