Print tags when printing schemas in the Cedar format (#1304)

Signed-off-by: Shaobo He <shaobohe@amazon.com>

Author: shaobo-he-aws

Cargo.lock

@@ -118,6 +118,10 @@ impl<N: Display> Display for json_schema::EntityType<N> {
             write!(f, " = {ty}")?;
         }
 
+        if let Some(tags) = &self.tags {
+            write!(f, " tags {tags}")?;
+        }
+
         Ok(())
     }
 }
@@ -232,3 +236,27 @@ pub fn json_schema_to_cedar_schema_str<N: Display>(
     }
     Ok(json_schema.to_string())
 }
+
+#[cfg(test)]
+mod tests {
+    use cedar_policy_core::extensions::Extensions;
+
+    use crate::cedar_schema::parser::parse_cedar_schema_fragment;
+
+    #[test]
+    fn rfc_example() {
+        let src = "entity User = {
+            jobLevel: Long,
+          } tags Set<String>;
+          entity Document = {
+            owner: User,
+          } tags Set<String>;";
+        let (cedar_schema, _) =
+            parse_cedar_schema_fragment(src, Extensions::none()).expect("should parse");
+        let printed_cedar_schema = cedar_schema.to_cedarschema().expect("should convert");
+        let (parsed_cedar_schema, _) =
+            parse_cedar_schema_fragment(&printed_cedar_schema, Extensions::none())
+                .expect("should parse");
+        assert_eq!(cedar_schema, parsed_cedar_schema);
+    }
+}

cedar-policy-validator/src/cedar_schema/fmt.rs

@@ -2511,9 +2511,9 @@ mod entity_tags {
     use serde_json::json;
 
     /// This schema taken directly from the RFC 82 text
-    #[test]
-    fn basic() {
-        let json = json!({"": {
+    #[track_caller]
+    fn example_json_schema() -> serde_json::Value {
+        json!({"": {
             "entityTypes": {
                 "User" : {
                     "shape" : {
@@ -2546,7 +2546,20 @@ mod entity_tags {
                 }
             },
             "actions": {}
-        }});
+        }})
+    }
+
+    #[test]
+    fn roundtrip() {
+        let json = example_json_schema();
+        let json_schema = Fragment::from_json_value(json.clone()).expect("should be valid");
+        let serialized_json_schema = serde_json::to_value(json_schema).expect("should be valid");
+        assert_eq!(json, serialized_json_schema);
+    }
+
+    #[test]
+    fn basic() {
+        let json = example_json_schema();
         assert_matches!(Fragment::from_json_value(json), Ok(frag) => {
             let user = frag.0.get(&None).unwrap().entity_types.get(&"User".parse().unwrap()).unwrap();
             assert_matches!(&user.tags, Some(Type::Type(TypeVariant::Set { element })) => {

cedar-policy-validator/src/json_schema.rs

@@ -28,6 +28,7 @@ Cedar Language Version: TBD
 ### Fixed
 
 - Some misleading parser errors for JSON schema with mistakes in nested attribute definitions (#1270, resolving #417)
+- Cedar schema printer now correctly prints entity tags (#1304)
 
 ## [4.2.1] - 2024-10-08
 Cedar Language version: 4.1