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Test::LongString(3) User Contributed Perl Documentation Test::LongString(3)

NAME

Test::LongString - tests strings for equality, with more helpful failures

SYNOPSIS

    use Test::More tests => 1;
    use Test::LongString;
    like_string( $html, qr/(perl|cpan)\.org/ );
    #     Failed test (html-test.t at line 12)
    #          got: "<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Trans"...
    #       length: 58930
    #     doesn't match '(?-xism:(perl|cpan)\.org)'

DESCRIPTION

This module provides some drop-in replacements for the string comparison functions of Test::More, but which are more suitable when you test against long strings. If you've ever had to search for text in a multi-line string like an HTML document, or find specific items in binary data, this is the module for you.

FUNCTIONS

is_string( $string, $expected [, $label ] )

"is_string()" is equivalent to "Test::More::is()", but with more helpful diagnostics in case of failure.

  • It doesn't print the entire strings in the failure message.
  • It reports the lengths of the strings that have been compared.
  • It reports the length of the common prefix of the strings.
  • It reports the line and column the strings started to differ on.
  • In the diagnostics, non-ASCII characters are escaped as "\x{xx}".

For example:

    is_string( $soliloquy, $juliet );
    #     Failed test (soliloquy.t at line 15)
    #          got: "To be, or not to be: that is the question:\x{0a}Whether"...
    #       length: 1490
    #     expected: "O Romeo, Romeo,\x{0a}wherefore art thou Romeo?\x{0a}Deny thy"...
    #       length: 154
    #     strings begin to differ at char 1 (line 1 column 1)

is_string_nows( $string, $expected [, $label ] )

Like "is_string()", but removes whitespace (in the "\s" sense) from the arguments before comparing them.

like_string( $string, qr/regex/ [, $label ] )

unlike_string( $string, qr/regex/ [, $label ] )

"like_string()" and "unlike_string()" are replacements for "Test::More:like()" and "unlike()" that only print the beginning of the received string in the output. Unfortunately, they can't print out the position where the regex failed to match.

    like_string( $soliloquy, qr/Romeo|Juliet|Mercutio|Tybalt/ );
    #     Failed test (soliloquy.t at line 15)
    #          got: "To be, or not to be: that is the question:\x{0a}Whether"...
    #       length: 1490
    #     doesn't match '(?-xism:Romeo|Juliet|Mercutio|Tybalt)'

contains_string( $string, $substring [, $label ] )

"contains_string()" searches for $substring in $string. It's the same as "like_string()", except that it's not a regular expression search.

    contains_string( $soliloquy, "Romeo" );
    #     Failed test (soliloquy.t at line 10)
    #         searched: "To be, or not to be: that is the question:\x{0a}Whether"...
    #   and can't find: "Romeo"

As of version 0.12, "contains_string()" will also report the Longest Common SubString (LCSS) found in $string and, if the LCSS is short enough, the surroundings will also be shown under LCSS Context. This should help debug tests for really long strings like HTML output, so you'll get something like:

   contains_string( $html, '<div id="MainContent">' );
   #   Failed test at t/foo.t line 10.
   #     searched: "<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Stric"...
   #   can't find: "<div id="MainContent">"
   #         LCSS: "ainContent""
   # LCSS context: "dolor sit amet</span>\x{0a}<div id="mainContent" class="

You can turn off LCSS reporting by setting $Test::LongString::LCSS to 0, or by specifying an argument to "use":

    use Test::LongString lcss => 0;

lacks_string( $string, $substring [, $label ] )

"lacks_string()" makes sure that $substring does NOT exist in $string. It's the same as "like_string()", except that it's not a regular expression search.

    lacks_string( $soliloquy, "slings" );
    #     Failed test (soliloquy.t at line 10)
    #         searched: "To be, or not to be: that is the question:\x{0a}Whether"...
    #        and found: "slings"
    #      at position: 147 (line 3 column 4)

CONTROLLING OUTPUT

By default, only the first 50 characters of the compared strings are shown in the failure message. This value is in $Test::LongString::Max, and can be set at run-time.

You can also set it by specifying an argument to "use":

    use Test::LongString max => 100;

When the compared strings begin to differ after a large prefix, Test::LongString will not print them from the beginning, but will start at the middle, more precisely at $Test::LongString::Context characters before the first difference. By default this value is 10 characters. If you want Test::LongString to always print the beginning of compared strings no matter where they differ, undefine $Test::LongString::Context.

When computing line numbers this module uses "\n" to count line endings. This may not be appropriate for strings on your platform, and can be overridden by setting the $Test::LongString::EOL variable to a suitable regular expression (either a reference to a regular expression or a string that can be interpolated into a regular expression.)

You can also set it by specifying an argument to "use":

    use Test::LongString eol => "\x{0a}\x{0c}";

AUTHOR

Written by Rafael Garcia-Suarez. Thanks to Mark Fowler (and to Joss Whedon) for the inspirational Acme::Test::Buffy. Thanks to Andy Lester for lots of patches.

This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.

A git repository for this module is available at

    git://github.com/rgs/Test-LongString.git

and the project page at

    http://github.com/rgs/Test-LongString

SEE ALSO

Test::Builder, Test::Builder::Tester, Test::More.

2021-08-09 perl v5.32.1