fix: warn about merge config resolution cases (#1674)

* fix: show warning about merge config resolution cases

* fix: do not fallback to base config in merge

* fix: do not fallback to base config in merge

* fix: remove fallback to base config

* fix: do not fallback to base config

* feat: add MergeError calss

* feat: add MergeError class

* tests: add tests for merge

* tests: add more merge tests

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

@@ -1,8 +1,10 @@
 const { existsSync } = require('fs');
 const { resolve, sep, dirname, parse } = require('path');
+const webpackMerge = require('webpack-merge');
 const { extensions, jsVariants } = require('interpret');
 const GroupHelper = require('../utils/GroupHelper');
 const rechoir = require('rechoir');
+const MergeError = require('../utils/errors/MergeError');
 
 // Order defines the priority, in increasing order
 // example - config file lookup will be in order of .webpack/webpack.config.development.js -> webpack.config.development.js -> webpack.config.js
@@ -84,6 +86,7 @@ class ConfigGroup extends GroupHelper {
         const newOptionsObject = {
             outputOptions: {},
             options: {},
+            processingMessageBuffer: [],
         };
 
         if (!moduleObj) {
@@ -161,22 +164,18 @@ class ConfigGroup extends GroupHelper {
         if (Object.keys(this.args).some((arg) => arg === 'merge')) {
             const { merge } = this.args;
 
-            const newConfigPath = this.resolveFilePath(merge, 'webpack.base.js');
-            if (newConfigPath) {
-                const configFiles = getConfigInfoFromFileName(newConfigPath);
-                if (!configFiles.length) {
-                    this.opts.processingMessageBuffer.push({
-                        lvl: 'warn',
-                        msg: 'Could not find file to merge configuration with...',
-                    });
-                    return;
-                }
-                const foundConfig = configFiles[0];
-                const resolvedConfig = this.requireConfig(foundConfig);
-                const newConfigurationsObject = await this.finalize(resolvedConfig);
-                const webpackMerge = require('webpack-merge');
-                this.opts['options'] = webpackMerge(this.opts['options'], newConfigurationsObject.options);
+            // try resolving merge config
+            const newConfigPath = this.resolveFilePath(merge);
+
+            if (!newConfigPath) {
+                throw new MergeError("The supplied merge config doesn't exist.");
             }
+
+            const configFiles = getConfigInfoFromFileName(newConfigPath);
+            const foundConfig = configFiles[0];
+            const resolvedConfig = this.requireConfig(foundConfig);
+            const newConfigurationsObject = await this.finalize(resolvedConfig);
+            this.opts['options'] = webpackMerge(this.opts['options'], newConfigurationsObject.options);
         }
     }
 

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

@@ -47,7 +47,8 @@ class GroupHelper {
         const configPathExists = predefinedConfigPath ? existsSync(predefinedConfigPath) : undefined;
 
         if (!configPathExists) {
-            const LOOKUP_PATHS = [`${filename}`, `src/${filename}`, defaultValue, `src/${defaultValue}`];
+            const LOOKUP_PATHS = [`${filename}`, `src/${filename}`, ...(defaultValue ? [defaultValue, `src/${defaultValue}`] : [])];
+
             if (filename) {
                 LOOKUP_PATHS.unshift(filename);
             }

packages/webpack-cli/lib/utils/errors/MergeError.js

@@ -0,0 +1,10 @@
+class MergeError extends Error {
+    constructor(message) {
+        super(message);
+        this.name = 'MergeError';
+        // No need to show stack trace for known errors
+        this.stack = '';
+    }
+}
+
+module.exports = MergeError;

test/merge/config-absent/merge-config-absent.test.js

@@ -0,0 +1,22 @@
+'use strict';
+
+const fs = require('fs');
+const { join } = require('path');
+
+const { run } = require('../../utils/test-utils');
+
+describe('merge flag configuration', () => {
+    it('Show warning message when the merge config is absent', () => {
+        // 2.js doesn't exist, let's try merging with it
+        const { stdout, stderr } = run(__dirname, ['--config', './1.js', '--merge', './2.js'], false);
+
+        // Since the process will exit, nothing on stdout
+        expect(stdout).toBeFalsy();
+        // Confirm that the user is notified
+        expect(stderr).toContain(`MergeError: The supplied merge config doesn't exist.`);
+        // Default config would be used
+        expect(fs.existsSync(join(__dirname, './dist/merged.js'))).toBeFalsy();
+        // Since the process will exit so no compilation will be done
+        expect(fs.existsSync(join(__dirname, './dist/main.js'))).toBeFalsy();
+    });
+});

test/merge/config-absent/some_entry.js

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

test/merge/config/1.js

@@ -1,3 +1,6 @@
 module.exports = {
-    entry: './some_entry.js',
+    entry: './old_entry.js',
+    output: {
+        filename: 'badfile.js',
+    },
 };

test/merge/config/2.js

@@ -1,4 +1,5 @@
 module.exports = {
+    entry: './some_entry.js',
     output: {
         filename: 'merged.js',
     },

test/merge/config/merge-config.test.js

@@ -15,4 +15,13 @@ describe('merge flag configuration', () => {
             done();
         });
     });
+    it('merges two configurations together with flag alias', (done) => {
+        const { stdout } = run(__dirname, ['--config', './1.js', '-m', './2.js'], false);
+        expect(stdout).toContain('merged.js');
+        stat(resolve(__dirname, './dist/merged.js'), (err, stats) => {
+            expect(err).toBe(null);
+            expect(stats.isFile()).toBe(true);
+            done();
+        });
+    });
 });