Fix struct-in-map diffing

Author: Diggsey

Cargo.toml

@@ -1,7 +1,10 @@
 [package]
 name = "serde-diff"
 version = "0.4.1"
-authors = ["Karl Bergström <karl.anton.bergstrom@gmail.com>", "Philip Degarmo <aclysma@gmail.com>"]
+authors = [
+    "Karl Bergström <karl.anton.bergstrom@gmail.com>",
+    "Philip Degarmo <aclysma@gmail.com>",
+]
 readme = "README.md"
 exclude = ["examples/*"]
 license = "Apache-2.0 OR MIT"
@@ -17,10 +20,11 @@ maintenance = { status = "experimental" }
 
 [dependencies]
 serde-diff-derive = { version = "0.4.0", path = "serde-diff-derive" }
-serde =  { version = "1", features = [ "derive" ] }
-serde_derive = { version = "1", features = ["deserialize_in_place"]}
+serde = { version = "1", features = ["derive"] }
+serde_derive = { version = "1", features = ["deserialize_in_place"] }
 
 [dev-dependencies]
 serde_json = "1.0"
 bincode = "1.2"
 rmp-serde = "0.15.0"
+maplit = "1.0.2"

examples/nested_map.rs

@@ -0,0 +1,79 @@
+use maplit::hashmap;
+use serde::{Deserialize, Serialize};
+use serde_diff::{Apply, Diff, SerdeDiff};
+use std::collections::HashMap;
+
+#[derive(SerdeDiff, Serialize, Deserialize, Debug, Default, PartialEq, Clone)]
+struct TestValue {
+    v: String,
+}
+
+#[derive(SerdeDiff, Serialize, Deserialize, Debug, Default, PartialEq, Clone)]
+struct TestStruct {
+    test: bool,
+    map: HashMap<String, HashMap<i32, TestValue>>,
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let mut empty = TestStruct::default();
+    empty.test = true;
+
+    let mut hello_world = TestStruct::default();
+    hello_world.map.insert(
+        "hello".to_string(),
+        hashmap![0 => TestValue { v: "world".to_string()}],
+    );
+
+    let mut hi_world = TestStruct::default();
+    hi_world.map.insert(
+        "hi".to_string(),
+        hashmap![0 => TestValue { v: "world".to_string()}],
+    );
+
+    let mut hi_world_and_planet = TestStruct::default();
+    hi_world_and_planet.map.insert(
+        "hi".to_string(),
+        hashmap![0 => TestValue { v: "world".to_string()}, 1 => TestValue { v: "planet".to_string()}],
+    );
+
+    let mut hi_planet = TestStruct::default();
+    hi_planet.map.insert(
+        "hi".to_string(),
+        hashmap![0 => TestValue { v: "planet".to_string()}],
+    );
+
+    let mut hi_planet_hello_world = TestStruct::default();
+    hi_planet_hello_world.map.insert(
+        "hi".to_string(),
+        hashmap![0 => TestValue { v: "planet".to_string()}],
+    );
+    hi_planet_hello_world.map.insert(
+        "hello".to_string(),
+        hashmap![0 => TestValue { v: "world".to_string()}],
+    );
+
+    let add_hello = serde_json::to_string(&Diff::serializable(&empty, &hello_world))?;
+    let hello_to_hi = serde_json::to_string(&Diff::serializable(&hello_world, &hi_world))?;
+    let add_planet = serde_json::to_string(&Diff::serializable(&hi_world, &hi_world_and_planet))?;
+    let del_world = serde_json::to_string(&Diff::serializable(&hi_world_and_planet, &hi_planet))?;
+    let no_change = serde_json::to_string(&Diff::serializable(&hi_planet, &hi_planet))?;
+    let add_world = serde_json::to_string(&Diff::serializable(&hi_planet, &hi_planet_hello_world))?;
+
+    let mut built = TestStruct::default();
+    for (diff, after) in &[
+        (add_hello, hello_world),
+        (hello_to_hi, hi_world),
+        (add_planet, hi_world_and_planet),
+        (del_world, hi_planet.clone()),
+        (no_change, hi_planet),
+        (add_world, hi_planet_hello_world),
+    ] {
+        println!("{}", diff);
+
+        let mut deserializer = serde_json::Deserializer::from_str(&diff);
+        Apply::apply(&mut deserializer, &mut built)?;
+
+        assert_eq!(after, &built);
+    }
+    Ok(())
+}

src/implementation.rs

@@ -172,6 +172,7 @@ macro_rules! map_serde_diff {
                             if <V as SerdeDiff>::diff(self_value, &mut subctx, other_value)? {
                                 changed = true;
                             }
+                            subctx.pop_path_element()?;
                         },
                         None => {
                             ctx.save_command(&DiffCommandRef::RemoveKey(key), true, true)?;