feat: include next polyfils (including global fetch support) (#40)

Co-authored-by: Vadorequest <[email protected]>

src/__example-files__/uses-fetch.preval.ts

@@ -0,0 +1,10 @@
+import preval from 'next-plugin-preval';
+
+async function getDataViaFetch() {
+  const response = await fetch('https://example.com');
+  const html = await response.text();
+
+  return { html };
+}
+
+export default preval(getDataViaFetch());

src/loader.test.ts

@@ -112,6 +112,16 @@ describe('_prevalLoader', () => {
 
     expect(caught).toBe(true);
   });
+
+  it("polyfills fetch (and others) via require('next')", async () => {
+    const result = await _prevalLoader(
+      '',
+      require.resolve('./__example-files__/uses-fetch.preval.ts'),
+      {}
+    );
+
+    expect(result.includes('Example Domain')).toBe(true);
+  });
 });
 
 describe('loader', () => {

src/loader.ts

@@ -92,7 +92,7 @@ export async function _prevalLoader(
   const data = await (async () => {
     try {
       const mod = requireFromString(
-        `module.exports = require(${JSON.stringify(resource)})`,
+        `require('next');\nmodule.exports = require(${JSON.stringify(resource)})`,
         `${resource}.preval.js`
       );