Try count(.//testdata) >0.

但是，如果您的上下文节点是 textdata 并且您想测试它是否有 somenode 子节点，我会写:

However if your context node is textdata and you want to test whether it has somenode child or not i would write:

  <xsl:if test="somenode"> 
    ...
  </xsl:if>

但我认为这不是你真正想要的.我认为您应该阅读编写 XSLT 样式表的不同技术(推/拉处理等).应用这些时，通常不需要这样的表达式，样式表变得更简单.

But I think that's not what you really want. I think you should read on different techniques of writing XSLT stylesheets (push/pull processing, etc.). When applying these, then such expressions are not usually necessary and stylesheets become simplier.