add diagram renderer mocks

__mocks__/sequenceRenderer.js

@@ -0,0 +1,23 @@
+/**
+ * Mocked sequence diagram renderer
+ */
+
+import { vi } from 'vitest';
+
+export const bounds = vi.fn();
+export const drawActors = vi.fn();
+export const drawActorsPopup = vi.fn();
+
+export const setConf = vi.fn();
+
+export const draw = vi.fn().mockImplementation(() => {
+  return '';
+});
+
+export default {
+  bounds,
+  drawActors,
+  drawActorsPopup,
+  setConf,
+  draw,
+};