test(@angular-devkit/build-ng-packagr): custom tsconfig

Use the new tsConfig option in order to set a custom tsconfig file for the 'work' test
this example show how to change the ES level in lib and target
all the other options are required for now if we don't want to break the build
their should be removed once / if ng-packagr/ng-packagr#786 is released

Author: nlm-pro

tests/@angular_devkit/build_ng_packagr/ng-packaged/angular.json

@@ -9,7 +9,8 @@
         "build": {
           "builder": "../../../../packages/angular_devkit/build_ng_packagr:build",
           "options": {
-            "project": "projects/lib/ng-package.json"
+            "project": "projects/lib/ng-package.json",
+            "tsConfig": "projects/lib/tsconfig.lib.json"
           }
         },
         "test": {

tests/@angular_devkit/build_ng_packagr/ng-packaged/projects/lib/src/lib/lib.service.ts

@@ -5,4 +5,8 @@ export class LibService {
 
   constructor() { }
 
+  testEs2016() {
+    return ['foo', 'bar'].includes('foo');
+  }
+
 }

tests/@angular_devkit/build_ng_packagr/ng-packaged/projects/lib/tsconfig.lib.json

@@ -0,0 +1,12 @@
+{
+  "compilerOptions": {
+    "target": "es6",
+    "moduleResolution": "node",
+    "sourceMap": true,
+    "inlineSources": true,
+    "emitDecoratorMetadata": true,
+    "experimentalDecorators": true,
+    "importHelpers": true,
+    "lib": ["dom", "es2016"]
+  }
+}