chore: add Jest + Examples & helpers (#74)

* Jest testing instead of Karma & Jasmine

* refactor: use optional chaining

Co-authored-by: Wassim Chegham <[email protected]>

Co-authored-by: Fayçal Tirich <[email protected]>
Co-authored-by: Wassim Chegham <[email protected]>

Author: fayway

angular.json

@@ -79,21 +79,10 @@
           }
         },
         "test": {
-          "builder": "@angular-devkit/build-angular:karma",
+          "builder": "@angular-builders/jest:run",
           "options": {
-            "main": "src/test.ts",
-            "polyfills": "src/polyfills.ts",
-            "tsConfig": "tsconfig.spec.json",
-            "karmaConfig": "karma.conf.js",
-            "assets": [
-              "src/favicon.ico",
-              "src/assets"
-            ],
-            "styles": [
-              "./node_modules/@angular/material/prebuilt-themes/indigo-pink.css",
-              "src/styles.css"
-            ],
-            "scripts": []
+            "jestConfig": "jest.config.js",
+            "setupFilesAfterEnv": "<rootDir>/test-setup.ts"
           }
         },
         "lint": {
@@ -142,11 +131,10 @@
           }
         },
         "test": {
-          "builder": "@angular-devkit/build-angular:karma",
+          "builder": "@angular-builders/jest:run",
           "options": {
-            "main": "projects/manekinekko/angular-web-bluetooth/src/test.ts",
-            "tsConfig": "projects/manekinekko/angular-web-bluetooth/tsconfig.spec.json",
-            "karmaConfig": "projects/manekinekko/angular-web-bluetooth/karma.conf.js"
+            "jestConfig": "projects/manekinekko/angular-web-bluetooth/jest.config.js",
+            "setupFilesAfterEnv": "./test-setup.ts"
           }
         },
         "lint": {