* add shim test

Author: Ethella

test/spec/utils/shim.spec.ts

@@ -0,0 +1,24 @@
+import atob from 'atob';
+
+test('#01: Shim overwrites undefined global atob', async () => {
+  globalThis.atob = undefined;
+
+  expect(globalThis.atob).toBeUndefined();
+
+  // eslint-disable-next-line global-require
+  require('../../../src/utils/shim');
+
+  expect(globalThis.atob).toBe(atob);
+});
+
+test('#02: Shim does not overwrite exisiting atob', async () => {
+  const dummyFunc = () => '';
+  globalThis.atob = dummyFunc;
+
+  expect(globalThis.atob).toBe(dummyFunc);
+
+  // eslint-disable-next-line global-require
+  require('../../../src/utils/shim');
+
+  expect(globalThis.atob).toBe(dummyFunc);
+});