feat: add WEBPACK_SERVE environment variable (#2027)

* tests: add test case for requirement

* feat: add WEBPACK_SERVE variable

* refactor: declare into variable

* feat: enforce use of env variable

* chore: update variable defination

* chore: update snapshots

packages/serve/__tests__/__snapshots__/parseArgs.test.ts.snap

@@ -11,6 +11,9 @@ Object {
   },
   "webpackArgs": Object {
     "color": true,
+    "env": Object {
+      "WEBPACK_SERVE": true,
+    },
     "hot": true,
   },
 }
@@ -39,6 +42,9 @@ Object {
   },
   "webpackArgs": Object {
     "color": true,
+    "env": Object {
+      "WEBPACK_SERVE": true,
+    },
     "mode": "development",
   },
 }

packages/serve/src/parseArgs.ts

@@ -39,6 +39,13 @@ export default function parseArgs(cli: WebpackCLIType, args: string[]): ArgsType
     const parsedWebpackArgs = cli.argParser(core, parsedDevServerArgs.unknownArgs, true, process.title);
     const webpackArgs = parsedWebpackArgs.opts;
 
+    // Add WEBPACK_SERVE environment variable
+    if (webpackArgs.env) {
+        webpackArgs.env.WEBPACK_SERVE = true;
+    } else {
+        webpackArgs.env = { WEBPACK_SERVE: true };
+    }
+
     // pass along the 'hot' argument to the dev server if it exists
     if (webpackArgs && webpackArgs.hot !== undefined) {
         devServerArgs['hot'] = webpackArgs.hot;

test/serve/serve-variable/serve-basic.test.js

@@ -0,0 +1,33 @@
+'use strict';
+
+const path = require('path');
+const getPort = require('get-port');
+const { runServe } = require('../../utils/test-utils');
+
+const testPath = path.resolve(__dirname);
+
+describe('serve variable', () => {
+    let port;
+
+    beforeEach(async () => {
+        port = await getPort();
+    });
+
+    const isWindows = process.platform === 'win32';
+
+    // TODO fix me on windows
+    if (isWindows) {
+        it('TODO: Fix on windows', () => {
+            expect(true).toBe(true);
+        });
+        return;
+    }
+
+    it('compiles without flags and export variable', async () => {
+        const { stdout, stderr } = await runServe(['--port', port], testPath);
+        expect(stdout).toContain('main.js');
+        expect(stdout).not.toContain('HotModuleReplacementPlugin');
+        expect(stderr).toHaveLength(0);
+        expect(stdout).toContain('PASS');
+    });
+});

test/serve/serve-variable/src/index.js

@@ -0,0 +1 @@
+console.log('hello world');

test/serve/serve-variable/webpack.config.js

@@ -0,0 +1,24 @@
+const isInProcess = process.env.WEBPACK_SERVE;
+
+class CustomTestPlugin {
+    constructor(isInEnvironment) {
+        this.isInEnvironment = isInEnvironment;
+    }
+    apply(compiler) {
+        compiler.hooks.done.tap('testPlugin', () => {
+            if (!isInProcess && this.isInEnvironment) {
+                console.log('PASS');
+            } else {
+                console.log('FAIL');
+            }
+        });
+    }
+}
+
+module.exports = (env) => {
+    return {
+        mode: 'development',
+        devtool: false,
+        plugins: [new CustomTestPlugin(env.WEBPACK_SERVE)],
+    };
+};