Is possible to write Xpath check to validate that class has only one exact annotation?

[MrStille]

I need to create a rule that every class having a word Tests in its name must have annotations @Epic ?
Is it possible to do it with Xpath ?
I tried to use count - but it did not work, probably Im using it in a wrong way.

//CLASS_DEF[./IDENT[ends-with(@text, 'Tests')]]/MODIFIERS/count(ANNOTATION/IDENT[@text='Epic'])=1

[nrmancuso]

Please share a code sample with a case that should match and some others that should not.

[MrStille]

OK class
`@Epic("someLable")
public class lessonsTests {

}`

Error should be shown
`public class forkTests{

}'

[rnveach]

The example query gave me an exception in Checkstyle.

$ cat TestClass.java
@Epic("someLable")
public class lessonsTests {

}
public class forkTests{

}

$ cat TestConfig.xml
<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
          "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
          "https://checkstyle.org/dtds/configuration_1_3.dtd">

<module name="Checker">
    <property name="charset" value="UTF-8"/>
    <property name="severity" value="warning"/>
    <property name="haltOnException" value="false"/>

    <module name="TreeWalker">
 <module name="MatchXpath">
      <property name="query" value="//CLASS_DEF[./IDENT[ends-with(@text, 'Tests')]]/MODIFIERS/count(ANNOTATION/IDENT[@text='Epic'])=1"/>
      <message key="matchxpath.match"
              value="Illegal"/>
 </module>
    </module>
</module>

$ java -jar checkstyle-10.12.3-all.jar -c TestConfig.xml TestClass.java
Starting audit...
[ERROR] TestClass.java:1: Got an exception - java.lang.ClassCastException: class net.sf.saxon.value.BooleanValue cannot be cast to class com.puppycrawl.tools.checkstyle.xpath.AbstractNode (net.sf.saxon.value.BooleanValue and com.puppycrawl.tools.checkstyle.xpath.AbstractNode are in unnamed module of loader 'app')
    at com.puppycrawl.tools.checkstyle.checks.coding.MatchXpathCheck.lambda$findMatchingNodesByXpathQuery$1(MatchXpathCheck.java:157)
    at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
    at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1655)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
    at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
    at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578)
    at com.puppycrawl.tools.checkstyle.checks.coding.MatchXpathCheck.findMatchingNodesByXpathQuery(MatchXpathCheck.java:158)
    at com.puppycrawl.tools.checkstyle.checks.coding.MatchXpathCheck.beginTree(MatchXpathCheck.java:138)
    at com.puppycrawl.tools.checkstyle.TreeWalker.notifyBegin(TreeWalker.java:298)
    at com.puppycrawl.tools.checkstyle.TreeWalker.walk(TreeWalker.java:272)
    at com.puppycrawl.tools.checkstyle.TreeWalker.processFiltered(TreeWalker.java:158)
    at com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck.process(AbstractFileSetCheck.java:101)
    at com.puppycrawl.tools.checkstyle.Checker.processFile(Checker.java:337)
    at com.puppycrawl.tools.checkstyle.Checker.processFiles(Checker.java:296)
    at com.puppycrawl.tools.checkstyle.Checker.process(Checker.java:226)
    at com.puppycrawl.tools.checkstyle.Main.runCheckstyle(Main.java:415)
    at com.puppycrawl.tools.checkstyle.Main.runCli(Main.java:338)
    at com.puppycrawl.tools.checkstyle.Main.execute(Main.java:195)
    at com.puppycrawl.tools.checkstyle.Main.main(Main.java:130)
[Checker]
Audit done.
Checkstyle ends with 1 errors.

[MrStille]

Im not sure that count can work in MatchXpath check. But I did not find another way.

[MrStille]

Found a solution. It was my mistake
working code is
//CLASS_DEF[./IDENT[ends-with(@text, 'Tests')]]/MODIFIERS[count(ANNOTATION/IDENT[@text='Epic'])=0