Added toVNode domApi test

test/core.js

@@ -10,6 +10,7 @@ var patch = snabbdom.init([
 var h = require('../h').default;
 var toVNode = require('../tovnode').default;
 var vnode = require('../vnode').default;
+var htmlDomApi = require('../htmldomapi').htmlDomApi;
 
 function prop(name) {
   return function(obj) {
@@ -336,7 +337,28 @@ describe('snabbdom', function() {
         assert.strictEqual(elm.childNodes.length, 1);
         assert.strictEqual(elm.childNodes[0].nodeType, 1);
         assert.strictEqual(elm.childNodes[0].textContent, 'Hello');
-      })
+      });
+      it('can work with domApi', function () {
+        var domApi = Object.assign({}, htmlDomApi, {
+            tagName: function(elm) { return 'x-' + elm.tagName.toUpperCase(); }
+        });
+        var h2 = document.createElement('h2');
+        h2.id = 'hx';
+        h2.setAttribute('data-env', "xyz");
+        var text = document.createTextNode("Foobar");
+        var elm = document.createElement('div');
+        elm.id = 'id';
+        elm.className = 'class other';
+        elm.setAttribute('data', 'value');
+        elm.appendChild(h2);
+        elm.appendChild(text);
+        var vnode = toVNode(elm, domApi);
+        assert.equal(vnode.sel, 'x-div#id.class.other');
+        assert.deepEqual(vnode.data, {attrs: {'data': 'value'}});
+        assert.equal(vnode.children[0].sel, 'x-h2#hx');
+        assert.deepEqual(vnode.children[0].data, {attrs: {'data-env': 'xyz'}});
+        assert.equal(vnode.children[1].text, 'Foobar');
+      });
     });
     describe('updating children with keys', function() {
       function spanNum(n) {