Add some tests for Et2Box.disabled to make sure it behaves.

api/js/etemplate/Et2Box/test/Et2Box.test.ts

@@ -1,7 +1,7 @@
 /**
  * Test file for Etemplate webComponent base widget Et2Box
  */
-import {assert, fixture} from '@open-wc/testing';
+import {assert, elementUpdated, fixture} from '@open-wc/testing';
 import {Et2Box} from "../Et2Box";
 import {html} from "lit-element";
 
@@ -28,5 +28,40 @@ describe("Box widget", () =>
 	{
 		element.set_label("Nope");
 		assert.isEmpty(element.shadowRoot.querySelectorAll('.et2_label'));
-	})
+	});
+
+	it('disabled', async() =>
+	{
+		element.disabled = true;
+
+		// wait for asychronous changes to the DOM
+		// @ts-ignore TypeScript is not recognizing that this widget is a LitElement
+		await elementUpdated(element);
+
+		let style = window.getComputedStyle(<Element><unknown>element);
+		assert.include(element.getAttributeNames(), "disabled", "Missing disabled attribute");
+		assert.equal(style.display, "none", "Did not hide when disabled");
+
+		element.disabled = false;
+		// wait for asychronous changes to the DOM
+		// @ts-ignore TypeScript is not recognizing that this widget is a LitElement
+		await elementUpdated(element);
+
+		// Check attribute goes
+		assert.notInclude(element.getAttributeNames(), "disabled", "Still had disabled attribute after setting it to false");
+		style = window.getComputedStyle(<Element><unknown>element);
+		assert.notEqual(style.display, "none", "Did not show when not disabled");
+
+		/** Check via set method instead of property **/
+		element.set_disabled(true);
+
+		// wait for asychronous changes to the DOM
+		// @ts-ignore TypeScript is not recognizing that this widget is a LitElement
+		await elementUpdated(element);
+		style = window.getComputedStyle(<Element><unknown>element);
+		assert.include(element.getAttributeNames(), "disabled", "Missing disabled attribute");
+		assert.equal(style.display, "none", "Did not hide when disabled via set_disabled()");
+
+	});
+
 });