added function-builder test

Signed-off-by: Antonio Mendoza Pérez <antmendoza@gmail.com>

Author: antmendoza

tests/lib/builders/function-builder.spec.ts

@@ -17,9 +17,16 @@
 import { functionBuilder } from '../../../src/lib/builders/function-builder';
 
 describe('function ', () => {
-  it('should build an object without default type', () => {
+  it('should build an object without default type if not set', () => {
     const fn = functionBuilder().name('function').operation('operation').build();
 
     expect(fn.type).toBeUndefined();
   });
+
+  it('should build an object with type= set value ', () => {
+    expect(functionBuilder().name('function').operation('operation').type('expression').build().type).toBe(
+      'expression'
+    );
+    expect(functionBuilder().name('function').operation('operation').type('rest').build().type).toBe('rest');
+  });
 });