feat(run): add input option (#1699)

* chore(run): add test for multiple entry points

* refactor(run): extract reusable consts from a test

* feat(run): add `input` option

Author: mkantor

packages/run/README.md

@@ -83,6 +83,13 @@ Default: `false`
 
 If `true`, instructs the plugin to listen to `stdin` for the sequences listed below followed by enter (carriage return).
 
+### `input`
+
+Type: `String`<br>
+Default: `null`
+
+Specifies the entry point this plugin will use. Not necessary if you only have a single entry point.
+
 #### `stdin` Input Actions
 
 When this option is enabled, `stdin` will listen for the following input and perform the associated action:

packages/run/src/index.ts

@@ -12,6 +12,7 @@ export default function run(opts: RollupRunOptions = {}): Plugin {
 
   const args = opts.args || [];
   const allowRestarts = opts.allowRestarts || false;
+  const overrideInput = opts.input;
   const forkOptions = opts.options || opts;
   delete (forkOptions as RollupRunOptions).args;
   delete (forkOptions as RollupRunOptions).allowRestarts;
@@ -20,7 +21,7 @@ export default function run(opts: RollupRunOptions = {}): Plugin {
     name: 'run',
 
     buildStart(options) {
-      let inputs = options.input;
+      let inputs = overrideInput ?? options.input;
 
       if (typeof inputs === 'string') {
         inputs = [inputs];
@@ -31,7 +32,9 @@ export default function run(opts: RollupRunOptions = {}): Plugin {
       }
 
       if (inputs.length > 1) {
-        throw new Error(`@rollup/plugin-run only works with a single entry point`);
+        throw new Error(
+          `@rollup/plugin-run must have a single entry point; consider setting the \`input\` option`
+        );
       }
 
       input = resolve(inputs[0]);

packages/run/test/test.js

@@ -15,12 +15,14 @@ const sinon = require('sinon');
 const run = require('../');
 
 const cwd = join(__dirname, 'fixtures/');
-const file = join(cwd, 'output/bundle.js');
+const outputDir = join(cwd, 'output');
+const file = join(outputDir, 'bundle.js');
 const input = join(cwd, 'input.js');
 
 process.chdir(cwd);
 
 const outputOptions = { file, format: 'cjs' };
+const outputDirOptions = { dir: outputDir, format: 'cjs' };
 
 let mockChildProcess;
 test.before(() => {
@@ -62,8 +64,7 @@ test('checks entry point facade module', async (t) => {
     preserveEntrySignatures: 'strict',
     plugins: [run()]
   });
-  const outputDir = join(cwd, 'output');
-  await bundle.write({ dir: outputDir, format: 'cjs' });
+  await bundle.write(outputDirOptions);
   t.true(mockChildProcess.calledWithExactly(join(outputDir, 'index.js'), [], {}));
 });
 
@@ -97,6 +98,40 @@ test('throws an error when bundle is not written to disk', async (t) => {
   );
 });
 
+test('throws an error when input option is invalid', async (t) => {
+  const testInput = join(cwd, 'change-detect-input.js');
+  const bundle = await rollup({
+    input: [input, testInput],
+    plugins: [run({ input: 'something that is not an input' })]
+  });
+  await t.throwsAsync(
+    async () => {
+      await bundle.write(outputDirOptions);
+    },
+    {
+      instanceOf: Error,
+      message: '@rollup/plugin-run could not find output chunk'
+    }
+  );
+});
+
+test('throws an error when there are multiple entry points', async (t) => {
+  const testInput = join(cwd, 'change-detect-input.js');
+  await t.throwsAsync(
+    async () => {
+      await rollup({
+        input: [input, testInput],
+        plugins: [run()]
+      });
+    },
+    {
+      instanceOf: Error,
+      message:
+        '@rollup/plugin-run must have a single entry point; consider setting the `input` option'
+    }
+  );
+});
+
 test('detects changes - forks a new child process and kills older process', async (t) => {
   // eslint-disable-next-line no-shadow
   const testInput = join(cwd, 'change-detect-input.js');
@@ -120,6 +155,16 @@ test('allow the allowRestart option', async (t) => {
   t.true(mockChildProcess.calledWithExactly(outputOptions.file, [], {}));
 });
 
+test('allow the input option', async (t) => {
+  const testInput = join(cwd, 'change-detect-input.js');
+  const bundle = await rollup({
+    input: [input, testInput],
+    plugins: [run({ input })]
+  });
+  await bundle.write(outputDirOptions);
+  t.true(mockChildProcess.calledWithExactly(join(outputDir, 'input.js'), [], { input }));
+});
+
 test.after(async () => {
   await del(['output']);
 });

packages/run/types/index.d.ts

@@ -6,6 +6,7 @@ export interface RollupRunOptions extends ForkOptions {
   args?: readonly string[];
   options?: ForkOptions;
   allowRestarts?: boolean;
+  input?: string;
 }
 
 /**