[AAE-12146] Update getFeature typings (#8167)

* [AAE-11463] Update getFeature typings

* added tests

lib/extensions/src/lib/services/extension.service.spec.ts

@@ -57,6 +57,43 @@ describe('ExtensionService', () => {
         expect(service.setup).toHaveBeenCalledWith(blankConfig);
     });
 
+    describe('getFeature', () => {
+        it('should return array if seached feature is an array', async () => {
+            const searchedArrayFeature = [{ test: 'test' }];
+
+            service.setup({
+                ...blankConfig,
+                features: {
+                    searchedArrayFeature
+                }
+            });
+
+            const requestedFeatue = service.getFeature('searchedArrayFeature');
+            expect(requestedFeatue).toEqual(searchedArrayFeature);
+        });
+
+        it('should return object if seached feature is an object', async () => {
+            const searchedObjectFeature: { test: string } = { test: 'test' };
+            service.setup({
+                ...blankConfig,
+                features: {
+                    searchedObjectFeature
+                }
+            });
+
+            const requestedFeatue = service.getFeature<{ test: string }>('searchedObjectFeature');
+            expect(requestedFeatue).toEqual(searchedObjectFeature);
+        });
+
+        it('should return default value if feature is not found', async () => {
+            const defaultValue = {};
+            service.setup(blankConfig);
+
+            const requestedFeatue = service.getFeature<{ test: string }>('searchedFeature', defaultValue);
+            expect(requestedFeatue).toEqual(defaultValue);
+        });
+    });
+
     it('should raise warning if setting up with missing config', () => {
         spyOn(console, 'warn').and.stub();
 

lib/extensions/src/lib/services/extension.service.ts

@@ -117,12 +117,13 @@ export class ExtensionService {
     /**
      * Gets features by key.
      *
-     * @param key Key string, using dot notation
-     * @returns Features array found by key
+     * @param key Key string using dot notation or array of strings
+     * @param defaultValue Default value returned if feature is not found, default is empty array
+     * @returns Feature found by key
      */
-    getFeature(key: string): any[] {
-        const properties: string[] = Array.isArray(key) ? [key] : key.split('.');
-        return properties.reduce((prev, curr) => prev && prev[curr], this.features) || [];
+    getFeature<T = any[]>(key: string | string[], defaultValue: any = []): T {
+        const properties: string[] = Array.isArray(key) ? key : key.split('.');
+        return properties.reduce((prev, curr) => prev && prev[curr], this.features) || defaultValue;
     }
 
     getElements<T extends ExtensionElement>(key: string, fallback: Array<T> = []): Array<T> {