Test::Regexp(3)

NAME
Test::Regexp - Test your regular expressions

SYNOPSIS
 use Test::Regexp 'no_plan';

 match    subject      => "Foo",
          pattern      => qr /\w+/;

 match    subject      => "Foo bar",
          keep_pattern => qr /(?<first_word>\w+)\s+(\w+)/,
          captures     => [[first_word => 'Foo'], ['bar']];

 no_match subject      => "Baz",
          pattern      => qr /Quux/;

 $checker = Test::Regexp -> new -> init (
    keep_pattern => qr /(\w+)\s+\g{-1}/,
    name         => "Double word matcher",
 );

 $checker -> match    ("foo foo", ["foo"]);
 $checker -> no_match ("foo bar");

DESCRIPTION
This module is intended to test your regular expressions. Given a subject string and a regular expression (aka pattern), the module not only tests whether the regular expression complete matches the subject string, it performs a "utf8::upgrade" or "utf8::downgrade" on the subject string and performs the tests again, if necessary. Furthermore, given a pattern with capturing parenthesis, it checks whether all captures are present, and in the right order. Both named and unnamed captures are checked.

By default, the module exports two subroutines, "match" and "no_match". The latter is actually a thin wrapper around "match", calling it with "match => 0".

  "Complete matching"
A match is only considered to successfully match if the entire string is matched - that is, if $& matches the subject string. So:

  Subject    Pattern

  "aaabb"    qr /a+b+/     # Considered ok
  "aaabb"    qr /a+/       # Not considered ok

For efficiency reasons, when the matching is performed the pattern is actually anchored at the start. It's not anchored at the end as that would potentially influence the matching.

  UTF8 matching
Certain regular expression constructs match differently depending on whether UTF8 matching is in effect or not. This is only relevant if the subject string has characters with code points between 128 and 255, and no characters above 255 -- in such a case, matching may be different depending on whether the subject string has the UTF8 flag on or not. "Test::Regexp" detects such a case, and will then run the tests twice; once with the subject string "utf8::downgraded", and once with the subject string "utf8::upgraded".

  Number of tests
There's no fixed number of tests that is run. The number of tests depends on the number of captures, the number of different names of captures, and whether there is the need to up- or downgrade the subject string.

It is therefore recommended to use "use Text::Regexp tests => 'no_plan';". In a later version, "Test::Regexp" will use a version of "Test::Builder" that allows for nested tests.

Details

The number of tests is as follows:

If no match is expected ("no_match => 0", or "no_match" is used), only one test is performed.

Otherwise (we are expecting a match), if "pattern" is used, there will be three tests.

For "keep_pattern", there will be four tests, plus one tests for each capture, an additional test for each named capture, and a test for each name used in the set of named captures. So, if there are "N" captures, there will be at least "4 + N" tests, and at most "4 + 3 * N" tests.

If both "pattern" and "keep_pattern" are used, the number of tests add up.

If "Test::Regexp" decides to upgrade or downgrade, the number of tests double.

  "use" options
When using "Test::Regexp", there are a few options you can give it.

"tests => 'no_plan'", "tests => 123"
    The number of tests you are going to run. Since takes some work to figure out how many tests will be run, for now the recommendation is to use "tests => 'no_plan'".

"import => [methods]"
    By default, the subroutines "match" and "no_match" are exported. If you want to import a subset, use the "import" tag, and give it an arrayref with the names of the subroutines to import.

  "match"
The subroutine "match" is the workhorse of the module. It takes a number of named arguments, most of them optional, and runs one or more tests. It returns 1 if all tests were run successfully, and 0 if one or more tests failed. The following options are available:

"subject => STRING"
    The string against which the pattern is tested is passed to "match" using the "subject" option. It's an error to not pass in a subject.

"pattern => PATTERN", "keep_pattern => PATTERN"
    A pattern (aka regular expression) to test can be passed with one of "pattern" or "keep_pattern". The former should be used if the pattern does not have any matching parenthesis; the latter if the pattern does have capturing parenthesis. If both "pattern" and "keep_pattern" are provided, the subject is tested against both. It's an error to not give either "pattern" or "keep_pattern".

"captures => [LIST]"
    If a regular expression is passed with "keep_pattern" you should pass in a list of captures using the "captures" option.

    This list should contain all the captures, in order. For unnamed captures, this should just be the string matched by the capture; for a named capture, this should be a two element array, the first element being the name of the capture, the second element the capture. Named and unnamed captures may be mixed, and the same name for a capture may be repeated.

    Example:

     match  subject      =>  "Eland Wapiti Caribou",
            keep_pattern =>  qr /(\w+)\s+(?<a>\w+)\s+(\w+)/,
            captures     =>  ["Eland", [a => "Wapiti"], "Caribou"];

"name => NAME"
    The "name" of the test. It's being used in the test comment.

"comment => NAME"
    An alternative for "name". If both are present, "comment" is used.

"utf8_upgrade => 0", "utf8_downgrade => 0"
    As explained in "UTF8 matching", "Test::Regexp" detects whether a subject may provoke different matching depending on its UTF8 flag, and then it "utf8::upgrades" or "utf8::downgrades" the subject string and runs the test again. Setting "utf8_upgrade" to 0 prevents "Test::Regexp" from downgrading the subject string, while setting "utf8_upgrade" to 0 prevents "Test::Regexp" from upgrading the subject string.

"match => BOOLEAN"
    By default, "match" assumes the pattern should match. But it also important to test which strings do not match a regular expression. This can be done by calling "match" with "match => 0" as parameter. (Or by calling "no_match" instead of "match"). In this case, the test is a failure if the pattern completely matches the subject string. A "captures" argument is ignored.

"reason => STRING"
    If the match is expected to fail (so, when "match => 0" is passed, or if "no_match" is called), a reason may be provided with the "reason" option. The reason is then printed in the comment of the test.

"test => STRING"
    If the match is expected to pass (when "match" is called, without "match" being false), and this option is passed, a message is printed indicating what this specific test is testing (the argument to "test").

"todo => STRING"
    If the "todo" parameter is used (with a defined value), the tests are assumed to be TODO tests. The argument is used as the TODO message.

"full_text => BOOL"
    By default, long test messages are truncated; if a true value is passed, the message will not get truncated.

"escape => INTEGER"
    Controls how non-ASCII and non-printables are displayed in generated test messages:

    0   No characters are escape, everything is displayed as is.

    1   Show newlines, linefeeds and tabs using their usual escape sequences ("\n", "\r", and "\t").

    2   Show any character outside of the printable ASCII characters as named escapes ("\N{UNICODE NAME}"), or a hex escape if the unicode name is not found ("\x{XX}"). This is the default if "-CO" is not in effect ("${^UNICODE}" is false).

        Newlines, linefeeds and tabs are displayed as above.

    3   Show any character outside of the printable ASCII characters as hext escapes ("\x{XX}").

        Newlines, linefeeds and tabs are displayed as above.

    4   Show the non-printable ASCII characters as hex escapes ("\x{XX}"); any non-ASCII character is displayed as is. This is the default if "-CO" is in effect ("${^UNICODE}" is true).

        Newlines, linefeeds and tabs are displayed as above.

"no_keep_message => BOOL"
    If matching against a keeping pattern, a message "(with -Keep)" is added to the comment. Setting this parameter suppresses this message. Mostly useful for "Regexp::Common510".

  "no_match"
Similar to "match", except that it tests whether a pattern does not match a string. Accepts the same arguments as "match", except for "match".

  OO interface
Since one typically checks a pattern with multiple strings, and it can be tiresome to repeatedly call "match" or "no_match" with the same arguments, there's also an OO interface. Using a pattern, one constructs an object and can then repeatedly call the object to match a string.

To construct and initialize the object, call the following:

 my $checker = Test::Regexp -> new -> init (
    pattern      => qr  /PATTERN/,
    keep_pattern => qr /(PATTERN)/,
    ...
 );

"init" takes exactly the same arguments as "match", with the exception of "subject" and "captures". To perform a match, all "match" (or "no_match") on the object. The first argument should be the subject the pattern should match against (see the "subject" argument of "match" discussed above). If there is a match against a capturing pattern, the second argument is a reference to an array with the matches (see the "captures" argument of "match" discussed above).

Both "match" and "no_match" can take additional (named) arguments, identical to the none-OO "match" and "no_match" routines.

RATIONALE
The reason "Test::Regexp" was created is to aid testing for the rewrite of "Regexp::Common".

DEVELOPMENT
The current sources of this module are found on github, <git://github.com/Abigail/Test-Regexp.git>.

AUTHOR
Abigail <mailto:test-regexp@abigail.be>.

COPYRIGHT and LICENSE
Copyright (C) 2009 by Abigail

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

INSTALLATION
To install this module, run, after unpacking the tar-ball, the following commands:

   perl Makefile.PL
   make
   make test
   make install