From f99cea0c4b2aa18cb5884b7ef6c84d63f67fccad Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C4=93teris=20Pakalns?= <peterispakalns@gmail.com>
Date: Wed, 8 Sep 2021 12:28:33 +0300
Subject: [PATCH] Fix bug in SerdeDerive macro implementation

---
 serde-diff-derive/src/serde_diff/mod.rs |  3 +++
 src/difference.rs                       |  5 +++++
 src/tests.rs                            | 17 +++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/serde-diff-derive/src/serde_diff/mod.rs b/serde-diff-derive/src/serde_diff/mod.rs
index 561ad27..37185bc 100644
--- a/serde-diff-derive/src/serde_diff/mod.rs
+++ b/serde-diff-derive/src/serde_diff/mod.rs
@@ -332,6 +332,9 @@ fn generate(
                 match (self, other) {
                     #(#diff_match_arms)*
                 }
+                if (__changed__) {
+                    ctx.save_exit()?;
+                }
                 Ok(__changed__)
             }
         }
diff --git a/src/difference.rs b/src/difference.rs
index ec80813..ff84c33 100644
--- a/src/difference.rs
+++ b/src/difference.rs
@@ -148,6 +148,11 @@ impl<'a, S: SerializeSeq> DiffContext<'a, S> {
         self.save_command(&DiffCommandRef::Value(value), true, true)
     }
 
+    /// Write exit command
+    pub fn save_exit(&mut self) -> Result<(), S::Error> {
+        self.save_command::<()>(&DiffCommandRef::Exit, true, false)
+    }
+
     /// Stores an arbitrary DiffCommand to be handled by the type.
     /// Any custom sequence of DiffCommands must be followed by Exit.
     pub fn save_command<'b, T: Serialize>(
diff --git a/src/tests.rs b/src/tests.rs
index 082846b..5fccae6 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -1,7 +1,9 @@
 use crate as serde_diff;
 use crate::{Apply, Diff, SerdeDiff};
 use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
 use std::fmt::Debug;
+use std::iter::FromIterator;
 
 #[derive(SerdeDiff, Serialize, Deserialize, PartialEq, Debug, Copy, Clone)]
 struct TestStruct {
@@ -15,6 +17,9 @@ fn roundtrip<T: SerdeDiff + Serialize + for<'a> Deserialize<'a> + PartialEq + De
 ) {
     let diff = Diff::serializable(&old, &new);
     let json_diff = serde_json::to_string(&diff).unwrap();
+
+    println!("{}", json_diff);
+
     let mut deserializer = serde_json::Deserializer::from_str(&json_diff);
     let mut target = old.clone();
     Apply::apply(&mut deserializer, &mut target).unwrap();
@@ -59,6 +64,18 @@ fn test_option() {
         Some(TestStruct { a: 52, b: 32. }),
         Some(TestStruct { a: 42, b: 12. }),
     );
+    roundtrip(
+        HashMap::from_iter([
+            (1, TestStruct { a: 1, b: 1. }),
+            (2, TestStruct { a: 2, b: 2. }),
+            (3, TestStruct { a: 3, b: 3. }),
+        ]),
+        HashMap::from_iter([
+            (1, TestStruct { a: 1, b: 1. }),
+            (3, TestStruct { a: 4, b: 4. }),
+            (4, TestStruct { a: 1, b: 1. }),
+        ]),
+    );
 
     partial(
         Some(TestStruct { a: 5, b: 2. }),