The document discusses a technique called the 'selenium sandwich' for validating browser content by feeding the browser from a controlled server. It emphasizes the importance of using predetermined responses to facilitate the testing process, overcoming challenges associated with live server interaction. Future discussions will focus on fully implementing this technique and addressing the need for a proxy server.

1. Selenium Sandwich Part 2: Add some meat
Steven Lembark
Workhorse Computing
lembark@wrkhors.com

2. What is a Selenium Sandwich?
Tasty!!!
No really..

3. What is a Selenium Sandwich?
Last time we saw how to wrap an existing object.
Add some high-level functions to it.
Now we get to use them.

4. Chicken & Egg
How do you validate what's in the browser?
Without knowing the request and the reponse?

5. Chicken & Egg
How do you validate what's in the browser?
Without knowing the request and the reponse?
A: You can't.
That's why debugging front ends is so hard:
All you see is what's in the browser.

6. Fix: Feed the browser from a server you control.
Sounds easy enough:
Make a request you know.
To a server you control.
Get back a known response.
Validate what is in the browser.

7. Fix: Feed the browser from a server you control.
Sounds easy enough:
Make a request you know.
To a server you control.
Get back a known response.
Validate what is in the browser.
Q: How do you control the response?

8. The dynamic fly in our soup
You usually can't control the response.
Most browser-code testing uses an active server.
Bugs in the server show up in your browser.
Validating the browser requires a fixed response.

9. The dynamic fly in our soup
You usually can't control the response.
Most browser-code testing uses an active server.
Bugs in the server show up in your browser.
Validating the browser requires a fixed response.
That means you can't use the “real” server.

10. What's a fake server?
A: One that hands back a canned response.
Result:
Use the browser to request the pre-determined reply.
Validate the browser contents using selenium.

11. Defining content
PSGI makes defining the response easy.
PSGI reply format:
[
http code,
[ http headers ],
[ http returned content ]
]
[ 200, [], [ “Hello, world!<p>” ]

12. PSGI is easy in YAML
---
-
- 200
- []
- Hello, worldn

13. A complete setup & request
---
-
# high-level call to find and click “submit”
- find_click
- submit
-
# hardwired response
- 200
- []
- [ “hello, world!<p>”, “in flowed text<p>” ]

14. Plack is your friend.
Don't tell your dentist I said so...
POST some YAML to a server and it can do the deed.
<http://www.slideshare.net/lembark/get-your-teeth-into-
plack?qid=9164c31a-2e24-4ac3-ae97-
5fdfff95ec84&v=default&b=&from_search=1>

15. Er... how? You still need a browser...
Easy: Plack is Perl, remember?
PUT SELENIUM CODE
INTO THE BROWSER!!!

16. Server on one port gets a request
my $response = '';
my $validate = '';
sub setup_test # handler for port 5001
{
my $env = shift;
my $control = Load $env->{ POST_DATA };
( $response, $validate ) = @$contrl{qw( response validate )};
my $browser = Selenium::Handler->new;
run_browser_commands $control;
}
sub run_test # handler for port 80
{
my $env = shift; # from setup_test.
validate_request $env, $validate; # sanity checks.
$response # canned response.
}

17. What just happened?
HTTP server sent itself a request.
From a browser.
Using selenium.

18. What just happened?
HTTP server sent itself a request.
From a browser.
Using selenium.
It is a closed loop.
You can test it.

19. Next Month: Actually making it work.
Main issue is getting requests back to the server.
Which requires a proxy server.
And a bit of black magic under the hood.