prefix expressions

vm/vm_test.go

@@ -119,6 +119,10 @@ func TestIntegerArithmetic(t *testing.T) {
 		{"(1 < 2) == false", false},
 		{"(1 > 2) == true", false},
 		{"(1 > 2) == false", true},
+		{"-5", -5},
+		{"-10", -10},
+		{"-50 + 100 + -50", 0},
+		{"(5 + 10 * 2 + 15 / 3) * 2 + -10", 50},
 	}
 
 	runVmTests(t, tests)
@@ -128,6 +132,12 @@ func TestBooleanExpressions(t *testing.T) {
 	tests := []vmTestCase{
 		{"true", true},
 		{"false", false},
+		{"!true", false},
+		{"!false", true},
+		{"!5", false},
+		{"!!true", true},
+		{"!!false", false},
+		{"!!5", true},
 	}
 
 	runVmTests(t, tests)