diff --git a/types/doubleclick-gpt/doubleclick-gpt-tests.ts b/types/doubleclick-gpt/doubleclick-gpt-tests.ts
index 7b83ec7679..d5991e0271 100644
--- a/types/doubleclick-gpt/doubleclick-gpt-tests.ts
+++ b/types/doubleclick-gpt/doubleclick-gpt-tests.ts
@@ -291,6 +291,12 @@ googletag.pubads().addEventListener("impressionViewable", (event) => {
     }
 });
 
+googletag.pubads().addEventListener("slotVisibilityChanged", (event) => {
+    if (event.slot === targetSlot) {
+        console.log(event.inViewPercentage)
+    }
+});
+
 let mapping1 = googletag.sizeMapping().
         addSize([1024, 768], [970, 250]).
         addSize([980, 690], [728, 90]).