From 9e0549ba8b8e55b619ee87dc5fa71caee4a65cd4 Mon Sep 17 00:00:00 2001
From: Muffin <muffin@mailbox.org>
Date: Tue, 25 Jul 2023 23:26:00 -0500
Subject: [PATCH] Fix regression where extensions used by monitors were not
 saved

Caught by test
---
 src/serialization/sb3.js | 87 +++++++++++++++++++---------------------
 1 file changed, 42 insertions(+), 45 deletions(-)

diff --git a/src/serialization/sb3.js b/src/serialization/sb3.js
index 444b15bf667..cfd568bb1ec 100644
--- a/src/serialization/sb3.js
+++ b/src/serialization/sb3.js
@@ -580,6 +580,45 @@ const serializeMonitors = function (monitors, runtime, extensions) {
         .toArray();
 };
 
+/**
+ * @param {any} obj Project or target JSON. Modified in place.
+ * @param {Set<string>} extensionIds
+ * @param {Runtime} runtime
+ * @param {boolean} isSprite
+ * @returns {void} nothing, operates in-place
+ */
+const serializeExtensionMetadata = (obj, extensionIds, runtime, isSprite) => {
+    const serializedExtensions = Array.from(extensionIds);
+    if (serializedExtensions.length || !isSprite) {
+        obj.extensions = serializedExtensions;
+    }
+
+    // Save list of URLs to load the current extensions
+    // Extension manager only exists when runtime is wrapped by VirtualMachine
+    if (runtime.extensionManager) {
+        // We'll save the extensions in the format:
+        // {
+        //   "extensionid": "https://...",
+        //   "otherid": "https://..."
+        // }
+        // Which lets the VM know which URLs correspond to which IDs, which is useful when the project
+        // is being loaded. For example, if the extension is eventually converted to a builtin extension
+        // or if it is already loaded, then it doesn't need to fetch the script again.
+        const extensionURLs = runtime.extensionManager.getExtensionURLs();
+        const urlsToSave = {};
+        for (const extension of extensionIds) {
+            const url = extensionURLs[extension];
+            if (typeof url === 'string') {
+                urlsToSave[extension] = url;
+            }
+        }
+        // Only save this object if any URLs would actually be saved.
+        if (Object.keys(urlsToSave).length !== 0) {
+            obj.extensionURLs = urlsToSave;
+        }
+    }
+};
+
 /**
  * Serializes the specified VM runtime.
  * @param {!Runtime} runtime VM runtime instance to be serialized.
@@ -610,60 +649,18 @@ const serialize = function (runtime, targetId, {allowOptimization = true} = {})
 
     const serializedTargets = flattenedOriginalTargets.map(t => serializeTarget(t, extensions));
 
-    const serialiedExtensionList = Array.from(extensions);
-
-    // Save list of URLs to load the current extensions
-    // Extension manager only exists when runtime is wrapped by VirtualMachine
-    let serializedExtensionURLs = null;
-    if (runtime.extensionManager) {
-        // We'll save the extensions in the format:
-        // {
-        //   "extensionid": "https://...",
-        //   "otherid": "https://..."
-        // }
-        // Which lets the VM know which URLs correspond to which IDs, which is useful when the project
-        // is being loaded. For example, if the extension is eventually converted to a builtin extension
-        // or if it is already loaded, then it doesn't need to fetch the script again.
-        const extensionURLs = runtime.extensionManager.getExtensionURLs();
-        const urlsToSave = {};
-        for (const extension of extensions) {
-            const url = extensionURLs[extension];
-            if (typeof url === 'string') {
-                urlsToSave[extension] = url;
-            }
-        }
-        // Only save this object if any URLs would actually be saved.
-        if (Object.keys(urlsToSave).length !== 0) {
-            serializedExtensionURLs = urlsToSave;
-        }
-    }
-
     if (targetId) {
         const target = serializedTargets[0];
-
-        // Scratch doesn't save extensions for sprites, so don't add if not needed.
-        if (serialiedExtensionList.length) {
-            target.extensions = serialiedExtensionList;
-        }
-        if (serializedExtensionURLs) {
-            target.extensionURLs = serializedExtensionURLs;
-        }
-
+        serializeExtensionMetadata(target, extensions, runtime, true);
         return serializedTargets[0];
     }
 
-    // This is part of Scratch
-    obj.extensions = serialiedExtensionList;
-
-    // This is not part of Scratch, so don't add if not needed.
-    if (serializedExtensionURLs) {
-        obj.extensionURLs = serializedExtensionURLs;
-    }
-
     obj.targets = serializedTargets;
 
     obj.monitors = serializeMonitors(runtime.getMonitorState(), runtime, extensions);
 
+    serializeExtensionMetadata(obj, extensions, runtime, false);
+
     // Assemble metadata
     const meta = Object.create(null);
     meta.semver = '3.0.0';