From 8bb8705dbeb8a82c17e47ca17bd9d3febdc72dc5 Mon Sep 17 00:00:00 2001
From: Kevin Reid <kpreid@switchb.org>
Date: Wed, 19 Jun 2024 10:59:42 -0700
Subject: [PATCH] Add tests for `HandleError`s from transactions.

---
 all-is-cubes/src/transaction.rs           | 18 ++++++++++++++++++
 all-is-cubes/src/universe/universe_txn.rs | 22 +++++++++++++++++++++-
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/all-is-cubes/src/transaction.rs b/all-is-cubes/src/transaction.rs
index a0cb005f1..a80f39fb7 100644
--- a/all-is-cubes/src/transaction.rs
+++ b/all-is-cubes/src/transaction.rs
@@ -292,6 +292,24 @@ where
     }
 }
 
+/// Note: [`ExecuteError::Commit`] never compares equal, because it contains
+/// arbitrary errors which may not implement [`PartialEq`].
+/// TODO: push this down to `impl PartialEq for CommitError` for more precision.
+impl<Txn> PartialEq for ExecuteError<Txn>
+where
+    Txn: Transaction<Mismatch: PartialEq> + Merge<Conflict: PartialEq>,
+{
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Self::Merge(a), Self::Merge(b)) => a == b,
+            (Self::Check(a), Self::Check(b)) => a == b,
+            (Self::Commit(_), Self::Commit(_)) => false,
+            (Self::Handle(a), Self::Handle(b)) => a == b,
+            _ => false,
+        }
+    }
+}
+
 /// Error type returned by [`Transaction::check`].
 ///
 /// Note: This type is designed to be cheap to construct, as it is expected that game
diff --git a/all-is-cubes/src/universe/universe_txn.rs b/all-is-cubes/src/universe/universe_txn.rs
index edd625eeb..8694c2cc2 100644
--- a/all-is-cubes/src/universe/universe_txn.rs
+++ b/all-is-cubes/src/universe/universe_txn.rs
@@ -222,7 +222,7 @@ pub struct UniverseCommitCheck {
 }
 
 /// Transaction conflict error type for [`UniverseTransaction`].
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 #[non_exhaustive]
 pub enum UniverseConflict {
     /// The two transactions modify members of different [`Universe`]s.
@@ -843,6 +843,7 @@ mod tests {
     use crate::space::SpaceTransaction;
     use crate::space::SpaceTransactionConflict;
     use crate::transaction::{ExecuteError, MapConflict, TransactionTester};
+    use crate::universe::HandleError;
     use alloc::sync::Arc;
     use indoc::indoc;
 
@@ -1136,4 +1137,23 @@ mod tests {
             })
         ));
     }
+
+    #[test]
+    fn handle_error_from_handle_execute() {
+        let e = Handle::<Space>::new_gone("foo".into())
+            .execute(&SpaceTransaction::default())
+            .unwrap_err();
+
+        assert_eq!(e, ExecuteError::Handle(HandleError::Gone("foo".into())));
+    }
+
+    // This is not specifically desirable, but more work will be needed to avoid it
+    #[test]
+    #[should_panic = "Attempted to execute transaction with target already borrowed: Gone(Specific(\"foo\"))"]
+    fn handle_error_from_universe_txn() {
+        let mut u = Universe::new();
+        let txn = SpaceTransaction::default().bind(Handle::<Space>::new_gone("foo".into()));
+
+        _ = txn.execute(&mut u, &mut transaction::no_outputs);
+    }
 }