Add a unit test to ensure extensions are loaded on shareBlocksToTarget

test/unit/virtual-machine.js

@@ -910,6 +910,35 @@ test('shareBlocksToTarget chooses a fresh name for a new global variable checkin
     });
 });
 
+test('shareBlocksToTarget loads extensions that have not yet been loaded', t => {
+    const vm = new VirtualMachine();
+    const runtime = vm.runtime;
+    const spr1 = new Sprite(null, runtime);
+    const stage = spr1.createClone();
+    runtime.targets = [stage];
+
+    const fakeBlocks = [
+        {opcode: 'loaded_fakeblock'},
+        {opcode: 'notloaded_fakeblock'}
+    ];
+
+    // Stub the extension manager
+    const loadedIds = [];
+    vm.extensionManager = {
+        isExtensionLoaded: id => id === 'loaded',
+        loadExtensionURL: id => new Promise(resolve => {
+            loadedIds.push(id);
+            resolve();
+        })
+    };
+
+    vm.shareBlocksToTarget(fakeBlocks, stage.id).then(() => {
+        // Verify that only the not-loaded extension gets loaded
+        t.deepEqual(loadedIds, ['notloaded']);
+        t.end();
+    });
+});
+
 test('Setting turbo mode emits events', t => {
     let turboMode = null;