[Test] Add test for class directive with spread attributes

test/runtime/samples/class-with-dynamic-attribute-and-spread/_config.js

@@ -0,0 +1,22 @@
+export default {
+	data: {
+		myClass: 'one two',
+		attributes: {
+			role: 'button'
+		}
+	},
+	html: `<div class="one two three" role="button"></div>`,
+
+	test ( assert, component, target, window ) {
+		component.set({
+			attributes: {
+				'aria-label': 'Test'
+			},
+			myClass: 'one'
+		});
+
+		assert.htmlEqual( target.innerHTML, `
+			<div class="one three" aria-label="Test"></div>
+		` );
+	}
+};

test/runtime/samples/class-with-dynamic-attribute-and-spread/main.html

@@ -0,0 +1 @@
+<div class="{ myClass }" class:three="true" {...attributes}></div>