feat(extjson): parse legacy {"$date": <ms since epoch>} (#519)

Author: xiangjinwu

src/extjson/models.rs

@@ -256,6 +256,7 @@ pub(crate) struct DateTime {
 pub(crate) enum DateTimeBody {
     Canonical(Int64),
     Relaxed(String),
+    Legacy(i64),
 }
 
 impl DateTimeBody {
@@ -282,6 +283,7 @@ impl DateTime {
                 })?;
                 Ok(datetime)
             }
+            DateTimeBody::Legacy(ms) => Ok(crate::DateTime::from_millis(ms)),
         }
     }
 }

src/tests/serde.rs

@@ -665,6 +665,19 @@ fn test_de_uuid_extjson_string() {
     assert_eq!(actual_uuid_bson, expected_uuid_bson);
 }
 
+#[test]
+fn test_de_date_extjson_number() {
+    let _guard = LOCK.run_concurrently();
+
+    let ext_json_canonical = r#"{ "$date": { "$numberLong": "1136239445000" } }"#;
+    let expected_date_bson: Bson = serde_json::from_str(ext_json_canonical).unwrap();
+
+    let ext_json_legacy_java = r#"{ "$date": 1136239445000 }"#;
+    let actual_date_bson: Bson = serde_json::from_str(ext_json_legacy_java).unwrap();
+
+    assert_eq!(actual_date_bson, expected_date_bson);
+}
+
 #[test]
 fn test_de_oid_string() {
     let _guard = LOCK.run_concurrently();