random: Add tests

resolving #4

test/random.test.ts

@@ -0,0 +1,27 @@
+import * as request from '../source/request';
+import wiki from "../source/index";
+import { summaryJson } from './samples';
+const requestMock = jest.spyOn(request, "makeRestRequest");
+
+afterAll(() => {
+    requestMock.mockRestore();
+})
+
+test('Throws error if response is error', async () => {
+    requestMock.mockImplementation(async () => { throw new Error("This is an error") });
+    const err = async () => { await wiki.random("some_arg") };
+    expect(err).rejects.toThrowError(Error);
+});
+
+test('Returns summary of random article', async () => {
+    requestMock.mockImplementation(async () => { return summaryJson });
+    const result = await wiki.random("summary");
+    expect(result).toStrictEqual(summaryJson);
+});
+
+test('Request includes arg provided to method', async () => {
+    requestMock.mockImplementation(async () => { return summaryJson });
+    const result = await wiki.random("summary");
+    expect(result).toStrictEqual(summaryJson);
+    expect(requestMock).toBeCalledWith(`page/random/summary`);
+});