read global package.mask

tests/profile/read_mock_profile.rs

@@ -8,6 +8,16 @@ fn main() {
         .nth(1)
         .expect("expected path to mockrepo as first argument");
     let repo = Repo::new(&repo_path).expect("failed to read repo");
+
+    let global_package_mask = repo
+        .package_mask()
+        .iter()
+        .map(Atom::to_string)
+        .sorted()
+        .collect::<Vec<_>>();
+
+    assert_eq!(global_package_mask, vec!["app-editors/vim"]);
+
     let profile = repo
         .evaluate_profile("gentoo-desktop")
         .expect("failed to evaluate profile");