Wednesday, March 22, 2006
Unit Tests should test Units... so.. abandon private or what?
In Evil Unit Tests, Paul Wheaton says that you should be picking on little independent units - it's supposed to be "unit" testing isnt' it! Tests that involve lots of pieces of the puzzle are really 'functional' tests - JUnit or no JUnit.
He says that functional tests aren't really as useful - they have fingers in too many pies - they tend to break as a result of changes some distance away.
I think I'm writing tests at the whole range of granularities, but it hadn't occurred to me that coarse ones might really be "functional" rather than "unit".
I think the not-being-able-to-test-private-methods thing might encourage (force?) people to write overly coarse grained ones too.
See the bit at thevery bottom - "I took out the keyword 'private',. In order to achieve testability, he's had to promote a method to package access. I have been doing that too, but feeling guilty about it..
He says that functional tests aren't really as useful - they have fingers in too many pies - they tend to break as a result of changes some distance away.
I think I'm writing tests at the whole range of granularities, but it hadn't occurred to me that coarse ones might really be "functional" rather than "unit".
I think the not-being-able-to-test-private-methods thing might encourage (force?) people to write overly coarse grained ones too.
See the bit at thevery bottom - "I took out the keyword 'private',. In order to achieve testability, he's had to promote a method to package access. I have been doing that too, but feeling guilty about it..
Comments:
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RC: Bear in mind I am either a HTML/CSS person or a PHP person... probably not the best person to ask about testing /anything/ apart from "hit refresh, does it look better, yes, woohoo" or "hit refresh, does it look better, no, shit"
# posted by 
: 10:09 AM
: 10:09 AM
KP: hehehe I know *exactly* where you're coming from as in a different job I did front end work. (In fact, I am from the era of evil netscape 4.7...)
But, I've heard there is a way to unit-ish test html webapp stuff. It's a module that lets you make a request, then reads the document it gets back into some sort of DOMish thing, and lets you set up tests which ask questions like "is there a form called foo on the page" "how many pixels to the left is it"... etc Dave, what's the name of that thing you use?
But, I've heard there is a way to unit-ish test html webapp stuff. It's a module that lets you make a request, then reads the document it gets back into some sort of DOMish thing, and lets you set up tests which ask questions like "is there a form called foo on the page" "how many pixels to the left is it"... etc Dave, what's the name of that thing you use?
DS: Well, we use the Perl module WWW::Mechanize (http://search.cpan.org/~petdance/WWW-Mechanize-1.18/lib/WWW/Mechanize.pm)
to make real requests to the front end, including completing forms, clicking on buttons etc. and testing that the returned page contains the right content.
You can do fairly easily write a test which does a search on google for 'ingenta' and checks that ingenta is returned on the first page:
#!/usr/bin/perl
use strict;
use warnings;
use WWW::Mechanize;
use Test::More tests => 2;
my $mech = WWW::Mechanize->new();
my $url = "http://www.google.co.uk";
$mech->get( $url );
# test we got the google search page
like( $mech->content, qr/pages from the UK/, "Successfully requested Google UK" );
# do a search
$mech->submit_form(
form_number => 1,
fields => {
q => "ingenta",
}
);
# check ingenta was returned
like( $mech->content, qr/On-line articles from 4500 journals/, "Google returned ingenta" );
Which gives:
perl mech.pl
1..2
ok 1 - Successfully requested Google UK
ok 2 - Google returned ingenta
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to make real requests to the front end, including completing forms, clicking on buttons etc. and testing that the returned page contains the right content.
You can do fairly easily write a test which does a search on google for 'ingenta' and checks that ingenta is returned on the first page:
#!/usr/bin/perl
use strict;
use warnings;
use WWW::Mechanize;
use Test::More tests => 2;
my $mech = WWW::Mechanize->new();
my $url = "http://www.google.co.uk";
$mech->get( $url );
# test we got the google search page
like( $mech->content, qr/pages from the UK/, "Successfully requested Google UK" );
# do a search
$mech->submit_form(
form_number => 1,
fields => {
q => "ingenta",
}
);
# check ingenta was returned
like( $mech->content, qr/On-line articles from 4500 journals/, "Google returned ingenta" );
Which gives:
perl mech.pl
1..2
ok 1 - Successfully requested Google UK
ok 2 - Google returned ingenta
# posted by : 10:10 AM
: 10:10 AM << Home
