NAME Mock::Sub - Mock package, object and standard subroutines, with unit testing in mind. SYNOPSIS # see EXAMPLES for a full use case and caveats use Mock::Sub; # create the parent mock object my $mock = Mock::Sub->new; # mock some subs... all of the following are children under the # umbrella of the above $mock object we created my $foo = $mock->mock('Package::foo'); my $bar = $mock->mock('Package::bar'); # wait until the mocked sub is called Package::foo(); # then... $foo->name; # name of sub that's mocked $foo->called; # was the sub called? $foo->called_count; # how many times was it called? $foo->called_with; # array of params sent to sub # have the mocked sub return something when it's called (list or scalar). # See new() to find out how to set a return value once and have it used in # all child mocks $foo->return_value(1, 2, {a => 1}); my @return = Package::foo; # have the mocked sub perform an action (the side effect function receives # the parameters sent into the mocked sub). See new() to find out how to # set side_effect up once, and have it copied to all child mocks $foo->side_effect( sub { die "eval catch" if @_; } ); eval { Package::foo(1); }; like ($@, qr/eval catch/, "side_effect worked with params"); # extract the parameters the sub was called with (best if you know what # the original sub is expecting) my @args = $foo->called_with; # reset the mock object for re-use within the same scope (does not restore # the mocked sub) $foo->reset; # restore original functionality to the sub (we do this by default on # DESTROY()). This also calls reset() on the ojbect $foo->unmock; # re-mock a sub using the same object after unmocking (this is the only # time void context with mock() is permitted). Note that child mocks don't # take a sub parameter to mock() $foo->mock; # check if a sub is mocked my $state = $foo->state; # mock out a CORE:: function. Be warned that this *must* be done within # compile stage (BEGIN), and the function can NOT be unmocked prior # to the completion of program execution my ($mock, $caller); BEGIN { $mock = Mock::Sub->new; # core function caller() is now mocked permanently after the following line $caller = $mock->mock('caller'); }; $caller->return_value(55); caller(); # mocked caller() called DESCRIPTION Easy to use and very lightweight module for mocking out sub calls. Very useful for testing areas of your own modules where getting coverage may be difficult due to nothing to test against, and/or to reduce test run time by eliminating the need to call subs that you really don't want or need to test. EXAMPLE Here's a full example to get further coverage where it's difficult if not impossible to test certain areas of your code (eg: you have if/else statements, but they don't do anything but call other subs. You don't want to test the subs that are called, nor do you want to add statements to your code). Note that if the end subroutine you're testing is NOT Object Oriented (and you're importing them into your module that you're testing), you have to mock them as part of your own namespace (ie. instead of Other::first, you'd mock MyModule::first). # module you're testing: package MyPackage; use Other; use Exporter qw(import); @EXPORT_OK = qw(test); my $other = Other->new; sub test { my $arg = shift; if ($arg == 1){ # how do you test this... there's no return etc. $other->first(); } if ($arg == 2){ $other->second(); } } # your test file use MyPackage qw(test); use Mock::Sub; use Test::More tests => 2; my $mock = Mock::Sub->new; my $first = $mock->mock('Other::first'); my $second = $mock->mock('Other::second'); # coverage for first if() in MyPackage::test test(1); is ($first->called, 1, "1st if() statement covered"); # coverage for second if() test(2); is ($second->called, 1, "2nd if() statement covered"); MOCK OBJECT METHODS new(%opts) Instantiates and returns a new Mock::Sub object, ready to be used to start cteating mocked sub objects. Optional options: return_value Set this to have all mocked subs created with this mock object return anything you wish (accepts a single scalar only. See return_value() method to return a list and for further information). You can also set it in individual mocks only (see mock()). side_effect Set this in new() to have the side effect passed into all child mocks created with this object. See side_effect() method. mock('sub', %opts) Instantiates and returns a new mock object on each call (calling in void context is not permitted). 'sub' is the name of the subroutine to mock (requires full package name if the sub isn't in main::. The mocked sub will return undef if a return value isn't set, or a side effect doesn't return anything. Optional options: Both return_value and side_effect can be set in this method to individualize each mock object. Set in new to have all mock objects use the same configuration. There's also return_value() and side_effect() methods if you want to set, change or remove these values after instantiation. mocked_subs Returns a list of all subs that are currently mocked under the parent mock object. mocked_objects Returns a list of all sub objects underneath the parent mock object, regardless if its sub is currently mocked or not. mocked_state('Sub::Name') Returns whether a sub currently under the parent mock object is mocked or not. Croaks if there is no object with the sub name parameter. SUB OBJECT METHODS These methods are for the children mocked sub objects returned from the parent mock object. See "MOCK OBJECT METHODS" for methods related to the parent mock object. mock Re-mocks the sub within the object after calling unmock on it. unmock Restores the original functionality back to the sub, and runs reset() on the object. called Returns true if the sub being mocked has been called. called_count Returns the number of times the mocked sub has been called. called_with Returns an array of the parameters sent to the subroutine. croak()s if we're called before the mocked sub has been called. mocked_state Returns true if the sub the object refers to is currently mocked, and false if not. name Returns the full name of the sub being mocked, as entered into mock(). side_effect($cref) Add (or change/remove) a side effect after instantiation. Send in a code reference containing an action you'd like the mocked sub to perform (die() is useful for testing with eval()). The side effect function will receive all parameters sent into the mocked sub. You can use both side_effect() and return_value() params at the same time. side_effect will be run first, and then return_value. Note that if side_effect's last expression evaluates to any value whatsoever (even false), it will return that and return_value will be skipped. To work around this and have the side_effect run but still get the return_value thereafter, write your cref to evaluate undef as the last thing it does: sub { ...; undef; }. return_value Add (or change, delete) the mocked sub's return value after instantiation. Can be a scalar or list. Send in undef to remove a previously set value. reset Resets the functional parameters (return_value, side_effect), along with called() and called_count() back to undef/false. NOTES This module has a backwards parent-child relationship. To use, you create a mock object using "PARENT MOCK OBJECT METHODS" new and mock methods, thereafter, you use the returned mocked sub object METHODS to perform the work. The parent mock object retains certain information and statistics of the child mocked objects (and the subs themselves). To mock CORE::GLOBAL functions, you *must* initiate within a BEGIN block (see SYNOPSIS for details). It is important that if you mock a CORE sub, it can't and won't be returned to its original state until after the entire program process tree exists. Period. I didn't make this a Test:: module (although it started that way) because I can see more uses than placing it into that category. AUTHOR Steve Bertrand, BUGS Please report any bugs or requests at https://github.com/stevieb9/mock-sub/issues REPOSITORY https://github.com/stevieb9/mock-sub BUILD RESULTS Travis-CI: https://travis-ci.org/stevieb9/mock-sub CPAN Testers: http://matrix.cpantesters.org/?dist=Mock-Sub Coverage: https://coveralls.io/github/stevieb9/mock-sub SUPPORT You can find documentation for this module with the perldoc command. perldoc Mock::Sub ACKNOWLEDGEMENTS Python's MagicMock module. LICENSE AND COPYRIGHT Copyright 2016 Steve Bertrand. This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License. See http://dev.perl.org/licenses/ for more information.