[Tests] add implementation tests

test/tests.js

@@ -1,6 +1,36 @@
 'use strict';
 
-// eslint-disable-next-line no-unused-vars
+var hasSymbols = require('has-symbols')();
+
 module.exports = function runTests(hasOwn, t) {
-	// TODO
+	var badPropertyKey = { toString: function () { throw new SyntaxError('nope'); } };
+
+	t['throws'](
+		function () { hasOwn(null, badPropertyKey); },
+		TypeError,
+		'checks ToObject first'
+	);
+
+	t['throws'](
+		function () { hasOwn({}, badPropertyKey); },
+		SyntaxError,
+		'checks ToPropertyKey next'
+	);
+
+	var obj = { a: 1 };
+	t.equal('toString' in obj, true, 'object literal has non-own toString');
+	t.equal(hasOwn(obj, 'toString'), false, 'toString is not an own property');
+	t.equal(hasOwn(obj, 'a'), true, 'own property is recognized');
+
+	t.equal(hasOwn([], 'length'), true, 'non-enumerable own property is recognized');
+
+	t.test('Symbols', { skip: !hasSymbols }, function (st) {
+		var o = {};
+		o[Symbol.iterator] = true;
+		st.equal(hasOwn(o, Symbol.iterator), true, 'own symbol is recognized');
+
+		st.equal(hasOwn(Array.prototype, Symbol.iterator), true, 'built-in own symbol is recognized');
+
+		st.end();
+	});
 };