Add failed test

test/override-promise.js

@@ -0,0 +1,17 @@
+import test from 'ava';
+
+// Can't use `test.before`, maybe because `ava` need `Promise`
+// Can't use `import('..')` too, unknown reason
+const nativePromise = Promise;
+global.Promise = class BrokenPromise {
+	then() {
+		throw new Error('error');
+	}
+};
+const execa = require('..');
+global.Promise = nativePromise;
+
+test('Should work with third party Promise', async t => {
+	const {stdout} = await execa('echo execa');
+	t.is(stdout, 'execa');
+});