Fix file input in tests

test/helper/page-util.js

@@ -0,0 +1,53 @@
+/* global window, VirtualMachine, ScratchStorage, ScratchSVGRenderer */
+/* eslint-env browser */
+
+// Wait for all SVG skins to be loaded.
+// TODO: this is extremely janky and should be removed once vm.loadProject waits for SVG skins to load
+window.waitForSVGSkinLoad = renderer => new Promise(resolve => {
+    // eslint-disable-next-line prefer-const
+    let interval;
+
+    const waitInner = () => {
+        let numSVGSkins = 0;
+        let numLoadedSVGSkins = 0;
+        for (const skin of renderer._allSkins) {
+            if (skin.constructor.name !== 'SVGSkin') continue;
+            numSVGSkins++;
+            if (skin._svgRenderer.loaded) numLoadedSVGSkins++;
+        }
+
+        if (numSVGSkins === numLoadedSVGSkins) {
+            clearInterval(interval);
+            resolve();
+        }
+    };
+
+    interval = setInterval(waitInner, 1);
+});
+
+window.loadFileInputIntoVM = (fileInput, vm, render) => {
+    const reader = new FileReader();
+    return new Promise(resolve => {
+        reader.onload = () => {
+            vm.start();
+            vm.loadProject(reader.result)
+                .then(() => window.waitForSVGSkinLoad(render))
+                .then(() => {
+                    resolve();
+                });
+        };
+        reader.readAsArrayBuffer(fileInput.files[0]);
+    });
+};
+
+window.initVM = render => {
+    const vm = new VirtualMachine();
+    const storage = new ScratchStorage();
+
+    vm.attachStorage(storage);
+    vm.attachRenderer(render);
+    vm.attachV2SVGAdapter(new ScratchSVGRenderer.SVGRenderer());
+    vm.attachV2BitmapAdapter(new ScratchSVGRenderer.BitmapAdapter());
+
+    return vm;
+};