Improve ".configureBabel()" and ".configureBabelPresetEnv()" calls detection while validating Babel configuration

Author: Kocal

lib/WebpackConfig.js

@@ -149,8 +149,10 @@ class WebpackConfig {
         this.stylusLoaderOptionsCallback = () => {};
         /** @type {OptionsCallback<object>} */
         this.babelConfigurationCallback = () => {};
+        this._configureBabelCalled = false;
         /** @type {OptionsCallback<object>} */
         this.babelPresetEnvOptionsCallback = () => {};
+        this._configureBabelPresetEnvCalled = false;
         /** @type {OptionsCallback<object>} */
         this.babelReactPresetOptionsCallback = () => {};
         /** @type {OptionsCallback<object>} */
@@ -473,6 +475,7 @@ class WebpackConfig {
         }
 
         this.babelConfigurationCallback = callback || (() => {});
+        this._configureBabelCalled = callback !== null && callback !== undefined;
 
         // Whitelist some options that can be used even if there
         // is an external Babel config. The other ones won't be
@@ -546,6 +549,7 @@ class WebpackConfig {
         }
 
         this.babelPresetEnvOptionsCallback = callback;
+        this._configureBabelPresetEnvCalled = true;
     }
 
     /**

lib/config-generator.js

@@ -163,16 +163,8 @@ class ConfigGenerator {
 
         // Check from configureBabel(): if a callback was provided and an
         // external Babel config exists, that's an error.
-        if (this.webpackConfig.babelConfigurationCallback &&
-            this.webpackConfig.babelConfigurationCallback !== (() => {}).toString &&
-            babelRcFileExists) {
-            // The callback is non-default only when the user explicitly provided one
-            // We stored the original callback, so check if it's not the default no-op
-            const cb = this.webpackConfig.babelConfigurationCallback;
-            const isDefault = cb.toString() === (() => {}).toString();
-            if (!isDefault) {
-                throw new Error('The "callback" argument of configureBabel() will not be used because your app already provides an external Babel configuration (e.g. a ".babelrc" or "babel.config.js" file or "babel" key in "package.json"). Use null as the first argument to remove this error.');
-            }
+        if (this.webpackConfig._configureBabelCalled && babelRcFileExists) {
+            throw new Error('The "callback" argument of configureBabel() will not be used because your app already provides an external Babel configuration (e.g. a ".babelrc" or "babel.config.js" file or "babel" key in "package.json"). Use null as the first argument to remove this error.');
         }
 
         // Check from configureBabel(): warn about options that won't be applied
@@ -187,14 +179,10 @@ class ConfigGenerator {
             }
         }
 
-        // Check from configureBabelPresetEnv(): if a non-default callback was
-        // provided and an external Babel config exists, that's an error.
-        if (babelRcFileExists) {
-            const presetEnvCb = this.webpackConfig.babelPresetEnvOptionsCallback;
-            const isPresetEnvDefault = presetEnvCb.toString() === (() => {}).toString();
-            if (!isPresetEnvDefault) {
-                throw new Error('The "callback" argument of configureBabelPresetEnv() will not be used because your app already provides an external Babel configuration (e.g. a ".babelrc" or "babel.config.js" file or "babel" key in "package.json").');
-            }
+        // Check from configureBabelPresetEnv(): if configureBabelPresetEnv()
+        // was called and an external Babel config exists, that's an error.
+        if (this.webpackConfig._configureBabelPresetEnvCalled && babelRcFileExists) {
+            throw new Error('The "callback" argument of configureBabelPresetEnv() will not be used because your app already provides an external Babel configuration (e.g. a ".babelrc" or "babel.config.js" file or "babel" key in "package.json").');
         }
     }