From 420d8146b69189450ae60196817bc9dded9dba92 Mon Sep 17 00:00:00 2001
From: Enrique Ortiz <hi@enriqueortiz.dev>
Date: Thu, 11 May 2023 18:20:11 -0400
Subject: [PATCH] chore: be able to match in between events rather than
 strictly full-sequences

---
 .../executor/inspector/cheatcodes/expect.rs   | 12 +++++-
 testdata/cheats/ExpectEmit.t.sol              | 42 +++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/evm/src/executor/inspector/cheatcodes/expect.rs b/evm/src/executor/inspector/cheatcodes/expect.rs
index e8cf12c46cd7..d97d44c1ee65 100644
--- a/evm/src/executor/inspector/cheatcodes/expect.rs
+++ b/evm/src/executor/inspector/cheatcodes/expect.rs
@@ -180,13 +180,23 @@ pub fn handle_expect_emit(state: &mut Cheatcodes, log: RawLog, address: &Address
                     event_to_fill_or_check.found &= expected.data == log.data;
                 }
             }
+
+            // If we found the event, we can push it to the back of the queue
+            // and begin expecting the next event.
+            if event_to_fill_or_check.found {
+                state.expected_emits.push_back(event_to_fill_or_check);
+            } else {
+                // We did not match this event, so we need to keep waiting for the right one to appear.
+                state.expected_emits.push_front(event_to_fill_or_check);
+            }
+
         }
         // Fill the event.
         None => {
             event_to_fill_or_check.log = Some(log);
+            state.expected_emits.push_back(event_to_fill_or_check);
         }
     }
-    state.expected_emits.push_back(event_to_fill_or_check);
 }
 
 #[derive(Clone, Debug, Default)]
diff --git a/testdata/cheats/ExpectEmit.t.sol b/testdata/cheats/ExpectEmit.t.sol
index b801c6fa2dfa..be3c58254b21 100644
--- a/testdata/cheats/ExpectEmit.t.sol
+++ b/testdata/cheats/ExpectEmit.t.sol
@@ -17,6 +17,8 @@ contract Emitter {
     /// Ref: issue #760
     event SomethingElse(uint256 data);
 
+    event SomethingNonIndexed(uint256 data);
+
     function emitEvent(uint256 topic1, uint256 topic2, uint256 topic3, uint256 data) public {
         emit Something(topic1, topic2, topic3, data);
     }
@@ -36,6 +38,13 @@ contract Emitter {
         emitNested(Emitter(address(this)), 1, 2, 3, 4);
     }
 
+    function emitOutOfExactOrder() public {
+        emit SomethingNonIndexed(1);
+        emit Something(1, 2, 3, 4);
+        emit Something(1, 2, 3, 4);
+        emit Something(1, 2, 3, 4);
+    }
+
     function emitNested(Emitter inner, uint256 topic1, uint256 topic2, uint256 topic3, uint256 data) public {
         inner.emitEvent(topic1, topic2, topic3, data);
     }
@@ -74,6 +83,8 @@ contract ExpectEmitTest is DSTest {
 
     event SomethingElse(uint256 indexed topic1);
 
+    event SomethingNonIndexed(uint256 data);
+
     function setUp() public {
         emitter = new Emitter();
     }
@@ -217,6 +228,37 @@ contract ExpectEmitTest is DSTest {
         );
     }
 
+    function testExpectEmitCanMatchWithoutExactOrder() public {
+        cheats.expectEmit(true, true, true, true);
+        emit Something(1, 2, 3, 4);
+        cheats.expectEmit(true, true, true, true);
+        emit Something(1, 2, 3, 4);
+
+        emitter.emitOutOfExactOrder();
+    }
+
+    function testFailExpectEmitCanMatchWithoutExactOrder() public {
+        cheats.expectEmit(true, true, true, true);
+        emit Something(1, 2, 3, 4);
+        // This should fail, as this event is never emitted 
+        // in between the other two Something events.
+        cheats.expectEmit(true, true, true, true);
+        emit SomethingElse(1);
+        cheats.expectEmit(true, true, true, true);
+        emit Something(1, 2, 3, 4);
+
+        emitter.emitOutOfExactOrder();
+    }
+
+    function testExpectEmitCanMatchWithoutExactOrder2() public {
+        cheats.expectEmit(true, true, true, true);
+        emit SomethingNonIndexed(1);
+        cheats.expectEmit(true, true, true, true);
+        emit Something(1, 2, 3, 4);
+
+        emitter.emitOutOfExactOrder();
+    }
+
     function testExpectEmitAddress() public {
         cheats.expectEmit(address(emitter));
         emit Something(1, 2, 3, 4);