From 1fa937468fd6033f8d8ec10e800d671fc1d01f7e Mon Sep 17 00:00:00 2001
From: Tomer Aberbach <tomeraberbach@gmail.com>
Date: Sun, 5 Jul 2020 01:18:23 -0400
Subject: [PATCH] feat: make options hook async (#3660)

---
 docs/05-plugin-development.md                 |  2 +-
 src/rollup/rollup.ts                          | 15 +++++----
 .../samples/options-async-hook/_config.js     | 33 +++++++++++++++++++
 .../samples/options-async-hook/file.txt       |  1 +
 .../samples/options-async-hook/unused.js      |  1 +
 .../samples/options-async-hook/used.js        |  1 +
 6 files changed, 46 insertions(+), 7 deletions(-)
 create mode 100644 test/function/samples/options-async-hook/_config.js
 create mode 100644 test/function/samples/options-async-hook/file.txt
 create mode 100644 test/function/samples/options-async-hook/unused.js
 create mode 100644 test/function/samples/options-async-hook/used.js

diff --git a/docs/05-plugin-development.md b/docs/05-plugin-development.md
index 4cf9ec6e0ff..2610c7f119c 100644
--- a/docs/05-plugin-development.md
+++ b/docs/05-plugin-development.md
@@ -124,7 +124,7 @@ You can use [`this.getModuleInfo`](guide/en/#thisgetmoduleinfomoduleid-string--m
 
 #### `options`
 Type: `(options: InputOptions) => InputOptions | null`<br>
-Kind: `sync, sequential`<br>
+Kind: `async, sequential`<br>
 Previous Hook: This is the first hook of the build phase.<br>
 Next Hook: [`buildStart`](guide/en/#buildstart)
 
diff --git a/src/rollup/rollup.ts b/src/rollup/rollup.ts
index fa732647c43..7224d24a389 100644
--- a/src/rollup/rollup.ts
+++ b/src/rollup/rollup.ts
@@ -32,7 +32,7 @@ export async function rollupInternal(
 	rawInputOptions: GenericConfigObject,
 	watcher: RollupWatcher | null
 ): Promise<RollupBuild> {
-	const { options: inputOptions, unsetOptions: unsetInputOptions } = getInputOptions(
+	const { options: inputOptions, unsetOptions: unsetInputOptions } = await getInputOptions(
 		rawInputOptions,
 		watcher !== null
 	);
@@ -89,28 +89,31 @@ export async function rollupInternal(
 	return result;
 }
 
-function getInputOptions(
+async function getInputOptions(
 	rawInputOptions: GenericConfigObject,
 	watchMode: boolean
-): { options: NormalizedInputOptions; unsetOptions: Set<string> } {
+): Promise<{ options: NormalizedInputOptions; unsetOptions: Set<string> }> {
 	if (!rawInputOptions) {
 		throw new Error('You must supply an options object to rollup');
 	}
 	const rawPlugins = ensureArray(rawInputOptions.plugins) as Plugin[];
 	const { options, unsetOptions } = normalizeInputOptions(
-		rawPlugins.reduce(applyOptionHook(watchMode), rawInputOptions)
+		await rawPlugins.reduce(applyOptionHook(watchMode), Promise.resolve(rawInputOptions))
 	);
 	normalizePlugins(options.plugins, ANONYMOUS_PLUGIN_PREFIX);
 	return { options, unsetOptions };
 }
 
 function applyOptionHook(watchMode: boolean) {
-	return (inputOptions: GenericConfigObject, plugin: Plugin): GenericConfigObject => {
+	return async (
+		inputOptions: Promise<GenericConfigObject>,
+		plugin: Plugin
+	): Promise<GenericConfigObject> => {
 		if (plugin.options)
 			return (
 				(plugin.options.call(
 					{ meta: { rollupVersion, watchMode } },
-					inputOptions
+					await inputOptions
 				) as GenericConfigObject) || inputOptions
 			);
 
diff --git a/test/function/samples/options-async-hook/_config.js b/test/function/samples/options-async-hook/_config.js
new file mode 100644
index 00000000000..07426baa8ed
--- /dev/null
+++ b/test/function/samples/options-async-hook/_config.js
@@ -0,0 +1,33 @@
+const assert = require('assert');
+const { promises: fs } = require('fs');
+
+module.exports = {
+	description: 'resolves promises between sequential options hooks',
+	options: {
+		input: 'super-unused',
+		treeshake: false,
+		plugins: [
+			{
+				name: 'test-plugin-1',
+				async options(options) {
+					assert.deepStrictEqual(JSON.parse(JSON.stringify(options)), {
+						input: 'super-unused',
+						plugins: [{ name: 'test-plugin-1' }, { name: 'test-plugin-2' }],
+						strictDeprecations: true,
+						treeshake: false
+					});
+					return Object.assign({}, options, {
+						input: (await fs.readFile('file.txt', 'utf8')).trim()
+					});
+				}
+			},
+			{
+				name: 'test-plugin-2',
+				options(options) {
+					assert.strictEqual(options.input, 'unused');
+					return Object.assign({}, options, { input: 'used' });
+				}
+			}
+		]
+	}
+};
diff --git a/test/function/samples/options-async-hook/file.txt b/test/function/samples/options-async-hook/file.txt
new file mode 100644
index 00000000000..b2c475fedd4
--- /dev/null
+++ b/test/function/samples/options-async-hook/file.txt
@@ -0,0 +1 @@
+unused
diff --git a/test/function/samples/options-async-hook/unused.js b/test/function/samples/options-async-hook/unused.js
new file mode 100644
index 00000000000..a9244a453fb
--- /dev/null
+++ b/test/function/samples/options-async-hook/unused.js
@@ -0,0 +1 @@
+throw new Error('Not executed');
diff --git a/test/function/samples/options-async-hook/used.js b/test/function/samples/options-async-hook/used.js
new file mode 100644
index 00000000000..7a4e8a723a4
--- /dev/null
+++ b/test/function/samples/options-async-hook/used.js
@@ -0,0 +1 @@
+export default 42;