tests: workaround perfectscroll importing issue in jest

src/common-elements/perfect-scrollbar.tsx

@@ -1,22 +1,30 @@
 import * as React from 'react';
 
-import { default as PerfectScrollbarConstructor } from 'perfect-scrollbar';
+import PerfectScrollbarType, * as PerfectScrollbarNamespace from 'perfect-scrollbar';
 import psStyles from 'perfect-scrollbar/css/perfect-scrollbar.css';
 import styled, { injectGlobal } from '../styled-components';
 
+/*
+ * perfect scrollbar umd bundle uses exports assignment while module uses default export
+ * so when bundled with webpack default export works but with jest it crashes
+ * That's why the following ugly fix is required
+ */
+const PerfectScrollbarConstructor =
+ PerfectScrollbarNamespace.default || ((PerfectScrollbarNamespace as any) as PerfectScrollbarType);
+
 injectGlobal`${psStyles && psStyles.toString()}`;
 
 const StyledScrollWrapper = styled.div`
  position: relative;
 `;
 
 export class PerfectScrollbar extends React.Component<{
- options?: PerfectScrollbarConstructor.Options;
+ options?: PerfectScrollbarType.Options;
  className?: string;
  updateFn: (fn) => void;
 }> {
  private _container: HTMLElement;
- private inst: PerfectScrollbarConstructor;
+ private inst: PerfectScrollbarType;
 
  componentDidMount() {
  this.inst = new PerfectScrollbarConstructor(this._container, this.props.options || {});