feat: implement the "fastly" condition (#660)

Author: Guy Bedford

integration-tests/cli/build-config.test.js

@@ -0,0 +1,25 @@
+import test from 'brittle';
+import { getBinPath } from 'get-bin-path'
+import { prepareEnvironment } from '@jakechampion/cli-testing-library';
+
+const cli = await getBinPath()
+
+test('should build the fastly condition', async function (t) {
+    const { execute, cleanup, writeFile, exists, path } = await prepareEnvironment();
+    t.teardown(async function () {
+        await cleanup();
+    });
+
+    await writeFile('./index.js', `import '#test';`)
+    await writeFile('./test.js', `addEventListener('fetch', function(){})`)
+    await writeFile('./package.json', `{ "type": "module", "imports": { "#test": { "fastly": "./test.js" } } }`)
+    
+    t.is(await exists('./app.wasm'), false)
+
+    const { code, stdout, stderr } = await execute(process.execPath, `${cli} ${path}/index.js ${path}/app.wasm`);
+
+    t.is(await exists('./app.wasm'), true)
+    t.alike(stdout, []);
+    t.alike(stderr, []);
+    t.is(code, 0);
+});

src/bundle.js

@@ -44,6 +44,7 @@ export const allowDynamicBackends = Object.getOwnPropertyDescriptor(globalThis.f
 
 export async function bundle(input) {
   return await build({
+    conditions: ['fastly'],
     entryPoints: [input],
     bundle: true,
     write: false,