test: add uvl model for mathematically correct expressions

Author: MiriamGaus

tests/parsing/expressions.uvl

@@ -0,0 +1,30 @@
+features
+    A
+        or
+            B {Price 2, Fun 12}
+            C {Price 7, Fun 6}
+constraints
+    B.Fun + C.Fun - B.Price == 16
+    B.Fun + (C.Fun - B.Price) == 16
+    B.Fun + C.Fun * B.Price == 24
+    B.Fun + (C.Fun * B.Price) == 24
+    B.Fun + C.Fun / B.Price == 15
+    B.Fun + (C.Fun / B.Price) == 15
+    B.Fun - C.Fun + B.Price == 8
+    B.Fun - (C.Fun + B.Price) == 4
+    B.Fun - C.Fun * B.Price == 0
+    B.Fun - (C.Fun * B.Price) == 0
+    B.Fun - C.Fun / B.Price == 9
+    B.Fun - (C.Fun / B.Price) == 9
+    B.Fun * C.Fun / B.Price == 36
+    B.Fun * (C.Fun / B.Price) == 36
+    B.Fun * C.Fun - B.Price == 70
+    B.Fun * (C.Fun - B.Price) == 48
+    B.Fun * C.Fun + B.Price == 74
+    B.Fun * (C.Fun + B.Price) == 96
+    B.Fun / C.Fun * B.Price == 4
+    B.Fun / (C.Fun * B.Price) == 1
+    B.Fun / C.Fun + B.Price == 4
+    B.Fun / (C.Fun + B.Price) == 1.5
+    B.Fun / C.Fun - B.Price == 0
+    B.Fun / (C.Fun - B.Price) == 3