tests: Add tests for duck typing

tests/duck_typing.test.js

@@ -0,0 +1,85 @@
+import {test} from 'node:test';
+import assert from 'node:assert';
+import './document.js';
+
+import {mount, OArray, Observer} from '../index.js';
+
+const createCustomNode = () => {
+	let elems = [];
+	let obj = {
+		elems,
+		insertBefore: (elem, before) => {
+			const i = elems.indexOf(before);
+			if (i === -1) {
+				elems.push(elem);
+			} else {
+				elems.splice(i, 0, elem);
+			}
+		},
+		replaceChild: (newNode, oldNode) => {
+			const i = elems.indexOf(oldNode);
+			elems.splice(i, 1, newNode);
+		},
+		removeChild: (node) => {
+			const i = elems.indexOf(node);
+			elems.splice(i, 1);
+		},
+		set textContent (content) {
+			elems.splice(0, elems.length);
+			obj.fastClear = true;
+		},
+		get firstChild () {
+			return elems[0];
+		},
+	};
+
+	return obj;
+};
+
+test("duck type basic", () => {
+	const elem = createCustomNode();
+
+	mount(elem, "hello world");
+	assert.deepEqual(elem.elems.map(e => e.tree()), ["hello world"]);
+});
+
+test("duck type basic remove", () => {
+	const elem = createCustomNode();
+
+	const remove = mount(elem, "hello world");
+	remove();
+
+	assert.deepEqual(elem.elems.map(e => e.tree()), []);
+});
+
+test("duck type replace", () => {
+	const elem = createCustomNode();
+
+	const obs = Observer.mutable("hello world");
+	mount(elem, obs);
+	obs.set("new");
+
+	assert.deepEqual(elem.elems.map(e => e.tree()), ["new"]);
+});
+
+test("duck type array clear", () => {
+	const elem = createCustomNode();
+
+	const obs = OArray([1, 2, 3]);
+	mount(elem, obs);
+	obs.splice(0, obs.length);
+
+	assert.deepEqual(elem.elems.map(e => e.tree()), []);
+	assert(elem.fastClear === true)
+});
+
+test("duck type array nested clear", () => {
+	const elem = createCustomNode();
+
+	const obs = OArray([1, 2, 3]);
+	mount(elem, OArray([obs]));
+	obs.splice(0, obs.length);
+
+	assert.deepEqual(elem.elems.map(e => e.tree()), []);
+	assert(elem.fastClear === true)
+});

tests/transform.test.js

@@ -131,6 +131,7 @@ for (const file of files) {
 		'array.reconciliation.test.js',
 		'replacement.test.js',
 		'static.test.js',
+		'duck_typing.test.js',
 	].includes(file)) {
 		describe("iife " + file, transform(file, {
 			assure_import: /^$/,