Add a failing test for inviting a user with an older gh_id

Assuming gh_id always increases, if we have multiple users with the same
gh_login, the one with the higher id is the most recently valid account
we know about

Author: carols10cents

src/tests/owners.rs

@@ -399,3 +399,25 @@ fn inactive_users_dont_get_invitations() {
     let json = invited_user.list_invitations();
     assert_eq!(json.crate_owner_invitations.len(), 1);
 }
+
+#[test]
+fn highest_gh_id_is_most_recent_account_we_know_of() {
+    let (app, _, owner, owner_token) = TestApp::init().with_token();
+    let owner = owner.as_model();
+
+    // An inactive user with a lower gh_id and an active user with a higher gh_id both exist
+    let invited_gh_login = "user_bar";
+    let krate_name = "newer_user_test";
+
+    // This user will get a lower gh_id, given how crate::new_user works
+    app.db_new_user(invited_gh_login);
+
+    let invited_user = app.db_new_user(invited_gh_login);
+
+    app.db(|conn| { CrateBuilder::new(krate_name, owner.id).expect_build(conn); });
+
+    owner_token.add_user_owner(krate_name, invited_user.as_model());
+
+    let json = invited_user.list_invitations();
+    assert_eq!(json.crate_owner_invitations.len(), 1);
+}