Move throws assertion to unit test

emberjs/ember-qunit#256 (comment)

tests/unit/components/freestyle-dynamic/component-test.js

@@ -0,0 +1,13 @@
+import { moduleForComponent, test } from 'ember-qunit';
+
+moduleForComponent('freestyle-dynamic', 'Unit | Component | freestyle dynamic', {
+  unit: true
+});
+
+test('an assertion is thrown if dynamicProperties is undefined', function(assert) {
+  assert.expect(1);
+
+  assert.throws(() => {
+    this.subject({ dynamicProperties: undefined });
+  }, /Assertion Failed: dynamicProperties passed into freestyle-dynamic must be an object. {2}You passed: undefined/)
+});