fix(plugin): only minimize when used as minimizer

src/plugin.ts

@@ -97,13 +97,13 @@
 					? new SourceMapSource(
 						result.code,
 						asset.name,
 						result.map as any,
 						sourceAsString,
 						map as any,
 						true,
 					)
 					: new RawSource(result.code)
 			) as any,
 			{
 				...asset.info,
 				minimized: true,
@@ -129,18 +129,8 @@
 
 	const transform = implementation?.transform ?? defaultEsbuildTransform;
 
-	const hasGranularMinificationConfig = (
-		'minifyIdentifiers' in options
-		|| 'minifySyntax' in options
-		|| 'minifyWhitespace' in options
-	);
-
-	if (!hasGranularMinificationConfig) {
-		options.minify = true;
-	}
-
-	return {
+	const pluginInstance = {
 		apply(compiler: Compiler) {
 			if (!('format' in options)) {
 				const { target } = compiler.options;
 				const isWebTarget = (
@@ -162,6 +152,23 @@
 				}
 			}
 
+			/**
+			 * Enable minification by default if used in the minimizer array
+			 * unless further specified in the options
+			 */
+			const usedAsMinimizer = compiler.options.optimization?.minimizer?.includes?.(pluginInstance);
+			if (
+				usedAsMinimizer
+				&& !(
+					'minify' in options
+					|| 'minifyWhitespace' in options
+					|| 'minifyIdentifiers' in options
+					|| 'minifySyntax' in options
+				)
+			) {
+				options.minify = compiler.options.optimization?.minimize;
+			}
+
 			compiler.hooks.compilation.tap(pluginName, (compilation) => {
 				const meta = JSON.stringify({
 					name: 'esbuild-loader',
@@ -230,4 +237,6 @@
 			});
 		},
 	};
+
+	return pluginInstance;
 }

tests/specs/plugin.ts

@@ -9,7 +9,7 @@ import {
 	configureMiniCssExtractPlugin,
 } from '../utils.js';
 import * as fixtures from '../fixtures.js';
-import type { EsbuildPluginOptions } from '#esbuild-loader';
+import { EsbuildPlugin, type EsbuildPluginOptions } from '#esbuild-loader';
 
 const assertMinified = (code: string) => {
 	expect(code).not.toMatch(/\s{2,}/);
@@ -23,7 +23,72 @@ export default testSuite(({ describe }, webpack: typeof webpack4 | typeof webpac
 	const webpackIs4 = isWebpack4(webpack);
 
 	describe('Plugin', ({ test, describe }) => {
-		describe('Minify JS', ({ test }) => {
+		describe('Minify JS', ({ test, describe }) => {
+			describe('should not minify by default', ({ test }) => {
+				test('minimizer', async () => {
+					const built = await build(
+						fixtures.minification,
+						(config) => {
+							config.optimization = {
+								minimize: false,
+								minimizer: [
+									new EsbuildPlugin(),
+								],
+							};
+						},
+						webpack,
+					);
+
+					expect(built.stats.hasWarnings()).toBe(false);
+					expect(built.stats.hasErrors()).toBe(false);
+
+					const exportedFunction = built.require('/dist/');
+					expect(exportedFunction('hello world')).toBe('hello world');
+					expect(exportedFunction.toString()).toMatch(/\s{2,}/);
+				});
+
+				test('plugin', async () => {
+					const built = await build(
+						fixtures.minification,
+						(config) => {
+							config.plugins?.push(new EsbuildPlugin());
+						},
+						webpack,
+					);
+
+					expect(built.stats.hasWarnings()).toBe(false);
+					expect(built.stats.hasErrors()).toBe(false);
+
+					const exportedFunction = built.require('/dist/');
+					expect(exportedFunction('hello world')).toBe('hello world');
+					expect(exportedFunction.toString()).toMatch(/\s{2,}/);
+				});
+
+				test('plugin with minimize enabled', async () => {
+					const built = await build(
+						fixtures.minification,
+						(config) => {
+							config.optimization = {
+								minimize: true,
+
+								// Remove Terser
+								minimizer: [],
+							};
+
+							config.plugins?.push(new EsbuildPlugin());
+						},
+						webpack,
+					);
+
+					expect(built.stats.hasWarnings()).toBe(false);
+					expect(built.stats.hasErrors()).toBe(false);
+
+					const exportedFunction = built.require('/dist/');
+					expect(exportedFunction('hello world')).toBe('hello world');
+					expect(exportedFunction.toString()).toMatch(/\s{2,}/);
+				});
+			});
+
 			test('minify', async () => {
 				const built = await build(
 					fixtures.minification,