How to get HTML5 validation message with selenium?

Question

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 g

Answer 1

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);

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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");