hoxsl/test/apply/partial.xspec

<?xml version="1.0" encoding="utf-8"?>
<!--
  Tests partial function application

  Copyright (C) 2014 LoVullo Associates, Inc.

    This file is part of hoxsl.

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
-->

<description xmlns="http://www.jenitennison.com/xslt/xspec"
             xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
             xmlns:x="http://www.jenitennison.com/xslt/xspec"
             xmlns:f="http://www.lovullo.com/hoxsl/apply"
             xmlns:foo="http://www.lovullo.com/_junk"
             stylesheet="partial-test.xsl">

  <scenario label="f:partial">
    <variable name="fnref"
              select="foo:ternary()" />

    <variable name="args">
      <foo:parent>
        <foo:a />
        <foo:b />
        <foo:c />
      </foo:parent>
    </variable>


    <scenario label="given an empty argument list">
      <call function="f:partial">
        <param name="fnref" select="$fnref" />
        <param name="args"  select="()" />
      </call>

      <expect label="returns FNREF"
              test="$x:result[ 1 ] = $fnref" />

      <expect label="indicates that 0 arguments were partially applied"
              test="$x:result/@partial = 0" />

      <expect label="returns nothing else"
              test="count( $x:result ) = 1" />
    </scenario>


    <scenario label="given arguments fewer than function param count">
      <call function="f:partial">
        <param name="fnref" select="$fnref" />
        <param name="args"  select="$args/foo:a, $args/foo:b" />
      </call>

      <expect label="returns FNREF as first item in sequence"
              test="$x:result[ 1 ] = $fnref" />

      <expect label="indicates that N arguments were partially applied"
              test="$x:result/@partial = 2" />

      <expect label="returns each argument, ordered"
              test="$x:result[ 2 ] = $args/foo:a
                    and exists(
                      $x:result[ 2 ]/parent::foo:parent )
                    and $x:result[ 3 ] = $args/foo:b
                    and exists(
                      $x:result[ 3 ]/parent::foo:parent )" />
    </scenario>


    <scenario label="given arguments for all function params">
      <call function="f:partial">
        <param name="fnref" select="$fnref" />
        <param name="args"  select="1, 2, 3" />
      </call>

      <expect label="returns FNREF as first item in sequence"
              test="$x:result[ 1 ] = $fnref" />

      <!-- we checked previously for argument values; we assume here
           that it is working in this case...hopefully that is not
           wrong! -->
      <expect label="returns all arguments"
              test="count( $x:result ) = 4" />
    </scenario>


    <!-- partial applications should behave as their own functions -->
    <scenario label="partially applying partial application">
      <call function="f:partial">
        <param name="fnref" select="f:partial( $fnref, (1, 2) )" />
        <param name="args"  select="3" />
      </call>

      <expect label="returns FNREF as first item in sequence"
              test="$x:result[ 1 ] = $fnref" />

      <expect label="returns arguments from both partial applications"
              test="count( $x:result ) = 4" />

      <expect label="arguments are ordered with previous applications
                     first in sequence"
              test="$x:result[ 2 ] = 1
                    and $x:result[ 3 ] = 2
                    and $x:result[ 4 ] = 3" />
    </scenario>
  </scenario>


  <scenario label="f:is-partial">
    <scenario label="given a non-none">
      <call function="f:is-partial">
        <param name="fnref"
               select="5" />
      </call>

      <expect label="returns false()"
              test="$x:result = false()" />
    </scenario>


    <scenario label="given a non-fref node">
      <call function="f:is-partial">
        <param name="fnref">
          <foo:moo />
        </param>
      </call>

      <expect label="returns false()"
              test="$x:result = false()" />
    </scenario>


    <!-- this leaks implementation details :x -->
    <scenario label="given a non-fref node with spoofed attribute">
      <call function="f:is-partial">
        <param name="fnref">
          <foo:moo partial="5" f:partial="5" />
        </param>
      </call>

      <expect label="returns false()"
              test="$x:result = false()" />
    </scenario>


    <scenario label="given a valid fref, not partially applied">
      <call function="f:is-partial">
        <param name="fnref"
               select="foo:ternary()" />
      </call>

      <expect label="returns false()"
              test="$x:result = false()" />
    </scenario>


    <!-- if partially applied with no arguments, then it may as well
         not be; let's not alter the logic of callers just because it
         was called with no effect -->
    <scenario label="given a valid fref, partially applied with zero
                     arguments">
      <call function="f:is-partial">
        <param name="fnref"
               select="f:partial( foo:ternary(), () )" />
      </call>

      <expect label="returns false()"
              test="$x:result = false()" />
    </scenario>


    <scenario label="given a valid fref, partially applied with N>0
                     arguments, including argument sequence">
      <call function="f:is-partial">
        <param name="fnref"
               select="f:partial( foo:ternary(), (1, 2) )" />
      </call>

      <expect label="returns true()"
              test="$x:result = true()" />
    </scenario>


    <!-- caller may extract the function ref from the sequence and
         assert on that -->
    <scenario label="given a valid fref, partially applied with N>0
                     arguments, without argument sequence">
      <call function="f:is-partial">
        <param name="fnref"
               select="f:partial( foo:ternary(), (1, 2) )[ 1 ]" />
      </call>

      <expect label="returns true()"
              test="$x:result = true()" />
    </scenario>


    <!-- we still want to consider all arguments to be a partial
         application (consider it as producing a nullary
         function)—otherwise, the abstraction is broken -->
    <scenario label="given arguments for each parameter">
      <call function="f:is-partial">
        <param name="fnref"
               select="f:partial( foo:ternary(), (1, 2, 3) )" />
      </call>

      <expect label="returns true()"
              test="$x:result = true()" />
    </scenario>
  </scenario>
</description>