fix(graphql): fix ESM build (#1318)

Use file extensions for imports

packages/graphql/rollup.config.mjs

@@ -7,7 +7,7 @@ import { createConfig } from '../../shared/rollup.config.mjs';
 export default {
   ...createConfig({
     pkg: JSON.parse(readFileSync(new URL('./package.json', import.meta.url), 'utf8')),
-    external: ['graphql-tag/loader']
+    external: ['graphql-tag/loader.js']
   }),
   input: 'src/index.js',
   plugins: [buble()]

packages/graphql/src/index.js

@@ -1,5 +1,5 @@
 import { createFilter } from '@rollup/pluginutils';
-import loader from 'graphql-tag/loader';
+import loader from 'graphql-tag/loader.js';
 
 import { toESModules } from './toESModules';
 

packages/graphql/test/test.js

@@ -1,9 +1,9 @@
 const test = require('ava');
 const { rollup } = require('rollup');
 
-const { testBundle } = require('../../../util/test');
+const graphql = require('current-package');
 
-const graphql = require('..');
+const { testBundle } = require('../../../util/test');
 
 require('source-map-support').install();
 

packages/graphql/test/test.mjs

@@ -0,0 +1,22 @@
+import { fileURLToPath } from 'url';
+
+import test from 'ava';
+import { rollup } from 'rollup';
+
+import graphql from 'current-package';
+
+import { testBundle } from '../../../util/test.js';
+
+test.beforeEach(() => process.chdir(fileURLToPath(new URL('.', import.meta.url))));
+
+test('works as an ES module', async (t) => {
+  const bundle = await rollup({
+    input: 'fixtures/basic/index.js',
+    plugins: [graphql()]
+  });
+
+  const { module } = await testBundle(t, bundle);
+
+  t.truthy('doc' in module.exports);
+  t.is(module.exports.doc.kind, 'Document');
+});