How to get HTML5 validation message with selenium?

问题

Please see this website.

After click log in i have this User credentials form and after try to login with missing Email Address or Password i got this message:

So i try to find this element by print all the page HTML (driver.getPageSource()) but this text is missing.

Any idea how to verify that i have this error message ?

回答1:

The validation messages are not the part of your DOM. They are generated because your input fileds have required attribute. If you see the HTML of your fields -

<input type="text" placeholder="Enter Username" name="uname" required="">

You can see it has required attribute turned on. Check this out. You can verify that your fields have this required attribute or not, like this-

WebElement inputElement = driver.findElement(By.name("uname"));
JavascriptExecutor js = (JavascriptExecutor) driver;  
boolean isRequired = (Boolean) js.executeScript("return arguments[0].required;",inputElement)
if(isRequired )
{
   //element is required and validation error will popup if the field is empty.
}

There is no need to care about whether the message appears or not because that will handled by the browser.

回答2:

Attribute validationMessage will return the message, that will be showing if validation fails:

WebElement username = driver.findElement(By.name("uname"));    
String validationMessage = username.getAttribute("validationMessage");

If element has required attribute, browser will show the message after submitting the form:

boolean required = Boolean.parseBoolean(username.getAttribute("required"));

You can check whether entered value is valid:

boolean valid = (Boolean)((JavascriptExecutor)driver).executeScript("return arguments[0].validity.valid;", username);

---

Not: message text and validation is customizable. If you want to test customized validation and message.

Here test code for custom validation(Java, TestNG):

Assert.assertTrue(Boolean.parseBoolean(username.getAttribute("required")), "Username is required and message should be showin");
Assert.assertEquals(username.getAttribute("validationMessage"), "My custom message", "Message text control");

username.sendKeys("@vasya ");
Assert.assertTrue((Boolean)((JavascriptExecutor)driver).executeScript("return arguments[0].validity.valid;", username), "Username has special characters");

来源：https://stackoverflow.com/questions/52029267/how-to-get-html5-validation-message-with-selenium