init commit,

99_references/blank-ionic-react/src/setupTests.ts

@@ -0,0 +1,14 @@
+// jest-dom adds custom jest matchers for asserting on DOM nodes.
+// allows you to do things like:
+// expect(element).toHaveTextContent(/react/i)
+// learn more: https://github.com/testing-library/jest-dom
+import '@testing-library/jest-dom/extend-expect';
+
+// Mock matchmedia
+window.matchMedia = window.matchMedia || function() {
+  return {
+      matches: false,
+      addListener: function() {},
+      removeListener: function() {}
+  };
+};