source: project/wiki/eggref/4/dummy-user @ 27371

== dummy-user

Simulates user input for testing interactive command-line programs.

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=== Author
Matt Gushee

=== API

==== make-dummy-user
<procedure>(make-dummy-user STRINGS)</procedure>

Given a list of strings representing a sequence of user input, this procedure returns a {{DUMMY-USER}} closure, which responds to the following messages:

 (USER 'input)
 (USER 'output)

These calls return, respectively, an input and an output port. Generally you do not need to use them directly; they are used by {{with-dummy-user}} to rebind {{stdin}} and {{stdout}}.

 (USER 'reset)

Resets the dummy user to its initial state, allowing repeated tests with the same data.

 (USER 'dump)

Returns a list of all data received from and sent to the test program, in the form '((program: STRING) (user: STRING) ...).

==== with-dummy-user

<procedure>(with-dummy-user USER THUNK [RETURN-RESULT])</procedure>

Tests a program with a dummy user. The {{USER}} argument should be a closure such as that produced by {{make-dummy-user}}. {{THUNK}} is a procedure of no arguments that runs the program you wish to test, with {{stdin}} and {{stdout}} bound to the ports provided by {{USER}}. By default, this procedure calls {{(USER 'dump)}} and returns the result of that call. However, you may provide your own {{RETURN-RESULT}} procedure (with 0 arguments) to cause other data to be returned (e.g. the inputs collected by your program).

=== Examples

<enscript highlight="scheme">
  (use dummy-user)

  (define my-results #f)

  (define (test-prog)
    (let ((collected-data (make-queue)))
      (display "Name: ")
      (queue-add! collected-data (cons 'name (read-line)))
      (display "Age: ")
      (queue-add! collected-data (cons 'age (read-line)))
      (display "Phone: ")
      (queue-add! collected-data (cons 'phone (read-line)))
      (print "OK, thanks!")
      collected-data))

  (define my-dummy (make-dummy-user '("Jenny" "24" "867-5309")))

  (pp (with-dummy-user my-dummy test-prog))

  ;;; Should print: ((program: "Name: ") (user: "Jenny") (program: "Age: ") (user: "24")
  ;;;                (program: "Phone: ") (user: "867-5309") (program: "OK, Thanks!") (program: "\n"))

  (my-dummy 'reset)

  (pp (with-dummy-user
        my-dummy
        (lambda () (set! my-results (test-prog)))
        (lambda () (queue->list my-results))))
  
  ;;; Should print: ((name . "Jenny") (age . "24") (phone . "867-5309"))
</enscript>

=== Requirements
None.


=== License

Copyright (c) 2012, Matthew C. Gushee
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:


    Redistributions of source code must retain the above copyright notice,
    this list of conditions and the following disclaimer.

    Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.
    
    Neither the name of the author nor the names of its contributors may be
    used to endorse or promote products derived from this software without
    specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.


=== Version history

==== version 0.1
Initial release