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MockModule.pm
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package Test::MockModule; use warnings; use strict qw/subs vars/; use vars qw/$VERSION/; use Scalar::Util qw/reftype weaken/; use Carp; use SUPER; $VERSION = '0.170.0'; my %mocked; sub new { my $class = shift; my ($package, %args) = @_; if ($package && (my $existing = $mocked{$package})) { return $existing; } croak "Cannot mock $package" if $package && $package eq $class; unless (_valid_package($package)) { $package = 'undef' unless defined $package; croak "Invalid package name $package"; } unless ($args{no_auto} || ${"$package\::VERSION"}) { (my $load_package = "$package.pm") =~ s{::}{/}g; TRACE("$package is empty, loading $load_package"); require $load_package; } TRACE("Creating MockModule object for $package"); my $self = bless { _package => $package, _mocked => {}, }, $class; $mocked{$package} = $self; weaken $mocked{$package}; return $self; } sub DESTROY { my $self = shift; $self->unmock_all; } sub get_package { my $self = shift; return $self->{_package}; } sub redefine { my ($self, @mocks) = (shift, @_); while ( my ($name, $value) = splice @mocks, 0, 2 ) { my $sub_name = $self->_full_name($name); my $coderef = *{$sub_name}{'CODE'}; next if 'CODE' eq ref $coderef; if ( $sub_name =~ qr{^(.+)::([^:]+)$} ) { my ( $pkg, $sub ) = ( $1, $2 ); my $object = bless {}, $pkg; next if $object->can( $sub ); } if ('CODE' ne ref $coderef) { croak "$sub_name does not exist!"; } } return $self->mock(@_); } sub mock { my $self = shift; while (my ($name, $value) = splice @_, 0, 2) { my $code = sub { }; if (ref $value && reftype $value eq 'CODE') { $code = $value; } elsif (defined $value) { $code = sub {$value}; } TRACE("$name: $code"); croak "Invalid subroutine name: $name" unless _valid_subname($name); my $sub_name = _full_name($self, $name); if (!$self->{_mocked}{$name}) { TRACE("Storing existing $sub_name"); $self->{_mocked}{$name} = 1; if (defined &{$sub_name}) { $self->{_orig}{$name} = \&$sub_name; } else { $self->{_orig}{$name} = undef; } } TRACE("Installing mocked $sub_name"); _replace_sub($sub_name, $code); } } sub noop { my $self = shift; $self->mock($_,1) for @_; } sub original { my $self = shift; my ($name) = @_; return carp _full_name($self, $name) . " is not mocked" unless $self->{_mocked}{$name}; return defined $self->{_orig}{$name} ? $self->{_orig}{$name} : $self->{_package}->super($name); } sub unmock { my $self = shift; for my $name (@_) { croak "Invalid subroutine name: $name" unless _valid_subname($name); my $sub_name = _full_name($self, $name); unless ($self->{_mocked}{$name}) { carp $sub_name . " was not mocked"; next; } TRACE("Restoring original $sub_name"); _replace_sub($sub_name, $self->{_orig}{$name}); delete $self->{_mocked}{$name}; delete $self->{_orig}{$name}; } return $self; } sub unmock_all { my $self = shift; foreach (keys %{$self->{_mocked}}) { $self->unmock($_); } } sub is_mocked { my $self = shift; my ($name) = shift; return $self->{_mocked}{$name}; } sub _full_name { my ($self, $sub_name) = @_; sprintf "%s::%s", $self->{_package}, $sub_name; } sub _valid_package { defined($_[0]) && $_[0] =~ /^[a-z_]\w*(?:::\w+)*$/i; } sub _valid_subname { $_[0] =~ /^[a-z_]\w*$/i; } sub _replace_sub { my ($sub_name, $coderef) = @_; no warnings 'redefine'; no warnings 'prototype'; if (defined $coderef) { *{$sub_name} = $coderef; } else { TRACE("removing subroutine: $sub_name"); my ($package, $sub) = $sub_name =~ /(.*::)(.*)/; my %symbols = %{$package}; # save a copy of all non-code slots my %slot; foreach (qw(ARRAY FORMAT HASH IO SCALAR)) { next unless defined(my $elem = *{$symbols{$sub}}{$_}); $slot{$_} = $elem; } # clear the symbol table entry for the subroutine undef *$sub_name; # restore everything except the code slot return unless keys %slot; foreach (keys %slot) { *$sub_name = $slot{$_}; } } } # Log::Trace stubs sub TRACE {} sub DUMP {} 1; =pod =head1 NAME Test::MockModule - Override subroutines in a module for unit testing =head1 SYNOPSIS use Module::Name; use Test::MockModule; { my $module = Test::MockModule->new('Module::Name'); $module->mock('subroutine', sub { ... }); Module::Name::subroutine(@args); # mocked #Same effect, but this will die() if other_subroutine() #doesn't already exist, which is often desirable. $module->redefine('other_subroutine', sub { ... }); } Module::Name::subroutine(@args); # original subroutine # Working with objects use Foo; use Test::MockModule; { my $mock = Test::MockModule->new('Foo'); $mock->mock(foo => sub { print "Foo!\n"; }); my $foo = Foo->new(); $foo->foo(); # prints "Foo!\n" } =head1 DESCRIPTION C<Test::MockModule> lets you temporarily redefine subroutines in other packages for the purposes of unit testing. A C<Test::MockModule> object is set up to mock subroutines for a given module. The object remembers the original subroutine so it can be easily restored. This happens automatically when all MockModule objects for the given module go out of scope, or when you C<unmock()> the subroutine. =head1 METHODS =over 4 =item new($package[, %options]) Returns an object that will mock subroutines in the specified C<$package>. If there is no C<$VERSION> defined in C<$package>, the module will be automatically loaded. You can override this behaviour by setting the C<no_auto> option: my $mock = Test::MockModule->new('Module::Name', no_auto => 1); =item get_package() Returns the target package name for the mocked subroutines =item is_mocked($subroutine) Returns a boolean value indicating whether or not the subroutine is currently mocked =item mock($subroutine =E<gt> \E<amp>coderef) Temporarily replaces one or more subroutines in the mocked module. A subroutine can be mocked with a code reference or a scalar. A scalar will be recast as a subroutine that returns the scalar. The following statements are equivalent: $module->mock(purge => 'purged'); $module->mock(purge => sub { return 'purged'}); When dealing with references, things behave slightly differently. The following statements are B<NOT> equivalent: # Returns the same arrayref each time, with the localtime() at time of mocking $module->mock(updated => [localtime()]); # Returns a new arrayref each time, with up-to-date localtime() value $module->mock(updated => sub { return [localtime()]}); The following statements are in fact equivalent: my $array_ref = [localtime()] $module->mock(updated => $array_ref) $module->mock(updated => sub { return $array_ref }); However, C<undef> is a special case. If you mock a subroutine with C<undef> it will install an empty subroutine $module->mock(purge => undef); $module->mock(purge => sub { }); rather than a subroutine that returns C<undef>: $module->mock(purge => sub { undef }); You can call C<mock()> for the same subroutine many times, but when you call C<unmock()>, the original subroutine is restored (not the last mocked instance). B<MOCKING + EXPORT> If you are trying to mock a subroutine exported from another module, this may not behave as you initially would expect, since Test::MockModule is only mocking at the target module, not anything importing that module. If you mock the local package, or use a fully qualified function name, you will get the behavior you desire: use Test::MockModule; use Test::More; use POSIX qw/strftime/; my $posix = Test::MockModule->new("POSIX"); $posix->mock("strftime", "Yesterday"); is strftime("%D", localtime(time)), "Yesterday", "`strftime` was mocked successfully"; # Fails is POSIX::strftime("%D", localtime(time)), "Yesterday", "`strftime` was mocked successfully"; # Succeeds my $main = Test::MockModule->new("main", no_auto => 1); $main->mock("strftime", "today"); is strftime("%D", localtime(time)), "today", "`strftime` was mocked successfully"; # Succeeds If you are trying to mock a subroutine that was exported into a module that you're trying to test, rather than mocking the subroutine in its originating module, you can instead mock it in the module you are testing: package MyModule; use POSIX qw/strftime/; sub minus_twentyfour { return strftime("%a, %b %d, %Y", localtime(time - 86400)); } package main; use Test::More; use Test::MockModule; my $posix = Test::MockModule->new("POSIX"); $posix->mock("strftime", "Yesterday"); is MyModule::minus_twentyfour(), "Yesterday", "`minus-twentyfour` got mocked"; # fails my $mymodule = Test::MockModule->new("MyModule", no_auto => 1); $mymodule->mock("strftime", "Yesterday"); is MyModule::minus_twentyfour(), "Yesterday", "`minus-twentyfour` got mocked"; # succeeds =item redefine($subroutine) The same behavior as C<mock()>, but this will preemptively check to be sure that all passed subroutines actually exist. This is useful to ensure that if a mocked module's interface changes the test doesn't just keep on testing a code path that no longer behaves consistently with the mocked behavior. Note that redefine is also now checking if one of the parent provides the sub and will not die if it's available in the chain. =item original($subroutine) Returns the original (unmocked) subroutine Here is a sample how to wrap a function with custom arguments using the original subroutine. This is useful when you cannot (do not) want to alter the original code to abstract one hardcoded argument pass to a function. package MyModule; sub sample { return get_path_for("/a/b/c/d"); } sub get_path_for { ... # anything goes there... } package main; use Test::MockModule; my $mock = Test::MockModule->new("MyModule"); # replace all calls to get_path_for using a different argument $mock->redefine("get_path_for", sub { return $mock->original("get_path_for")->("/my/custom/path"); }); # or $mock->redefine("get_path_for", sub { my $path = shift; if ( $path && $path eq "/a/b/c/d" ) { # only alter calls with path set to "/a/b/c/d" return $mock->original("get_path_for")->("/my/custom/path"); } else { # preserve the original arguments return $mock->original("get_path_for")->(@_); } }); =item unmock($subroutine [, ...]) Restores the original C<$subroutine>. You can specify a list of subroutines to C<unmock()> in one go. =item unmock_all() Restores all the subroutines in the package that were mocked. This is automatically called when all C<Test::MockObject> objects for the given package go out of scope. =item noop($subroutine [, ...]) Given a list of subroutine names, mocks each of them with a no-op subroutine. Handy for mocking methods you want to ignore! # Neuter a list of methods in one go $module->noop('purge', 'updated'); =back =over 4 =item TRACE A stub for Log::Trace =item DUMP A stub for Log::Trace =back =head1 SEE ALSO L<Test::MockObject::Extends> L<Sub::Override> =head1 AUTHORS Current Maintainer: Geoff Franks <gfranks@cpan.org> Original Author: Simon Flack E<lt>simonflk _AT_ cpan.orgE<gt> =head1 COPYRIGHT Copyright 2004 Simon Flack E<lt>simonflk _AT_ cpan.orgE<gt>. All rights reserved You may distribute under the terms of either the GNU General Public License or the Artistic License, as specified in the Perl README file. =cut