Serve compressed assets in dist mode (dojo#214)

When serving in dist mode without memory watch, use express-static-gzip
instead of express.static in order to serve compressed build files.

README.md

@@ -250,7 +250,7 @@ An array of paths to [CLDR JSON](https://github.com/dojo/i18n#loading-cldr-data)
 
 #### `compression`: Array<'gzip' | 'brotli'>
 
-Options for compression when running in `dist` mode. Each array value represents a different algorithm, allowing both gzip and brotli builds to be output side-by-side.
+Options for compression when running in `dist` mode. Each array value represents a different algorithm, allowing both gzip and brotli builds to be output side-by-side. When used in conjunction with the `--serve` flag (in `dist` mode _without_ memory watch), the compressed files will be served, with brotli preferred over gzip when available.
 
 ### `externals`: object
 

package.json

@@ -110,6 +110,7 @@
     "css-loader": "0.28.7",
     "eventsource-polyfill": "0.9.6",
     "express": "4.16.2",
+    "express-static-gzip": "1.1.3",
     "extract-text-webpack-plugin": "3.0.2",
     "file-loader": "1.1.5",
     "globby": "7.1.1",

src/main.ts

@@ -12,6 +12,7 @@ import * as proxy from 'http-proxy-middleware';
 import * as history from 'connect-history-api-fallback';
 
 const pkgDir = require('pkg-dir');
+const expressStaticGzip = require('express-static-gzip');
 import devConfigFactory from './dev.config';
 import unitConfigFactory from './unit.config';
 import functionalConfigFactory from './functional.config';
@@ -170,7 +171,17 @@ function serve(config: webpack.Configuration, args: any): Promise<void> {
 
 	if (args.watch !== 'memory') {
 		const outputDir = (config.output && config.output.path) || process.cwd();
-		app.use(express.static(outputDir));
+		if (args.mode === 'dist' && Array.isArray(args.compression)) {
+			const useBrotli = args.compression.includes('brotli');
+			app.use(
+				expressStaticGzip(outputDir, {
+					enableBrotli: useBrotli,
+					orderPreference: useBrotli ? ['br'] : undefined
+				})
+			);
+		} else {
+			app.use(express.static(outputDir));
+		}
 	}
 
 	if (args.proxy) {

tests/unit/main.ts

@@ -50,6 +50,7 @@ describe('command', () => {
 			'./unit.config',
 			'connect-history-api-fallback',
 			'express',
+			'express-static-gzip',
 			'http-proxy-middleware',
 			'https',
 			'log-update',
@@ -540,6 +541,73 @@ describe('command', () => {
 				});
 		});
 
+		it('serves compressed files in dist mode', () => {
+			const expressStaticGzip = mockModule.getMock('express-static-gzip').ctor;
+			const main = mockModule.getModuleUnderTest().default;
+			const outputDir = '/output/dist';
+			const rc = {
+				mode: 'dist',
+				compression: ['gzip'],
+				serve: true
+			};
+			output.path = outputDir;
+			return main.run(getMockConfiguration(), rc).then(() => {
+				assert.isTrue(
+					expressStaticGzip.calledWith(outputDir, {
+						enableBrotli: false,
+						orderPreference: undefined
+					})
+				);
+			});
+		});
+
+		it('does not serve compressed files in dev mode', () => {
+			const expressStaticGzip = mockModule.getMock('express-static-gzip').ctor;
+			const main = mockModule.getModuleUnderTest().default;
+			const rc = {
+				mode: 'dev',
+				compression: ['gzip'],
+				serve: true
+			};
+			return main.run(getMockConfiguration(), rc).then(() => {
+				assert.isFalse(expressStaticGzip.called);
+			});
+		});
+
+		it('does not serve compressed files with memory watch', () => {
+			const expressStaticGzip = mockModule.getMock('express-static-gzip').ctor;
+			const main = mockModule.getModuleUnderTest().default;
+			const rc = {
+				mode: 'dist',
+				compression: ['gzip'],
+				serve: true,
+				watch: 'memory'
+			};
+			return main.run(getMockConfiguration(), rc).then(() => {
+				assert.isFalse(expressStaticGzip.called);
+			});
+		});
+
+		it('favors brotli over gzip', () => {
+			const expressStaticGzip = mockModule.getMock('express-static-gzip').ctor;
+			const main = mockModule.getModuleUnderTest().default;
+			const outputDir = '/output/dist';
+			const rc = {
+				mode: 'dist',
+				compression: ['gzip', 'brotli'],
+				serve: true
+			};
+			output.path = outputDir;
+			return main.run(getMockConfiguration(), rc).then(() => {
+				assert.isTrue(
+					expressStaticGzip.calledWith(outputDir, {
+						enableBrotli: true,
+						orderPreference: ['br']
+					})
+				);
+			});
+		});
+
 		describe('https', () => {
 			it('starts an https server if key and cert are available', () => {
 				const main = mockModule.getModuleUnderTest().default;