| Test::Base(3) | User Contributed Perl Documentation | Test::Base(3) |
Test::Base - A Data Driven Testing Framework
A new test module:
# lib/MyProject/Test.pm
package MyProject::Test;
use Test::Base -Base;
use MyProject;
package MyProject::Test::Filter;
use Test::Base::Filter -base;
sub my_filter {
return MyProject->do_something(shift);
}
A sample test:
# t/sample.t
use MyProject::Test;
plan tests => 1 * blocks;
run_is input => 'expected';
sub local_filter {
s/my/your/;
}
__END__
=== Test one (the name of the test)
--- input my_filter local_filter
my
input
lines
--- expected
expected
output
=== Test two
This is an optional description
of this particular test.
--- input my_filter
other
input
lines
--- expected
other expected
output
Testing is usually the ugly part of Perl module authoring. Perl gives you a standard way to run tests with Test::Harness, and basic testing primitives with Test::More. After that you are pretty much on your own to develop a testing framework and philosophy. Test::More encourages you to make your own framework by subclassing Test::Builder, but that is not trivial.
Test::Base gives you a way to write your own test framework base class that is trivial. In fact it is as simple as two lines:
package MyTestFramework;
use Test::Base -Base;
A module called "MyTestFramework.pm" containing those two lines, will give all the power of Test::More and all the power of Test::Base to every test file that uses it. As you build up the capabilities of "MyTestFramework", your tests will have all of that power as well.
"MyTestFramework" becomes a place for you to put all of your reusable testing bits. As you write tests, you will see patterns and duplication, and you can "upstream" them into "MyTestFramework". Of course, you don't have to subclass Test::Base at all. You can use it directly in many applications, including everywhere you would use Test::More.
Test::Base concentrates on offering reusable data driven patterns, so that you can write tests with a minimum of code. At the heart of all testing you have inputs, processes and expected outputs. Test::Base provides some clean ways for you to express your input and expected output data, so you can spend your
time focusing on that rather than your code scaffolding.
Test::Base extends Test::More and exports all of its functions. So you can basically write your tests the same as Test::More. Test::Base also exports many functions of its own:
Diff output requires the optional "Text::Diff" CPAN module. If you don't have this module, the "is()" function will simply give you normal Test::More output. To disable diffing altogether, set the "TEST_SHOW_NO_DIFFS" environment variable (or $ENV{TEST_SHOW_NO_DIFFS}) to a true value. You can also call the "no_diff" function as a shortcut.
Each Test::Base::Block object has methods that correspond to the names of that object's data sections. There is also a "name" and a "description" method for accessing those parts of the block if they were specified.
The "blocks" function can take an optional single argument, that indicates to only return the blocks that contain a particular named data section. Otherwise "blocks" returns all blocks.
my @all_of_my_blocks = blocks;
my @just_the_foo_blocks = blocks('foo');
while (my $block = next_block) {
...
}
It returns undef after all blocks have been iterated over. It can then be called again to reiterate.
The "run" function takes a subroutine as an argument, and calls the sub one time for each block in the specification. It passes the current block object to the subroutine.
run {
my $block = shift;
is(process($block->foo), $block->bar, $block->name);
};
run_is 'foo', 'bar';
If no data sections are given "run_is" will try to detect them automatically.
NOTE: Test::Base will silently ignore any blocks that don't
contain
both sections.
run_like 'foo', qr{<html.*};
run_like 'foo', 'match';
run_unlike 'foo', qr{<html.*};
run_unlike 'foo', 'no_match';
NOTE: If you do not specify either a plan, or run any tests,
the
"run_compare" function will
automatically be run.
You can also specify a hash ref that maps data section names to an array ref of filters for that data type.
filters {
xxx => [qw(chomp lines)],
yyy => ['yaml'],
zzz => 'eval',
};
If a filters list has only one element, the array ref is optional.
use Test::Base;
filters_delay;
plan tests => 1 * blocks;
for my $block (blocks) {
...
$block->run_filters;
ok($block->is_filtered);
...
}
In the code above, the filters are called manually, using the "run_filters" method of Test::Base::Block. In functions like "run_is", where the tests are run automatically, filtering is delayed until right before the test.
sub my_filter {
my $args = filter_arguments;
# is($args, 'whazzup');
...
}
__DATA__
=== A test
--- data my_filter=whazzup
my $out = '';
tie_output(*STDOUT, $out);
print "Hey!\n";
print "Che!\n";
untie *STDOUT;
is($out, "Hey!\nChe!\n");
Test::Base allows you to specify your test data in an external file, the DATA section of your program or from a scalar variable containing all the text input.
A test specification is a series of text lines. Each test (or block) is separated by a line containing the block delimiter and an optional test "name". Each block is further subdivided into named sections with a line containing the data delimiter and the data section name. A "description" of the test can go on lines after the block delimiter but before the first data section.
Here is the basic layout of a specification:
=== <block name 1>
<optional block description lines>
--- <data section name 1> <filter-1> <filter-2> <filter-n>
<test data lines>
--- <data section name 2> <filter-1> <filter-2> <filter-n>
<test data lines>
--- <data section name n> <filter-1> <filter-2> <filter-n>
<test data lines>
=== <block name 2>
<optional block description lines>
--- <data section name 1> <filter-1> <filter-2> <filter-n>
<test data lines>
--- <data section name 2> <filter-1> <filter-2> <filter-n>
<test data lines>
--- <data section name n> <filter-1> <filter-2> <filter-n>
<test data lines>
Here is a code example:
use Test::Base;
delimiters qw(### :::);
# test code here
__END__
### Test One
We want to see if foo and bar
are really the same...
::: foo
a foo line
another foo line
::: bar
a bar line
another bar line
### Test Two
::: foo
some foo line
some other foo line
::: bar
some bar line
some other bar line
::: baz
some baz line
some other baz line
This example specifies two blocks. They both have foo and bar data sections. The second block has a baz component. The block delimiter is "###" and the data delimiter is ":::".
The default block delimiter is "===" and the default data delimiter is "--- ".
There are some special data section names used for control purposes:
--- SKIP
--- ONLY
--- LAST
A block with a SKIP section causes that test to be ignored. This is useful to disable a test temporarily.
A block with an ONLY section causes only that block to be used. This is useful when you are concentrating on getting a single test to pass. If there is more than one block with ONLY, the first one will be chosen.
Because ONLY is very useful for debugging and sometimes you forgot to remove the ONLY flag before committing to the VCS or uploading to CPAN, Test::Base by default gives you a diag message saying I found ONLY ... maybe you're debugging?. If you don't like it, use "no_diag_on_only".
A block with a LAST section makes that block the last one in the specification. All following blocks will be ignored.
The real power in writing tests with Test::Base comes from its filtering capabilities. Test::Base comes with an ever growing set of useful generic filters than you can sequence and apply to various test blocks. That means you can specify the block serialization in the most readable format you can find, and let the filters translate it into what you really need for a test. It is easy to write your own filters as well.
Test::Base allows you to specify a list of filters to each data section of each block. The default filters are "norm" and "trim". These filters will be applied (in order) to the data after it has been parsed from the specification and before it is set into its Test::Base::Block object.
You can add to the default filter list with the "filters" function. You can specify additional filters to a specific block by listing them after the section name on a data section delimiter line.
Example:
use Test::Base;
filters qw(foo bar);
filters { perl => 'strict' };
sub upper { uc(shift) }
__END__
=== Test one
--- foo trim chomp upper
...
--- bar -norm
...
--- perl eval dumper
my @foo = map {
- $_;
} 1..10;
\ @foo;
Putting a "-" before a filter on a delimiter line, disables that filter.
Each filter can take either a scalar or a list as input, and will return either a scalar or a list. Since filters are chained together, it is important to learn which filters expect which kind of input and return which kind of output.
For example, consider the following filter list:
norm trim lines chomp array dumper eval
The data always starts out as a single scalar string. "norm" takes a scalar and returns a scalar. "trim" takes a list and returns a list, but a scalar is a valid list. "lines" takes a scalar and returns a list. "chomp" takes a list and returns a list. "array" takes a list and returns a scalar (an anonymous array reference containing the list elements). "dumper" takes a list and returns a scalar. "eval" takes a scalar and creates a list.
A list of exactly one element works fine as input to a filter requiring a scalar, but any other list will cause an exception. A scalar in list context is considered a list of one element.
Data accessor methods for blocks will return a list of values when used in list context, and the first element of the list in scalar context. This is usually "the right thing", but be aware.
Test::Base comes with large set of stock filters. They are in the "Test::Base::Filter" module. See Test::Base::Filter for a listing and description of these filters.
Creating filter extensions is very simple. You can either write a function in the "main" namespace, or a method in the "Test::Base::Filter" namespace or a subclass of it. In either case the text and any extra arguments are passed in and you return whatever you want the new value to be.
Here is a self explanatory example:
use Test::Base;
filters 'foo', 'bar=xyz';
sub foo {
transform(shift);
}
sub Test::Base::Filter::bar {
my $self = shift; # The Test::Base::Filter object
my $data = shift;
my $args = $self->current_arguments;
my $current_block_object = $self->block;
# transform $data in a barish manner
return $data;
}
If you use the method interface for a filter, you can access the block internals by calling the "block" method on the filter object.
Normally you'll probably just use the functional interface, although all the builtin filters are methods.
Note that filters defined in the "main" namespace can look like:
sub filter9 {
s/foo/bar/;
}
since Test::Base automatically munges the input string into $_ variable and checks the return value of the function to see if it looks like a number. If you must define a filter that returns just a single number, do it in a different namespace as a method. These filters don't allow the simplistic $_ munging.
Test::Base has a nice functional interface for simple usage. Under the hood everything is object oriented. A default Test::Base object is created and all the functions are really just method calls on it.
This means if you need to get fancy, you can use all the object oriented stuff too. Just create new Test::Base objects and use the functions as methods.
use Test::Base;
my $blocks1 = Test::Base->new;
my $blocks2 = Test::Base->new;
$blocks1->delimiters(qw(!!! @@@))->spec_file('test1.txt');
$blocks2->delimiters(qw(### $$$))->spec_string($test_data);
plan tests => $blocks1->blocks + $blocks2->blocks;
# ... etc
In Test::Base, blocks are exposed as Test::Base::Block objects. This section lists the methods that can be called on a Test::Base::Block object. Of course, each data section name is also available as a method.
One of the nicest things about Test::Base is that it is easy to subclass. This is very important, because in your personal project, you will likely want to extend Test::Base with your own filters and other reusable pieces of your test framework.
Here is an example of a subclass:
package MyTestStuff;
use Test::Base -Base;
our @EXPORT = qw(some_func);
sub some_func {
(my ($self), @_) = find_my_self(@_);
...
}
package MyTestStuff::Block;
use base 'Test::Base::Block';
sub desc {
$self->description(@_);
}
package MyTestStuff::Filter;
use base 'Test::Base::Filter';
sub upper {
$self->assert_scalar(@_);
uc(shift);
}
Note that you don't have to re-Export all the functions from Test::Base. That happens automatically, due to the powers of Spiffy.
The first line in "some_func" allows it to be called as either a function or a method in the test code.
You might be thinking that you do not want to use Test::Base in you modules, because it adds an installation dependency. Fear not. Module::Install::TestBase takes care of that.
Just write a Makefile.PL that looks something like this:
use inc::Module::Install;
name 'Foo';
all_from 'lib/Foo.pm';
use_test_base;
WriteAll;
The line with "use_test_base" will automatically bundle all the code the user needs to run Test::Base based tests.
Test::Base automatically adds:
use strict;
use warnings;
to all of your test scripts and Test::Base subclasses. A Spiffy feature indeed.
This module started its life with the horrible and ridicule inducing name "Test::Chunks". It was renamed to "Test::Base" with the hope that it would be seen for the very useful module that it has become. If you are switching from "Test::Chunks" to "Test::Base", simply substitute the concept and usage of "chunks" to "blocks".
Ingy döt Net <ingy@cpan.org>
Copyright 2005-2018. Ingy döt Net.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
See <http://www.perl.com/perl/misc/Artistic.html>
| 2018-04-19 | perl v5.34.0 |