NAME

       "Test::ExpectAndCheck" - "expect/check"-style unit testing with object methods

SYNOPSIS

          use Test::More;
          use Test::ExpectAndCheck;

          my ( $controller, $mock ) = Test::ExpectAndCheck->create;

          {
             $controller->expect( act => 123, 45 )
                ->will_return( 678 );

             is( $mock->act( 123, 45 ), 678, '$mock->act returns result' );

             $controller->check_and_clear( '->act' );
          }

          done_testing;

DESCRIPTION

       This package creates objects that assist in writing unit tests with mocked object
       instances. Each mock instance will expect to receive a given list of method calls. Each
       method call is checked that it received the right arguments, and will return a prescribed
       result. At the end of each test, each object is checked to ensure all the expected methods
       were called.

METHODS

   create
          ( $controller, $mock ) = Test::ExpectAndCheck->create;

       Objects are created in "entangled pairs" by the "create" method. The first object is
       called the "controller", and is used by the unit testing script to set up what method
       calls are to be expected, and what their results shall be.  The second object is the
       "mock", the object to be passed to the code being tested, on which the expected method
       calls are (hopefully) invoked. It will have whatever interface is implied by the method
       call expectations.

   expect
          $exp = $controller->expect( $method, @args );

       Specifies that the mock will expect to receive a method call of the given name, with the
       given arguments.

       The argument values are compared using "cmp_deeply" in Test::Deep. Values can be specified
       literally, or using any of the "Special Comparisons" defined by Test::Deep.

       The test script can call the "will_return" or "will_throw" methods on the expectation to
       set what the result of invoking this method will be.

   whenever
          $exp = $controller->whenever( $method, @args );

       Since version 0.05.

       Specifies that the mock might expect to receive method calls of the given name with the
       given arguments. These expectations are not expired once called, nor do they expect to be
       called in any particular order. Furthermore it is not a test failure for one of these not
       to be invoked at all.

       These expectations do not directly form part of the test assertions checked by the
       "check_and_clear" method, but they may be useful to assist the code under test, such as
       providing support behaviours that it may rely on but would make the test script too
       fragile if spelled out in full using a regular "expect".

       These expectations are only used as a fallback mechanism, if the next real "expect"-based
       expectation does not match a method call. Individual special cases can still be set up
       using "expect" even though a "whenever" exists that might also match it.

       As with "expect", the argument values are compared using "Test::Deep", and results can be
       set with "will_return" or "will_throw".

   check_and_clear
          $controller->check_and_clear( $name );

       Checks that by now, every expected method has been called, and emits a new test output
       line via Test::Builder. Regardless, the expectations are also cleared out ready for the
       start of the next test.

EXPECTATIONS

       Each value returned by the "expect" method is an "expectation", an object that represents
       one expected method call, the arguments it should receive, and the return value it should
       provide.

   will_return
          $exp->will_return( @result );

       Since version 0.04.

       Sets the result that will be returned by this method call.

       This method used to be named "returns", which should be avoided in new code.  Uses of the
       old name will print a deprecation warning.

   will_return_using
          $exp->will_return_using( sub ($args) { ... } );

       Since version 0.05.

       Sets the result that will be returned, calculated by invoking the code.

       The code block is invoked at the time that a result is needed. It is invoked with an array
       reference containing the arguments to the original method call.  This is especially useful
       for expectations created using "whenever".

       Since version 0.06 the code block is passed a reference to the caller's actual arguments
       array, and therefore can modify values in it if required - e.g. when trying to mock
       functions such as "open()" or "sysread()" which modify lvalues passed in as arguments.

       There is no corresponding "will_throw_using", but an exception thrown by this code will be
       seen by the calling code.

   will_throw
          $exp->will_throw( $e );

       Since version 0.04.

       Sets the exception that will be thrown by this method call.

       This method used to be named "throws", which should be avoided in new code.

   will_also
          $exp->will_also( sub { ... } );

       Since version 0.04.

       Adds extra code which is run when the expected method is called, in addition to generating
       the result value or exception.

       When invoked, the code body is invoked in void context with no additional arguments.

   indefinitely
          $exp->indefinitely;

       Since version 0.05.

       On an expectation created using "whenever", this expectation will not be cleared by
       "check_and_clear", effectively establishing its effects for the entire lifetime of the
       test script.

       On an expectation created using "expect" this has no effect; such an expectation will
       still be cleared as usual.

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>