[🐛 Bug]: Cookies management is not consistent

[nvborisenko]

What happened?

In C#:

driver.FindElement(By.CssSelector("abc")); // throws NoSuchElement

driver.Manage().Cookies.GetCookieNamed("abc"); // null if not found

But according spec it should throw an exception: https://www.w3.org/TR/webdriver2/#get-named-cookie

How can we reproduce the issue?

It is about API consistency

Relevant log output

No output

Operating System

any

Selenium version

any

What are the browser(s) and version(s) where you see this issue?

any

What are the browser driver(s) and version(s) where you see this issue?

any

Are you using Selenium Grid?

No response

[github-actions]

@nvborisenko, thank you for creating this issue. We will troubleshoot it as soon as we can.

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Thank you!

[nvborisenko]

From C# perspective it would be nice to:

• leave it as is (and mark it as deprecated)
• new method GetCookie(string name) which throws if not found
• new method bool TryGetCookie(string name, out Cookie cookie) which is known pattern

[p0deje]

I would consider this to be a common API change that needs to follow the deprecation process:

1. Deprecate the current method if it returns null with a message that it will start throwing an error in the upcoming releases.
2. Wait for 2-3 releases.
3. Replace implementation.

I don't think Try* is necessary, but I've never used Selenium directly and always used a wrapper (Watir, Capybara). These libraries can easily handle the exception internally.

[nvborisenko]

Current API is bad, it hides real reason under hood. Let's compare... I want to:

• Delete file by its path
• Get an element from dictionary by key
• Connect to remote network point by address
• Remove an element from an array by index = 100, where the array has only 50 elements

In all cases it throws/raises exception (in all programming languages?), like "Dear user, you are doing something wrong". Selenium should not be silent. #14545 shows why. When user deletes cookie via .DeleteCookieNamed("abc") and this method returns null: does it mean the cookie is deleted successfully or the cookie doesn't exists - no clues. It should be predictable.

[RenderMichael]

Taking a look at how users actually use this method in the wild: https://grep.app/search?q=GetCookieNamed%28

It looks like more often than not, people are just making an assertion that a cookie does not exist. In other words, following the WebDriver spec would require making users catch an exception (or more specifically, assert that an exception is thrown).

If we don’t want a Try*, method, can we at least have a ContainsCookieNamed method? that would bridge the gap for (what seems to me as) the majority use case.