set attribute values for snapshotting input values

addon/snapshot.js

@@ -16,6 +16,18 @@ function getDoctype() {
   return doctype;
 }
 
+// Set the property value into the attribute value for snapshotting inputs
+function setAttributeValues(dom) {
+  let inputs = dom.find('input');
+
+  for (let i = 0; i < inputs.length; i++) {
+    let input = inputs[i];
+    input.setAttribute('value', input.value);
+  }
+
+  return dom;
+}
+
 export function percySnapshot(name, options) {
   // Skip if Testem is not available (we're probably running from `ember server` and Percy is not
   // enabled anyway).
@@ -41,11 +53,13 @@ export function percySnapshot(name, options) {
   let testingContainer = domCopy.find('#ember-testing-container');
 
   if (scope) {
-    snapshotHtml = Ember.$('#ember-testing-container').find(scope).html();
+    snapshotHtml = Ember.$('#ember-testing-container').find(scope);
   } else {
-    snapshotHtml = testingContainer.html();
+    snapshotHtml = testingContainer;
   }
 
+  snapshotHtml = setAttributeValues(snapshotHtml).html();
+
   // Hoist the testing container contents up to the body.
   // We need to use the original DOM to keep the head stylesheet around.
   domCopy.find('body').html(snapshotHtml);

tests/integration/components/dummy-box-test.js

@@ -37,3 +37,12 @@ test('name is autogenerated if given a Mocha test object', function(assert) {
   };
   percySnapshot(mochaTestDouble);
 });
+
+test('it snapshots input values', function(assert) {
+  this.render(hbs`{{input value="Testing"}}`);
+
+  assert.equal(this.$('input')[0].value, 'Testing', 'value property is set');
+  assert.equal(this.$('input').attr('value'), undefined, 'value attribute is not set');
+
+  percySnapshot('input with value');
+});