[vala/0.40] tests: Extend "GenericAccessors" test to increase coverage

[Rico Tzschichholz <ricotz src gnome org>]

commit ae6c3d9d2a6303cf81d7a136e4e9ec41115ca6fd
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sat Mar 7 10:50:21 2020 +0100

    tests: Extend "GenericAccessors" test to increase coverage

 tests/generics/bug640330.vala | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/tests/generics/bug640330.vala b/tests/generics/bug640330.vala
index 44c5cd9a5..e57ccb074 100644
--- a/tests/generics/bug640330.vala
+++ b/tests/generics/bug640330.vala
@@ -1,6 +1,10 @@
 [GenericAccessors]
 interface Foo<G> : Object {
        public virtual G get_foo (G g) {
+               assert (typeof (G) == typeof (string));
+               G g_copy = g;
+               assert (GLib.strcmp ((string) g_copy, "foo") == 0);
+               assert (g_copy != g);
                return g;
        }
 }