Fix alias modifier and add serialization tests

src/macros.rs

@@ -21,8 +21,9 @@ macro_rules! message_func {
 macro_rules! message_format {
     [ @st ( $name:ident $field:tt: $type:tt alias = $alias:tt, $($rest:tt)* ) -> ( $($out:tt)* ) ] => {
         message_format![ @st
-            ( $name $field: $type, $($rest)* ) -> (
-                #[serde(rename = $alias)]
+            ( $name $($rest)* ) -> (
+                #[serde(skip_serializing_if = "Option::is_none", rename = $alias)]
+                pub $field: Option<$type>,
                 $($out)*
             )
         ];

src/models/set_activity.rs

@@ -48,3 +48,55 @@ message_format![SetActivitySecrets
     spectate: String,
     game: String alias = "match",
 ];
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json;
+
+    #[test]
+    fn test_set_activity_serialize() {
+        let activity = SetActivity::new()
+            .state("rusting")
+            .instance(true);
+        let json = serde_json::to_string(&activity).unwrap();
+        assert_eq![json, r#"{"instance":true,"state":"rusting"}"#];
+    }
+
+    #[test]
+    fn test_set_activity_timestamps_serialize() {
+        let timestamps = SetActivityTimestamps::new()
+            .start(1000)
+            .end(2000);
+        let json = serde_json::to_string(&timestamps).unwrap();
+        assert_eq![json, r#"{"end":2000,"start":1000}"#];
+    }
+
+    #[test]
+    fn test_set_activity_assets_serialize() {
+        let assets = SetActivityAssets::new()
+            .large_image("ferris")
+            .small_image("rusting");
+        let json = serde_json::to_string(&assets).unwrap();
+        assert_eq![json, r#"{"small_image":"rusting","large_image":"ferris"}"#];
+    }
+
+    #[test]
+    fn test_set_activity_party_serialize() {
+        let party = SetActivityParty::new()
+            .id(1)
+            .size((1, 10));
+        let json = serde_json::to_string(&party).unwrap();
+        assert_eq![json, r#"{"size":[1,10],"id":1}"#];
+    }
+
+    #[test]
+    fn test_set_activity_secrets_serialize() {
+        let secrets = SetActivitySecrets::new()
+            .join("j1")
+            .spectate("s1")
+            .game("g1");
+        let json = serde_json::to_string(&secrets).unwrap();
+        assert_eq![json, r#"{"match":"g1","spectate":"s1","join":"j1"}"#.to_string()];
+    }
+}