fix: improve parsing of --env flag

packages/webpack-cli/lib/webpack-cli.js

@@ -373,6 +373,11 @@ class WebpackCLI {
             {
                 name: 'env',
                 type: (value, previous = {}) => {
+                    // for https://github.com/webpack/webpack-cli/issues/2642
+                    if (value.endsWith('=')) {
+                        value.concat('""');
+                    }
+
                     // This ensures we're only splitting by the first `=`
                     const [allKeys, val] = value.split(/=(.+)/, 2);
                     const splitKeys = allKeys.split(/\.(?!$)/);
@@ -389,7 +394,11 @@ class WebpackCLI {
                         }
 
                         if (index === splitKeys.length - 1) {
-                            prevRef[someKey] = val || true;
+                            if (typeof val === 'string') {
+                                prevRef[someKey] = val;
+                            } else {
+                                prevRef[someKey] = true;
+                            }
                         }
 
                         prevRef = prevRef[someKey];
@@ -1212,13 +1221,13 @@ class WebpackCLI {
             const defaultCommandToRun = getCommandName(buildCommandOptions.name);
             const hasOperand = typeof operands[0] !== 'undefined';
             const operand = hasOperand ? operands[0] : defaultCommandToRun;
-
+            const isHelpOption = typeof options.help !== 'undefined';
             const isHelpCommandSyntax = isCommand(operand, helpCommandOptions);
 
-            if (options.help || isHelpCommandSyntax) {
+            if (isHelpOption || isHelpCommandSyntax) {
                 let isVerbose = false;
 
-                if (options.help) {
+                if (isHelpOption) {
                     if (typeof options.help === 'string') {
                         if (options.help !== 'verbose') {
                             this.logger.error("Unknown value for '--help' option, please use '--help=verbose'");
@@ -1232,7 +1241,7 @@ class WebpackCLI {
                 this.program.forHelp = true;
 
                 const optionsForHelp = []
-                    .concat(options.help && hasOperand ? [operand] : [])
+                    .concat(isHelpOption && hasOperand ? [operand] : [])
                     // Syntax `webpack help [command]`
                     .concat(operands.slice(1))
                     // Syntax `webpack help [option]`
@@ -1243,9 +1252,12 @@ class WebpackCLI {
                 await outputHelp(optionsForHelp, isVerbose, isHelpCommandSyntax, program);
             }
 
-            if (options.version || isCommand(operand, versionCommandOptions)) {
+            const isVersionOption = typeof options.version !== 'undefined';
+            const isVersionCommandSyntax = isCommand(operand, versionCommandOptions);
+
+            if (isVersionOption || isVersionCommandSyntax) {
                 const optionsForVersion = []
-                    .concat(options.version ? [operand] : [])
+                    .concat(isVersionOption ? [operand] : [])
                     .concat(operands.slice(1))
                     .concat(unknown);
 

test/build/config/type/function-with-env/function-with-env.test.js

@@ -117,6 +117,36 @@ describe('function configuration', () => {
         expect(existsSync(resolve(__dirname, './dist/true.js'))).toBeTruthy();
     });
 
+    it('Supports empty string', async () => {
+        const { exitCode, stderr, stdout } = await run(__dirname, ['--env', `foo=''`]);
+
+        expect(exitCode).toBe(0);
+        expect(stderr).toBeFalsy();
+        expect(stdout).toBeTruthy();
+        // Should generate the appropriate files
+        expect(existsSync(resolve(__dirname, './dist/empty-string.js'))).toBeTruthy();
+    });
+
+    it('Supports empty string with multiple "="', async () => {
+        const { exitCode, stderr, stdout } = await run(__dirname, ['--env', `foo=bar=''`]);
+
+        expect(exitCode).toBe(0);
+        expect(stderr).toBeFalsy();
+        expect(stdout).toBeTruthy();
+        // Should generate the appropriate files
+        expect(existsSync(resolve(__dirname, './dist/new-empty-string.js'))).toBeTruthy();
+    });
+
+    it('Supports env variable with "=" at the end', async () => {
+        const { exitCode, stderr, stdout } = await run(__dirname, ['--env', `foo=`]);
+
+        expect(exitCode).toBe(0);
+        expect(stderr).toBeFalsy();
+        expect(stdout).toBeTruthy();
+        // Should generate the appropriate files
+        expect(existsSync(resolve(__dirname, './dist/equal-at-the-end.js'))).toBeTruthy();
+    });
+
     it('is able to understand multiple env flags', async () => {
         const { exitCode, stderr, stdout } = await run(__dirname, ['--env', 'isDev', '--env', 'verboseStats', '--env', 'envMessage']);
 

test/build/config/type/function-with-env/webpack.config.js

@@ -9,6 +9,30 @@ module.exports = (env) => {
             },
         };
     }
+    if (env.foo === `''`) {
+        return {
+            entry: './a.js',
+            output: {
+                filename: 'empty-string.js',
+            },
+        };
+    }
+    if (env.foo === `bar=''`) {
+        return {
+            entry: './a.js',
+            output: {
+                filename: 'new-empty-string.js',
+            },
+        };
+    }
+    if (env['foo=']) {
+        return {
+            entry: './a.js',
+            output: {
+                filename: 'equal-at-the-end.js',
+            },
+        };
+    }
     return {
         entry: './a.js',
         mode: 'development',

test/help/__snapshots__/help.test.js.snap.webpack4

@@ -28,6 +28,8 @@ exports[`help should log error for invalid command using the "--help" option 1`]
 
 exports[`help should log error for invalid flag with the "--help" option #2 1`] = `"[webpack-cli] Unknown value for '--help' option, please use '--help=verbose'"`;
 
+exports[`help should log error for invalid flag with the "--help" option #2 2`] = `"[webpack-cli] Unknown value for '--help' option, please use '--help=verbose'"`;
+
 exports[`help should log error for invalid flag with the "--help" option 1`] = `
 "[webpack-cli] Incorrect use of help
 [webpack-cli] Please use: 'webpack help [command] [option]' | 'webpack [command] --help'

test/help/__snapshots__/help.test.js.snap.webpack5

@@ -28,6 +28,8 @@ exports[`help should log error for invalid command using the "--help" option 1`]
 
 exports[`help should log error for invalid flag with the "--help" option #2 1`] = `"[webpack-cli] Unknown value for '--help' option, please use '--help=verbose'"`;
 
+exports[`help should log error for invalid flag with the "--help" option #2 2`] = `"[webpack-cli] Unknown value for '--help' option, please use '--help=verbose'"`;
+
 exports[`help should log error for invalid flag with the "--help" option 1`] = `
 "[webpack-cli] Incorrect use of help
 [webpack-cli] Please use: 'webpack help [command] [option]' | 'webpack [command] --help'

test/help/help.test.js

@@ -402,4 +402,12 @@ describe('help', () => {
         expect(stderr).toMatchSnapshot();
         expect(stdout).toBeFalsy();
     });
+
+    it('should log error for invalid flag with the "--help" option #2', async () => {
+        const { exitCode, stderr, stdout } = await run(__dirname, ['--help=']);
+
+        expect(exitCode).toBe(2);
+        expect(stderr).toMatchSnapshot();
+        expect(stdout).toBeFalsy();
+    });
 });