From dc99ae70b8ddc5b49c9304b834a4a308520ceda6 Mon Sep 17 00:00:00 2001
From: ArsileLuci <42055415+ArsileLuci@users.noreply.github.com>
Date: Fri, 30 Apr 2021 15:13:54 +0300
Subject: [PATCH] Fix fields on interface not being resolved when used with
 fragments (#923, #922)

---
 .../juniper_tests/src/issue_922.rs            | 128 ++++++++++++++++++
 integration_tests/juniper_tests/src/lib.rs    |   2 +
 juniper/CHANGELOG.md                          |   2 +-
 juniper/src/types/async_await.rs              |   5 +-
 juniper/src/types/base.rs                     |   5 +-
 5 files changed, 139 insertions(+), 3 deletions(-)
 create mode 100644 integration_tests/juniper_tests/src/issue_922.rs

diff --git a/integration_tests/juniper_tests/src/issue_922.rs b/integration_tests/juniper_tests/src/issue_922.rs
new file mode 100644
index 00000000..35de87fa
--- /dev/null
+++ b/integration_tests/juniper_tests/src/issue_922.rs
@@ -0,0 +1,128 @@
+use juniper::*;
+
+struct Query;
+
+#[juniper::graphql_object]
+impl Query {
+    fn characters() -> Vec<CharacterValue> {
+        vec![
+            Into::into(Human {
+                id: 0,
+                name: "human-32".to_owned(),
+            }),
+            Into::into(Droid {
+                id: 1,
+                name: "R2-D2".to_owned(),
+            }),
+        ]
+    }
+}
+
+#[juniper::graphql_interface(for = [Human, Droid])]
+trait Character {
+    fn id(&self) -> i32;
+
+    fn name(&self) -> String;
+}
+
+#[derive(juniper::GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+struct Human {
+    pub id: i32,
+    pub name: String,
+}
+
+#[juniper::graphql_interface]
+impl Character for Human {
+    fn id(&self) -> i32 {
+        self.id
+    }
+
+    fn name(&self) -> String {
+        self.name.clone()
+    }
+}
+
+#[derive(juniper::GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+struct Droid {
+    pub id: i32,
+    pub name: String,
+}
+
+#[juniper::graphql_interface]
+impl Character for Droid {
+    fn id(&self) -> i32 {
+        self.id
+    }
+
+    fn name(&self) -> String {
+        self.name.clone()
+    }
+}
+
+type Schema = juniper::RootNode<'static, Query, EmptyMutation<()>, EmptySubscription<()>>;
+
+#[tokio::test]
+async fn test_fragment_on_interface() {
+    let query = r#"
+        query Query {
+            characters {
+                ...CharacterFragment
+            }
+        }
+
+        fragment CharacterFragment on Character {
+            __typename
+            ... on Human {
+                id
+                name
+            }
+            ... on Droid {
+                id
+                name
+            }
+        }
+    "#;
+
+    let (res, errors) = juniper::execute(
+        query,
+        None,
+        &Schema::new(Query, EmptyMutation::new(), EmptySubscription::new()),
+        &Variables::new(),
+        &(),
+    )
+    .await
+    .unwrap();
+
+    assert_eq!(errors.len(), 0);
+    assert_eq!(
+        res,
+        graphql_value!({
+            "characters": [
+                {"__typename": "Human", "id": 0, "name": "human-32"},
+                {"__typename": "Droid", "id": 1, "name": "R2-D2"},
+            ],
+        }),
+    );
+
+    let (res, errors) = juniper::execute_sync(
+        query,
+        None,
+        &Schema::new(Query, EmptyMutation::new(), EmptySubscription::new()),
+        &Variables::new(),
+        &(),
+    )
+    .unwrap();
+
+    assert_eq!(errors.len(), 0);
+    assert_eq!(
+        res,
+        graphql_value!({
+            "characters": [
+                {"__typename": "Human", "id": 0, "name": "human-32"},
+                {"__typename": "Droid", "id": 1, "name": "R2-D2"},
+            ],
+        }),
+    );
+}
diff --git a/integration_tests/juniper_tests/src/lib.rs b/integration_tests/juniper_tests/src/lib.rs
index ce6123d3..a4a9c97f 100644
--- a/integration_tests/juniper_tests/src/lib.rs
+++ b/integration_tests/juniper_tests/src/lib.rs
@@ -21,4 +21,6 @@ mod issue_500;
 #[cfg(test)]
 mod issue_914;
 #[cfg(test)]
+mod issue_922;
+#[cfg(test)]
 mod pre_parse;
diff --git a/juniper/CHANGELOG.md b/juniper/CHANGELOG.md
index 273a0087..f71fce95 100644
--- a/juniper/CHANGELOG.md
+++ b/juniper/CHANGELOG.md
@@ -1,6 +1,6 @@
 # master
 
-- No changes yet
+- Fix fields on interfaces not being resolved when used with fragments ([#923](https://github.com/graphql-rust/juniper/pull/923))
 
 # [[0.15.4] 2021-04-03](https://github.com/graphql-rust/juniper/releases/tag/juniper-0.15.4)
 
diff --git a/juniper/src/types/async_await.rs b/juniper/src/types/async_await.rs
index e1f6e6e1..4fd16aad 100644
--- a/juniper/src/types/async_await.rs
+++ b/juniper/src/types/async_await.rs
@@ -306,7 +306,10 @@ where
                 );
 
                 let concrete_type_name = instance.concrete_type_name(sub_exec.context(), info);
-                if fragment.type_condition.item == concrete_type_name {
+                let type_name = instance.type_name(info);
+                if fragment.type_condition.item == concrete_type_name
+                    || Some(fragment.type_condition.item) == type_name
+                {
                     let sub_result = instance
                         .resolve_into_type_async(
                             info,
diff --git a/juniper/src/types/base.rs b/juniper/src/types/base.rs
index 61d32ca8..014af5de 100644
--- a/juniper/src/types/base.rs
+++ b/juniper/src/types/base.rs
@@ -515,7 +515,10 @@ where
                 );
 
                 let concrete_type_name = instance.concrete_type_name(sub_exec.context(), info);
-                if fragment.type_condition.item == concrete_type_name {
+                let type_name = instance.type_name(info);
+                if fragment.type_condition.item == concrete_type_name
+                    || Some(fragment.type_condition.item) == type_name
+                {
                     let sub_result = instance.resolve_into_type(
                         info,
                         fragment.type_condition.item,