test(core): add structural test

Author: marionebl

@commitlint/core/src/index.test.js

@@ -0,0 +1,21 @@
+import test from 'ava';
+
+test('exports format method', t => {
+	const {format} = require('.');
+	t.is(typeof format, 'function');
+});
+
+test('exports lint method', t => {
+	const {lint} = require('.');
+	t.is(typeof lint, 'function');
+});
+
+test('exports load method', t => {
+	const {load} = require('.');
+	t.is(typeof load, 'function');
+});
+
+test('exports read method', t => {
+	const {read} = require('.');
+	t.is(typeof read, 'function');
+});