Implement writeBundle hook

docs/05-plugins.md

@@ -90,7 +90,7 @@ Cf. [`output.banner/output.footer`](guide/en#output-banner-output-footer).
 #### `generateBundle`
 Type: `(options: OutputOptions, bundle: { [fileName: string]: AssetInfo | ChunkInfo }, isWrite: boolean) => void | Promise<void>`
 
-Called at the end of `bundle.generate()` or `bundle.write()`. `bundle` provides the full list of files being written or generated along with their details:
+Called at the end of `bundle.generate()` or immediately before the files are written in `bundle.write()`. To modify the files after they have been written, use the [`writeBundle`](guide/en#writebundle) hook. `bundle` provides the full list of files being written or generated along with their details:
 
 ```
 // AssetInfo
@@ -176,6 +176,11 @@ Type: `(id: string) => void`
 
 Notifies a plugin whenever rollup has detected a change to a monitored file in `--watch` mode.
 
+#### `writeBundle`
+Type: `( bundle: { [fileName: string]: AssetInfo | ChunkInfo }) => void | Promise<void>`
+
+Called only at the end of `bundle.write()` once all files have been written. Similar to the [`generateBundle`](guide/en#generatebundle) hook, `bundle` provides the full list of files being written along with their details.
+
 ### Deprecated
 
 ☢️ These hooks have been deprecated and may be removed in a future Rollup version.

src/rollup/index.ts

@@ -319,7 +319,9 @@ export default function rollup(rawInputOptions: GenericConfigObject): Promise<Ro
 								Object.keys(bundle).map(chunkId => {
 									return writeOutputFile(graph, result, bundle[chunkId], outputOptions);
 								})
-							).then(() => createOutput(bundle));
+							)
+								.then(() => graph.pluginDriver.hookSeq('writeBundle', [bundle]))
+								.then(() => createOutput(bundle));
 						});
 					})
 				};

src/rollup/types.d.ts

@@ -212,6 +212,7 @@ export interface Plugin {
 		bundle: OutputBundle,
 		isWrite: boolean
 	) => void | Promise<void>;
+	writeBundle?: (this: PluginContext, bundle: OutputBundle) => void | Promise<void>;
 	intro?: AddonHook;
 	load?: LoadHook;
 	name: string;

test/hooks/index.js

@@ -787,6 +787,7 @@ module.exports = input;
 					}),
 					{
 						generateBundle(options, outputBundle, isWrite) {
+							assert.strictEqual(isWrite, false);
 							const chunk = outputBundle['input.js'];
 
 							// can detect that b has been tree-shaken this way
@@ -802,9 +803,37 @@ module.exports = input;
 					}
 				]
 			})
-			.then(bundle => {
-				return bundle.generate({ format: 'es' });
-			});
+			.then(bundle => bundle.generate({ format: 'es' }));
+	});
+
+	it('supports writeBundle hook', () => {
+		const file = path.join(__dirname, 'tmp/bundle.js');
+		let bundle;
+		let callCount = 0;
+		return rollup
+			.rollup({
+				input: 'input',
+				plugins: [
+					loader({
+						input: `export { a as default } from 'dep';`,
+						dep: `export var a = 1; export var b = 2;`
+					}),
+					{
+						generateBundle(options, outputBundle, isWrite) {
+							bundle = outputBundle;
+							assert.strictEqual(isWrite, true);
+						}
+					},
+					{
+						writeBundle(outputBundle) {
+							assert.deepStrictEqual(outputBundle, bundle);
+							callCount++;
+						}
+					}
+				]
+			})
+			.then(bundle => bundle.write({ format: 'esm', file }))
+			.then(() => assert.strictEqual(callCount, 1));
 	});
 
 	it('supports this.cache for plugins', () => {