Inline attributes semantics and tests

cypress/fixtures/Entity1.js

@@ -0,0 +1,19 @@
+import IEntity from "../../js/entity/IEntity.js"
+
+export default class Entity1 extends IEntity {
+
+    static attributes = {
+        a: {
+            type: Number,
+        },
+        b: {
+            type: Number,
+        },
+    }
+
+    constructor(values = {}) {
+        values.a ??= 8
+        values.b ??= 9
+        super(values)
+    }
+}