fixup pg_test_action_begin

pgrx-examples/decoder/src/lib.rs

@@ -280,11 +280,20 @@ unsafe extern "C" fn pg_decode_shutdown(ctx_ptr: *mut pg_sys::LogicalDecodingCon
 mod tests {
     use pgrx::prelude::*;
 
+    #[pg_test]
+    fn test_action_begin() {
+        use crate::Action;
+
+        let input = Action::begin();
+        let json = serde_json::to_string(&input).expect("Serde Error");
+        assert_eq!(json, "{\"typ\":\"BEGIN\"}");
+    }
+
     #[pg_test]
     #[ignore]
-    fn test_decoder() {
+    fn test_callbacks() {
         //
-        // Not sure how to handle the tests of this extension....
+        // Not sure how to handle the tests of the callbacks....
         // This function is running *inside* a transaction
         // and the WAL decoder will output the changes only when they are
         // committed.