Swap over to Jest, breaking everything

test/jest-mocks.js

@@ -0,0 +1,14 @@
+// https://jestjs.io/docs/en/manual-mocks#mocking-methods-which-are-not-implemented-in-jsdom
+Object.defineProperty(window, 'matchMedia', {
+    writable: true,
+    value: jest.fn().mockImplementation(query => ({
+        matches: false,
+        media: query,
+        onchange: null,
+        addListener: jest.fn(), // deprecated
+        removeListener: jest.fn(), // deprecated
+        addEventListener: jest.fn(),
+        removeEventListener: jest.fn(),
+        dispatchEvent: jest.fn(),
+    })),
+});