NAME Test::Approx - compare two things for approximate equality SYNOPSIS use Test::Approx 'no_plan'; is_approx( 'abcd', 'abcd', 'equal strings' ); is_approx( 1234, 1234, 'equal integers' ); is_approx( 1.234, 1.234, 'equal decimal numbers' ); is_approx( '1.234000', '1.234', 'equal decimal numbers, extra zeros' ); is_approx( 1.0, 1, 'equal decimal number & integer' ); is_approx( 'abcdefgh', 'abcdefg', 'approx strings' ); is_approx( 1, 1.001, 'approx given decimal number & integer' ); is_approx( 51.60334, 51.603335, 'approx decimal numbers' ); # default Levenshtein edit tolerance is 5% of avg string length: is_approx( 'abcdefg', 'abcgfe', 'str tolerance' ); # fail # default difference tolerance is 5% of first number: is_approx( 1, 1.04, 'num tolerance' ); # fail is_approx( 1, 1.05, 'num tolerance' ); # fail # default difference tolerance is 5% of first integer, or 1: is_approx( 1, 2, 'int tolerance' ); # pass is_approx( 100, 105, 'int tolerance' ); # pass is_approx( 100, 106, 'int tolerance' ); # fail # you can set the tolerance yourself: is_approx( 'abcdefg', 'abcgfe', 'diff strings', '50%' ); # pass # you can set tolerance as a number too: is_approx( 'abcdefg', 'abcgfe', 'diff strings', 6 ); # you can force compare as string, number, or integer: is_approx_str( '1.001', '1.901', 'pass as string' ); is_approx_num( '1.001', '1.901', 'fail as num' ); is_approx_int( '1.001', '1.901', 'pass as int' ); # not rounded! DESCRIPTION This module lets you test if two things are *approximately* equal. Yes, that sounds a bit wrong at first - surely you know if they should be equal or not? But there are actually valid cases when you don't / can't know. This module is meant for those rare cases when close is good enough. FUNCTIONS is_approx( \$arg1, \$arg2 [, \$test_name, \$tolerance ] ) Tests if two scalars \$arg1 & \$arg2 are approximately equal by using one of: "is_approx_str", "is_approx_num" or is_approx_int. \$test_name defaults to 'arg1' =~ 'arg2'. \$tolerance is used to determine how different the scalars can be, it defaults to "5%". It can also be set as a number representing a threshold. To determine which: \$tolerance = '6%'; # threshold = calculated at 6% \$tolerance = 0.06; # threshold = 0.06 See the individual functions to determine how \$tolerance is used. is_approx_str( \$str1, \$str2 [, \$test_name, \$tolerance ] ) Tests if \$str1 is approximately equal to \$str2 by using Text::LevenshteinXS to compute the edit distance between the two strings, and comparing that to \$tolerance. \$tolerance is used to determine how many edits are allowed before the comparison test fails. If a percentage is given, the edit distance threshold will be set to "x%" of the *average lengths of the two strings*. eg: \$edit_threshold = int( \$x_percent * avg(length(\$str1), length(\$str2)) ); If that's less than 0, it defaults to 1. You can also pass \$tolerance in as an number. To avoid confusion: \$tolerance = '6%'; # threshold = 6% of avg strlen \$tolerance = 0.06; # threshold = int( 0.06 ) = 0 is_approx_num( \$num1, \$num2 [, \$test_name, \$tolerance ] ) Tests if \$num1 is approximately equal to \$num2 by calculating the distance between them and comparing that to \$tolerance. If \$tolerance is a percentage, the distance threshold will be set to "x%" of the *first number*, eg: \$threshold = \$x_percent * \$num1; Note that this can be 0 > \$t > 1, which is probably what you want. To avoid confusion: \$tolerance = '6%'; # threshold = 6% of \$num1 \$tolerance = 0.06; # threshold = 0.06 is_approx_int( \$int1, \$int2 [, \$test_name, \$tolerance ] ) Tests if \$int1 is approximately equal to \$int2 by calculating the distance between them and comparing that to \$tolerance. This is slightly different to "is_approx_num" as all fractions are removed. If \$tolerance is a percentage, the distance threshold will be set to "x%" of the *first integer*, or 1. Eg: \$threshold = int( \$x_percent * \$int1 ) || 1; To avoid confusion: \$tolerance = '6%'; # threshold = 6% of \$int1 \$tolerance = 0.06; # threshold = 0.06 EXPORTS "is_approx", "is_approx_str", "is_approx_num", "is_approx_int" AUTHOR Steve Purkis COPYRIGHT Copyright (c) 2008-2010 Steve Purkis. Released under the same terms as Perl itself. SEE ALSO Text::LevenshteinXS, Test::Builder