Allow registering translations in the defaultConfig

packages/ckeditor5-core/src/editor/editor.ts

@@ -275,12 +275,13 @@ export default abstract class Editor extends ObservableMixin() {
 
 		const constructor = this.constructor as typeof Editor;
 
-		// Prefer the language passed as the argument to the constructor instead of the constructor's `defaultConfig`, if both are set.
-		const language = config.language || ( constructor.defaultConfig && constructor.defaultConfig.language );
-
 		// We don't pass translations to the config, because its behavior of splitting keys
 		// with dots (e.g. `resize.width` => `resize: { width }`) breaks the translations.
-		const { translations, ...rest } = config;
+		const { translations: defaultTranslations, ...defaultConfig } = constructor.defaultConfig || {};
+		const { translations = defaultTranslations, ...rest } = config;
+
+		// Prefer the language passed as the argument to the constructor instead of the constructor's `defaultConfig`, if both are set.
+		const language = config.language || defaultConfig.language;
 
 		this._context = config.context || new Context( { language, translations } );
 		this._context._addEditor( this, !config.context );
@@ -289,7 +290,7 @@ export default abstract class Editor extends ObservableMixin() {
 		// between editors and make the watchdog feature work correctly.
 		const availablePlugins = Array.from( constructor.builtinPlugins || [] );
 
-		this.config = new Config<EditorConfig>( rest, constructor.defaultConfig );
+		this.config = new Config<EditorConfig>( rest, defaultConfig );
 		this.config.define( 'plugins', availablePlugins );
 		this.config.define( this._context._getEditorConfig() );
 

packages/ckeditor5-core/tests/context.js

@@ -505,7 +505,7 @@ describe( 'Context', () => {
 		} );
 	} );
 
-	describe( 'translations', () => {
+	describe( 'config.translations', () => {
 		let editor, element;
 
 		beforeEach( () => {
@@ -546,6 +546,52 @@ describe( 'Context', () => {
 			expect( editor.locale.translations.pl.dictionary[ 'a.b' ] ).to.equal( 'value' );
 		} );
 	} );
+
+	describe( 'defaultConfig.translations', () => {
+		let editor, element;
+
+		beforeEach( () => {
+			element = document.createElement( 'div' );
+			document.body.appendChild( element );
+
+			class TestEditor extends ClassicTestEditor {}
+
+			TestEditor.defaultConfig = {
+				translations: {
+					pl: {
+						dictionary: {
+							bold: 'Pogrubienie',
+							'a.b': 'value'
+						}
+					}
+				}
+			};
+
+			return TestEditor
+				.create( element )
+				.then( _editor => {
+					editor = _editor;
+				} );
+		} );
+
+		afterEach( () => {
+			document.body.removeChild( element );
+
+			return editor.destroy();
+		} );
+
+		it( 'should not set translations in the config', () => {
+			expect( editor.config.get( 'translations' ) ).to.equal( undefined );
+		} );
+
+		it( 'should properly get translations with the key', () => {
+			expect( editor.locale.translations.pl.dictionary.bold ).to.equal( 'Pogrubienie' );
+		} );
+
+		it( 'should properly get translations with dot in the key', () => {
+			expect( editor.locale.translations.pl.dictionary[ 'a.b' ] ).to.equal( 'value' );
+		} );
+	} );
 } );
 
 function getPlugins( editor ) {

packages/ckeditor5-core/tests/editor/editor.js

@@ -177,6 +177,22 @@ describe( 'Editor', () => {
 			expect( editor.config.get( 'translations' ) ).to.equal( undefined );
 		} );
 
+		it( 'should use translations set as the defaultConfig option on the constructor', () => {
+			TestEditor.defaultConfig = {
+				translations: {
+					pl: {
+						dictionary: {
+							Bold: 'Pogrubienie'
+						}
+					}
+				}
+			};
+
+			const editor = new TestEditor();
+
+			expect( editor.config.get( 'translations' ) ).to.equal( undefined );
+		} );
+
 		it( 'should bind editing.view.document#isReadOnly to the editor#isReadOnly', () => {
 			const editor = new TestEditor();