WebDriver tricks #1
Finally decided to start series (i hope) of blog posts describing tricks that could help developers to write more robust Selenium / WebDriver tests. Here are two of them. This information is all covered by Selenium JavaDocs. But if you’re good programmer - will you ever read JavaDocs ? :)
Trick
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Q: How to find element by XPath expression under certain node of HTML tree and not from HTML tree root ?
-
A: You should prefix your XPath expression with
.//(dot in the beginning)
Having HTML
<html>
<body>
<div id="panel1">
<div>
<span class="myClass">ITEM1</span>
</div>
</div>
<div id="panel2">
<div>
<span class="myClass">ITEM2</span>
</div>
</div>
</body>
</html>Java test below illustrates the difference
WebElement panel2 = webDriver.findElement(By.id("panel2"));
WebElement el1 = panel2.findElement(By.xpath("//span[@class = 'myClass']"));
WebElement el2 = panel2.findElement(By.xpath(".//span[@class = 'myClass']"));
assert el1.getText().equals("ITEM1");
assert el2.getText().equals("ITEM2");XPath expression //span[@class = 'myClass'] makes WebDriver to look for element using HTML root as starting point
even if we call findElement() not at webDriver variable.
From other hand using XPath starting from dot, i.e. .//span[@class = 'myClass']
instructs WebDriver to use panel2 as starting point.
Trick
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Q: How to check that certain element doesn’t exist in HTML tree.
-
A: There’s common anti-pattern frequently used by developers.
WebElement notExist = null;
try {
notExist = webDriver.findElement(By.xpath("//div[@id='iAmNotHere']"));
} catch (NoSuchElementException e) {
}
assert notExist == null;This approach has enough disadvantages and best practices violations. We ain’t gonna cover them here ;) Instead we can use much simpler code to achieve the same result.
assert webDriver.findElements(By.xpath("//div[@id='iAmNotHere']")).size() == 0;