WebSocket连接失败：Karate测试中GraalVM异常求助

问题现象 #

运行Karate WebSocket测试时，持续触发GraalVM PolyglotException，错误信息如下：

Cannot invoke "org.graalvm.polyglot.SourceSection.getCharacters()" because the return value of "org.graalvm.polyglot.Value.getSourceLocation()" is null

错误栈 #

org.graalvm.polyglot.PolyglotException: Cannot invoke "org.graalvm.polyglot.SourceSection.getCharacters()" because the return value of "org.graalvm.polyglot.Value.getSourceLocation()" is null
 - com.intuit.karate.graal.JsFunction$Executable.<init>(JsFunction.java:95)
 - com.intuit.karate.graal.JsFunction$Executable.<init>(JsFunction.java:89)
 - com.intuit.karate.graal.JsFunction$Instantiable.<init>(JsFunction.java:132)
 - com.intuit.karate.graal.JsLambda.<init>(JsLambda.java:37)
 - com.intuit.karate.core.ScenarioBridge.webSocket(ScenarioBridge.java:1110)
 - com.intuit.karate.core.ScenarioBridge.webSocket(ScenarioBridge.java:1101)
 - <js>.:program(Unnamed:1)

测试代码示例 #

Scenario: Account registration and retrieval
    * def handler = function(msg){ return msg.startsWith('{'); }
    * def socket = karate.webSocket('ws://wallet-accountant-karate:8080/ws', handler)

    Given path "http://wallet-accountant-karate:8080/account"
    And request
    """
    {
      bankName: 'a bank',
      name: 'my account',
      accountType: 'checking',
      startingBalance: 123.45,
      startingBalanceDate: '2023-08-26T00:00:00Z',
      currency: 'EUR'
    }
    """
    When method post
    Then status 201
    And match response == {accountId: '#uuid'}
    * listen 1000
    * json result = listenResult
    * match result == { subject: 'account', event: 'accountRegistered' }

解决方案 #

• 升级Karate版本：该问题是Karate与GraalVM交互的已知bug，在Karate 1.4.0及后续稳定版本中已修复，直接升级到最新版即可解决。
• 调整Handler定义格式：将单行匿名函数改为多行字符串包裹的函数定义，避免GraalVM无法识别源代码位置：

  * def handler = """
    function(msg) {
      return msg.startsWith('{');
    }
    """
  

• 校验GraalVM版本兼容性：确保使用的GraalVM版本为22.3或更高，与当前Karate版本匹配，避免版本不兼容导致的异常。

内容的提问来源于stack exchange，提问作者mumia