Move testing to ava

Fixes #181.

test/level.js

@@ -0,0 +1,52 @@
+import path from 'path';
+import test from 'ava';
+import execa from 'execa';
+import resolveFrom from 'resolve-from';
+
+// Spoof supports-color
+require.cache[resolveFrom(__dirname, 'supports-color')] = {
+	exports: {
+		level: 3,
+		hasBasic: true,
+		has256: true,
+		has16m: true
+	}
+};
+
+const m = require('..');
+
+test('don\'t output colors when manually disabled', t => {
+	const oldLevel = m.level;
+	m.level = 0;
+	t.is(m.red('foo'), 'foo');
+	m.level = oldLevel;
+});
+
+test('enable/disable colors based on overall chalk enabled property, not individual instances', t => {
+	const oldLevel = m.level;
+	m.level = 1;
+	const red = m.red;
+	t.is(red.level, 1);
+	m.level = 0;
+	t.is(red.level, m.level);
+	m.level = oldLevel;
+});
+
+test('propagate enable/disable changes from child colors', t => {
+	const oldLevel = m.level;
+	m.level = 1;
+	const red = m.red;
+	t.is(red.level, 1);
+	t.is(m.level, 1);
+	red.level = 0;
+	t.is(red.level, 0);
+	t.is(m.level, 0);
+	m.level = 1;
+	t.is(red.level, 1);
+	t.is(m.level, 1);
+	m.level = oldLevel;
+});
+
+test('disable colors if they are not supported', async t => {
+	t.is(await execa.stdout('node', [path.join(__dirname, '_fixture')]), 'test');
+});