Snapshot test recharts plots

[chaoran-chen]

Our widget snapshot tests are not covering the plots generated by recharts, the container divs are simply empty:

cov-spectrum-website/src/widgets/__tests__/__snapshots__/VariantTimeDistributionLineChart.test.tsx.snap

Lines 127 to 139 in 6b7ad13

	<div
	className="recharts-responsive-container"
	style={
	Object {
	"height": "100%",
	"maxHeight": undefined,
	"minHeight": undefined,
	"minWidth": undefined,
	"width": "100%",
	}
	}
	/>
	</div>

We should consider testing them. It might, however, not be very easy: when I tried in #1112, I encountered the issue that the tests generated different snapshots on my devince than in the CI.

We should update to recharts v3 (#1111) first.

The following mock snippet might be useful – to be placed under src/__mocks__/recharts:

import React from 'react';

module.exports = {
  ...jest.requireActual('recharts'),
  ResponsiveContainer: ({ children }: { children: any }) =>
    React.cloneElement(React.Children.only(children), { width: 800, height: 400 }),
};