#3654: fix tests

src/__mocks__/holderjs.js

@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2022 PixieBrix, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+export function run(...args) {
+  console.debug("holderjs:run", args);
+}

src/components/documentBuilder/preview/__snapshots__/ElementPreview.test.tsx.snap

@@ -235,6 +235,16 @@ exports[`can preview default header_3 1`] = `
 </DocumentFragment>
 `;
 
+exports[`can preview default image 1`] = `
+<DocumentFragment>
+  <img
+    alt="Placeholder"
+    class=""
+    src="holder.js/50x100"
+  />
+</DocumentFragment>
+`;
+
 exports[`can preview default list 1`] = `
 <DocumentFragment>
   <div