Add tests for #1870

render/tests/test-attributes.js

@@ -288,6 +288,43 @@ o.spec("attributes", function() {
 
 			// o(b.dom.value).equals("")
 		})
+		o("isn't set when equivalent to the previous value and focused", function() {
+			var $window = domMock({spy: o.spy})
+			var root = $window.document.body
+			var render = vdom($window).render
+
+			var a = {tag: "textarea"}
+			var b = {tag: "textarea", attrs: {value: "1"}}
+			var c = {tag: "textarea", attrs: {value: "1"}}
+			var d = {tag: "textarea", attrs: {value: 1}}
+			var e = {tag: "textarea", attrs: {value: 2}}
+
+			render(root, [a])
+			var spies = $window.__getSpies(a.dom)
+			a.dom.focus()
+
+			o(spies.valueSetter.callCount).equals(0)
+
+			render(root, [b])
+
+			o(b.dom.value).equals("1")
+			o(spies.valueSetter.callCount).equals(1)
+
+			render(root, [c])
+
+			o(c.dom.value).equals("1")
+			o(spies.valueSetter.callCount).equals(1)
+
+			render(root, [d])
+
+			o(d.dom.value).equals("1")
+			o(spies.valueSetter.callCount).equals(1)
+
+			render(root, [e])
+
+			o(d.dom.value).equals("2")
+			o(spies.valueSetter.callCount).equals(2)
+		})
 	})
 	o.spec("link href", function() {
 		o("when link href is true, attribute is present", function() {

test-utils/domMock.js

@@ -345,18 +345,22 @@ module.exports = function(options) {
 				if (element.nodeName === "TEXTAREA") {
 					var wasNeverSet = true
 					var value = ""
-					Object.defineProperty(element, "value", {
+					var valueSetter = spy(function(v) {
-						get: function() {
-							return wasNeverSet && this.firstChild ? this.firstChild.nodeValue : value
-						},
-						set: function(v) {
 						wasNeverSet = false
 						/*eslint-disable no-implicit-coercion*/
 						value = v === null ? "" : "" + v
 						/*eslint-enable no-implicit-coercion*/
+					})
+					Object.defineProperty(element, "value", {
+						get: function() {
+							return wasNeverSet && this.firstChild ? this.firstChild.nodeValue : value
 						},
+						set: valueSetter,
 						enumerable: true,
 					})
+					registerSpies(element, {
+						valueSetter: valueSetter
+					})
 				}
 
 				/* eslint-disable radix */

test-utils/tests/test-domMock.js

@@ -1237,5 +1237,21 @@ o.spec("domMock", function() {
 			o(spies.valueSetter.this).equals(option)
 			o(spies.valueSetter.args[0]).equals("aaa")
 		})
+		o("textarea elements have spies on value setters", function() {
+			var textarea = $window.document.createElement("textarea")
+
+			var spies = $window.__getSpies(textarea)
+
+			o(typeof spies).equals("object")
+			o(spies).notEquals(null)
+			o(typeof spies.valueSetter).equals("function")
+			o(spies.valueSetter.callCount).equals(0)
+
+			textarea.value = "aaa"
+
+			o(spies.valueSetter.callCount).equals(1)
+			o(spies.valueSetter.this).equals(textarea)
+			o(spies.valueSetter.args[0]).equals("aaa")
+		})
 	})
 })