Test Forecast module construction

src/index.js

@@ -2,7 +2,7 @@ const axios = require('axios');
 const stringifyDates = require('./stringifyDates');
 
 class Forecast {
-	constructor({ accountId, token }) {
+	constructor({ accountId, token } = {}) {
 		if (!accountId || !token) {
 			throw new Error(
 				'Forecast module requires accountId and token to be configured.'

src/index.test.js

@@ -1,5 +1,41 @@
+const axios = require('axios');
+const Forecast = require('./index');
+
+jest.mock('axios');
+
+const MOCK_CREDENTIALS = {
+	accountId: 'mock__accountId',
+	token: 'mock__token',
+};
+
 describe('forecast-promise', () => {
-	it('passes dummy test', () => {
-		expect(true).toBe(true);
+	it('crashes with no input', () => {
+		expect(() => new Forecast()).toThrow(
+			'Forecast module requires accountId and token to be configured.'
+		);
+	});
+
+	it('crashes with only one input', () => {
+		expect(
+			() => new Forecast({ accountId: MOCK_CREDENTIALS.accountId })
+		).toThrow('Forecast module requires accountId and token to be configured.');
+
+		expect(() => new Forecast({ token: MOCK_CREDENTIALS.token })).toThrow(
+			'Forecast module requires accountId and token to be configured.'
+		);
+	});
+
+	it('instantiates axios with valid input', () => {
+		axios.create.mockImplementation(args => args);
+		const f = new Forecast(MOCK_CREDENTIALS);
+
+		expect(f.instance).toEqual({
+			baseURL: 'https://api.forecastapp.com/',
+			headers: {
+				Authorization: `Bearer ${MOCK_CREDENTIALS.token}`,
+				'Forecast-Account-Id': MOCK_CREDENTIALS.accountId,
+				'User-Agent': 'https://www.npmjs.com/package/forecast-promise',
+			},
+		});
 	});
 });