更新

test/e2e/custom-assertions/elementCount.js

@@ -0,0 +1,27 @@
+// A custom Nightwatch assertion.
+// The assertion name is the filename.
+// Example usage:
+//
+//   browser.assert.elementCount(selector, count)
+//
+// For more information on custom assertions see:
+// http://nightwatchjs.org/guide#writing-custom-assertions
+
+exports.assertion = function (selector, count) {
+  this.message = 'Testing if element <' + selector + '> has count: ' + count
+  this.expected = count
+  this.pass = function (val) {
+    return val === this.expected
+  }
+  this.value = function (res) {
+    return res.value
+  }
+  this.command = function (cb) {
+    var self = this
+    return this.api.execute(function (selectorToCount) {
+      return document.querySelectorAll(selectorToCount).length
+    }, [selector], function (res) {
+      cb.call(self, res)
+    })
+  }
+}