added test

[osman362]

The tree-sitter-modelica was lacking tests to check if each element is shown correctly in the syntax tree. So I added tests for the grammar. For each test I created a small example code and afterwards the syntax tree that should be created based on the grammar. Part of the example code that were used are a direct copy of mtiller/modelica-tree-sitter.

Code copied:

• long_class.txt
• short_class.txt
• Long Class with Decleration
• Long Class with Redecleration
• Simple Equation

Tests for:

• Class (Long , Short , Enumeration, Derivative)
• External function call
• Extend clause
• Component clause
• Redeclaration and Replaceable clause
• Equations (Simple, If, For, While, When and Connect)

[CLAassistant]

All committers have signed the CLA.