Mutation type is not available in OperationVisitor

Author: kamilkisiela

src/validation/rules/fields_on_correct_type.rs

@@ -112,6 +112,9 @@ pub static FIELDS_ON_CORRECT_TYPE_TEST_SCHEMA: &str = "
   type Query {
     human: Human
   }
+  type Mutation {
+    deletePetByName(name: String): Pet
+  }
 ";
 
 #[test]
@@ -213,6 +216,48 @@ fn ignores_fields_on_unknown_type() {
     assert_eq!(get_messages(&errors).len(), 0);
 }
 
+#[test]
+fn unknown_query_field() {
+    use crate::validation::test_utils::*;
+
+    let mut plan = create_plan_from_rule(Box::new(FieldsOnCorrectType {}));
+    let errors = test_operation_with_schema(
+        "query test {
+          unknownField
+        }",
+        &FIELDS_ON_CORRECT_TYPE_TEST_SCHEMA,
+        &mut plan,
+    );
+
+    let messages = get_messages(&errors);
+    assert_eq!(messages.len(), 1);
+    assert_eq!(
+        messages,
+        vec!["Cannot query field \"unknownField\" on type \"Query\"."]
+    );
+}
+
+#[test]
+fn unknown_mutation_field() {
+    use crate::validation::test_utils::*;
+
+    let mut plan = create_plan_from_rule(Box::new(FieldsOnCorrectType {}));
+    let errors = test_operation_with_schema(
+        "mutation test {
+          unknownField
+        }",
+        &FIELDS_ON_CORRECT_TYPE_TEST_SCHEMA,
+        &mut plan,
+    );
+
+    let messages = get_messages(&errors);
+    assert_eq!(messages.len(), 1);
+    assert_eq!(
+        messages,
+        vec!["Cannot query field \"unknownField\" on type \"Mutation\"."]
+    );
+}
+
 #[test]
 fn reports_errors_when_type_is_known_again() {
     use crate::validation::test_utils::*;