implement junit tests

src/test/java/Helper.java

@@ -0,0 +1,36 @@
+import java.util.*;
+
+import org.antlr.v4.runtime.*;
+import org.antlr.v4.runtime.tree.*;
+
+import de.hsrm.compiler.Klang.*;
+import de.hsrm.compiler.Klang.helper.*;
+import de.hsrm.compiler.Klang.nodes.*;
+
+public class Helper {
+    public static ParseTree prepareParser(String input) {
+        CharStream inStream = CharStreams.fromString(input);
+        KlangLexer lexer = new KlangLexer(inStream);
+        CommonTokenStream tokens = new CommonTokenStream(lexer);
+        KlangParser parser = new KlangParser(tokens);
+        return parser.parse();
+    }
+
+    public static Map<String, FunctionInformation> getFuncs(ParseTree tree) {
+        var functionDefinitions = new HashMap<String, FunctionInformation>();
+        new GetFunctions(functionDefinitions).visit(tree);
+        return functionDefinitions;
+    }
+
+    public static Set<String> getStructNames(ParseTree tree) {
+        var structNames = new HashSet<String>();
+        new GetStructNames(structNames).visit(tree);
+        return structNames;
+    }
+
+    public static Map<String, StructDefinition> getStructs(ParseTree tree) {
+        var structs = new HashMap<String, StructDefinition>();
+        new GetStructs(getStructNames(tree), structs).visit(tree);
+        return structs;
+    }
+}