Arithmetic operation does not work when used in with-param in xsl

Question

Could someone please explain why the following does not work.

Here is the xml:

<?xml version="1.0" ?>
<testsuites>
    <testsuite errors="0" failures="0" name="test_ui_orchestration" tests="10" time="90.190"/>
    <testsuite errors="1" failures="0" name="test_ui_tables" tests="13" time="1115.771"/>
    <testsuite errors="0" failures="3" name="test_ui_dashboard" tests="18" time="116.397"/>
</testsuites>

I want to calculate total number of tests, total pass and fail. I have a problem getting total number of failures (failures + errors) and total number of pass (for simplicity: tests - failures). I call the same xml-template for calculating totals passing in different values using "with-param" as follows (section within "Calculate sums" comments):

<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match="/testsuites">
  <html>
  <body>

  <!-- Calculate sums start -->
  <xsl:variable name="allSum">
    <xsl:call-template name="testsSum">
      <xsl:with-param name="numTests" select="testsuite/@tests"/>
    </xsl:call-template>
  </xsl:variable>
    <xsl:variable name="failedSum">
      <xsl:call-template name="testsSum">
        <xsl:with-param name="numTests" select="testsuite/@failures"/>
      </xsl:call-template>
    </xsl:variable>
    <xsl:variable name="errorSum">
      <xsl:call-template name="testsSum">
        <xsl:with-param name="numTests" select="testsuite/@errors"/>
      </xsl:call-template>
    </xsl:variable>
    <xsl:variable name="failederrorSum">
      <xsl:call-template name="testsSum">
        <xsl:with-param name="numTests" select="testsuite/@failures + testsuite/@errors"/>
      </xsl:call-template>
    </xsl:variable>
  <!-- Calculate sums ends -->

  <h2>Test Results</h2>
  <table border="1">
    <tr bgcolor="#9acd32">
      <th>Test Area</th>
      <th>Total</th>
      <th>Pass</th>
      <th>Fail</th>
      <th>Error</th>
      <th>Fail and Error</th>
    </tr>

    <xsl:for-each select="testsuite">
          <tr>
              <td><xsl:value-of select="@name"/></td>
              <td><xsl:value-of select="@tests"/></td>
              <td><xsl:value-of select="@tests - (@failures + @errors)"/></td>
              <td><xsl:value-of select="@failures"/></td>
              <td><xsl:value-of select="@errors"/></td>
              <td><xsl:value-of select="@failures + @errors"/></td>
              <td> </td>
          </tr>
    </xsl:for-each>

    <tr>
      <td><b>All Tests</b></td>
      <td><xsl:value-of select="$allSum"/></td>
      <td>foo</td>
        <!--
      <td><xsl:value-of select="$passedSum"/></td>
      -->
      <td><xsl:value-of select="$failedSum"/></td>
      <td><xsl:value-of select="$errorSum"/></td>
      <td><xsl:value-of select="$failederrorSum"/></td>
      <td></td>
    </tr>

  </table>
  </body>
  </html>
</xsl:template>

<xsl:template name="testsSum">
  <xsl:param name="numTests"/>
    <xsl:choose>
      <xsl:when test="$numTests">
        <xsl:variable name="recursive_result">
          <xsl:call-template name="testsSum">
            <xsl:with-param name="numTests" select="$numTests[position() > 1]"/>
          </xsl:call-template>
        </xsl:variable>
        <xsl:value-of select="number($numTests[1]) + $recursive_result"/>
      </xsl:when>
      <xsl:otherwise><xsl:value-of select="0"/></xsl:otherwise>
    </xsl:choose>
  </xsl:template>
</xsl:stylesheet>

This produces the following output for the sums (full output is at the end of this post):

41 3 1 0

while it should be:

41 3 1 4

Each individual sum works fine, the corresponding attribute is found. However, when I attempt to add two attributes and pass that to the sum template, it does not work as expected.

It gets worse. The code for generating total passed tests is:

<xsl:variable name="passedSum">
    <xsl:call-template name="testsSum">
        <xsl:with-param name="numTests"
                select="testsuite/@tests - testsuite/@failures"/>
    </xsl:call-template>
</xsl:variable>

When the above code is enabled, I get the following error:

Failed to evaluate the expression of variable 'numTests'

I've been searching online and understand that the "select" of "with-param" accepts "An XPath expression that defines the value of the parameter" (from w3schools). An XPath expression can contain arithmetic operations (http://www.w3schools.com/xpath/xpath_operators.asp), so why do the above fail?

Here is full output of the xsl transformation:

Test Area               Total   Pass    Fail    Error   Fail and Error
----------------------------------------------------------------------
test_ui_orchestration   10      10      0       0       0
test_ui_tables          13      12      0       1       1   
test_ui_dashboard       18      15      3       0       3
----------------------------------------------------------------------  
All Tests               41      foo     3       1       0

Here is the expected output of the xsl transformation (modified values marked with *):

Test Area               Total   Pass    Fail    Error   Fail and Error
----------------------------------------------------------------------
test_ui_orchestration   10      10      0       0       0
test_ui_tables          13      12      0       1       1   
test_ui_dashboard       18      15      3       0       3
----------------------------------------------------------------------  
All Tests               41      37*     3       1       4*

Michael Kay Michael Kay · Accepted Answer · 2013-11-13T08:23:29

As Stormtroopr says, you haven't shown us the part of the XSLT code that sets the context, and the fact that you left this out suggests you haven't understood how important context is in XSLT. If your XPath expressions select anything at all, we can probably assume that the context item is the testsuites element, in which case path expressions such as testsuite/@failures all select multiple values (a node set containing several attribute nodes). That's fine if the template you are calling expects a node-set. But when you use a node-set containing multiple nodes as input to an arithmetic operation, then:

(a) In XSLT 1.0 it uses the first node in the node-set and ignores the others

(b) In XSLT 2.0 you get a type error saying that what you are doing makes no sense.

Since you're getting an error, I assume you are using XSLT 2.0, though it doesn't seem a very helpful error message (which XSLT processor are you using?)

As for fixing the problem, I can't help with that because you haven't explained what you are trying to achieve - I can't reverse-engineer the requirements from incorrect code.

Arithmetic operation does not work when used in with-param in xsl

3 Answers

This stylesheet applied to the input XML:

Gives this output:

Which looks like this: