test: add basic "unit" test

Adds two tests for getWalletData function

src/api/getWallet.test.ts

@@ -0,0 +1,20 @@
+import { Status } from '@tatumio/tatum';
+import { getWalletData } from './getWallet';
+
+// TODO: mock Tatum library to get real unit tests
+
+test('should return error for non-existing address', async () => {
+  const result = await getWalletData('non-existing-address');
+  expect(result).toStrictEqual([Status.ERROR, null, null]);
+});
+
+test('should return valid response for existing address', async () => {
+  const result = await getWalletData('0xb794f5ea0ba39494ce839613fffba74279579268');
+  expect(result[0]).toBe(Status.SUCCESS);
+
+  expect(result[1]).toBeDefined();
+  expect(result[1][0].balance.length).toBeGreaterThan(0);
+
+  expect(result[2]).toBeDefined();
+  expect(result[2].length).toBe(10);
+});