add test showing value types rules are broken

src/type_system/tests.rs

@@ -13,7 +13,8 @@ mod new_with_self_references;
 mod permission_check;
 mod subtyping;
 mod type_check;
-mod value_types;
+mod value_type_permissions;
+mod value_type_subtyping;
 mod variance_subtyping;
 
 /// Check what happens when we encounter a bad class name in a function parameter.

src/type_system/tests/value_type_permissions.rs

@@ -0,0 +1,25 @@
+use formality_core::test;
+use formality_core::test_util::ResultTestExt;
+
+use crate::{dada_lang::term, type_system::check_program};
+
+#[test]
+#[ignore = "FIXME, broken"]
+fn give_int_value_twice() {
+    check_program(&term(
+        "
+                class Foo {
+                    i: Int;
+                }
+
+                class Main {
+                    fn main(my self, foo: my Foo) {
+                        foo.i.give;
+                        foo.i.give;
+                        ();
+                    }
+                }
+            ",
+    ))
+    .assert_ok(expect_test::expect![["()"]])
+}