Add test code

test/arith.w12

@@ -0,0 +1,43 @@
+fn factorial(n: int) -> int {
+	var result: int;
+
+	if n == 0 {
+		result = 1;
+	} else {
+		result = n * factorial(n - 1);
+	}
+
+	return result;
+}
+
+fn is_positive(n: int) -> bool {
+	return n > 0;
+}
+
+fn main() -> int {
+	var a: int = 5;
+	printf("a = %d\n", a);
+
+	var b: int = 3;
+	printf("b = %d\n", b);
+
+	var c: int = (a + b) * 2 - 1;
+	c += factorial(5);
+
+	printf("c = %d\n", c);
+
+	while c > 0 {
+		printf("c = %d\n", c);
+
+		if c > 50 {
+			printf("c is greater than 50\n");
+		} else {
+			printf("c is less than or equal to 50\n");
+		}
+
+		c -= 16;
+	}
+
+	printf("End result: %d\n", c);
+	return 0;
+}