模拟具有静态枚举类的类时出现“无法转换具有名称的类”错误

Question

java.lang.IllegalStateException: Failed to transform class with name com.XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX$ReadSets. Reason: null
    at org.powermock.core.classloader.MockClassLoader.loadMockClass(MockClassLoader.java:219)
    at org.powermock.core.classloader.MockClassLoader.loadModifiedClass(MockClassLoader.java:147)
    at org.powermock.core.classloader.DeferSupportingClassLoader.loadClass(DeferSupportingClassLoader.java:67)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at sun.reflect.generics.factory.CoreReflectionFactory.makeNamedType(CoreReflectionFactory.java:114)
    at sun.reflect.generics.visitor.Reifier.visitClassTypeSignature(Reifier.java:125)
    at sun.reflect.generics.tree.ClassTypeSignature.accept(ClassTypeSignature.java:49)
    at sun.reflect.annotation.AnnotationParser.parseSig(AnnotationParser.java:390)
    at sun.reflect.annotation.AnnotationParser.parseClassValue(AnnotationParser.java:371)
    at sun.reflect.annotation.AnnotationParser.parseClassArray(AnnotationParser.java:673)
    at sun.reflect.annotation.AnnotationParser.parseArray(AnnotationParser.java:480)
    at sun.reflect.annotation.AnnotationParser.parseMemberValue(AnnotationParser.java:306)
    at sun.reflect.annotation.AnnotationParser.parseAnnotation(AnnotationParser.java:241)
    at sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:88)
    at sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:70)
    at java.lang.Class.initAnnotationsIfNecessary(Class.java:3089)
    at java.lang.Class.getAnnotations(Class.java:3069)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.classAnnotations(PowerMockJUnit44RunnerDelegateImpl.java:163)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.getDescription(PowerMockJUnit44RunnerDelegateImpl.java:155)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.getDescription(JUnit4TestSuiteChunkerImpl.java:171)
    at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.getDescription(AbstractCommonPowerMockRunner.java:47)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestClassReference.sendTree(JUnit4TestClassReference.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.sendTrees(RemoteTestRunner.java:476)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:464)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.NullPointerException
    at javassist.compiler.MemberResolver.lookupMethod(MemberResolver.java:110)
    at javassist.compiler.MemberResolver.lookupMethod(MemberResolver.java:96)
    at javassist.compiler.TypeChecker.atMethodCallCore(TypeChecker.java:704)
    at javassist.compiler.TypeChecker.atCallExpr(TypeChecker.java:681)
    at javassist.compiler.JvstTypeChecker.atCallExpr(JvstTypeChecker.java:156)
    at javassist.compiler.ast.CallExpr.accept(CallExpr.java:45)
    at javassist.compiler.Javac$1.setReturnType(Javac.java:449)
    at javassist.compiler.JvstTypeChecker.atCallExpr(JvstTypeChecker.java:146)
    at javassist.compiler.ast.CallExpr.accept(CallExpr.java:45)
    at javassist.compiler.TypeChecker.atVariableAssign(TypeChecker.java:248)
    at javassist.compiler.TypeChecker.atAssignExpr(TypeChecker.java:217)
    at javassist.compiler.ast.AssignExpr.accept(AssignExpr.java:38)
    at javassist.compiler.CodeGen.doTypeCheck(CodeGen.java:235)
    at javassist.compiler.CodeGen.atStmnt(CodeGen.java:323)
    at javassist.compiler.ast.Stmnt.accept(Stmnt.java:49)
    at javassist.compiler.CodeGen.atStmnt(CodeGen.java:344)
    at javassist.compiler.ast.Stmnt.accept(Stmnt.java:49)
    at javassist.compiler.CodeGen.atIfStmnt(CodeGen.java:384)
    at javassist.compiler.CodeGen.atStmnt(CodeGen.java:348)
    at javassist.compiler.ast.Stmnt.accept(Stmnt.java:49)
    at javassist.compiler.CodeGen.atStmnt(CodeGen.java:344)
    at javassist.compiler.ast.Stmnt.accept(Stmnt.java:49)
    at javassist.compiler.Javac.compileStmnt(Javac.java:558)
    at javassist.expr.MethodCall.replace(MethodCall.java:233)
    at org.powermock.core.transformers.impl.MainMockTransformer$PowerMockExpressionEditor.edit(MainMockTransformer.java:299)
    at javassist.expr.ExprEditor.loopBody(ExprEditor.java:178)
    at javassist.expr.ExprEditor.doit(ExprEditor.java:90)
    at javassist.CtClassType.instrument(CtClassType.java:1224)
    at org.powermock.core.transformers.impl.MainMockTransformer.transform(MainMockTransformer.java:75)
    at org.powermock.core.classloader.MockClassLoader.loadMockClass(MockClassLoader.java:215)
    ... 28 more

这个类包含一个静态方法getInstance（我想模拟它），以提供一个singleton对象和几个声明为公共静态的枚举类（在异常中可以看到其中一个名为ReadSets的类）。下面是这个类的样子。

有没有关于如何修复的线索？

public class XXX extends YYY {

    private volatile static XXX s_instance;

    public static XXX getInstance() {
        if (s_instance == null)
            synchronized (XXX.class) {
                if (s_instance == null)
                    s_instance = new XXX();
            }
        return s_instance;
    }

    public static enum ReadSets {
        ANY(1), ALL(2);
        int val;

        public int getVal() {
            return val;
        }

        private ReadSets(int v) {
            val = v;
        }
    }

    public static enum UpdateSets {
        ANY(1), ALL(2);
        int val;

        private UpdateSets(int v) {
            val = v;
        }
    }

    // [...]

}

Answer 1

我在一次测试中遇到了同样的问题，对我来说，这是由冲突的Javassist版本引起的。一些依赖项使用javassist.javassist-3.4.ga，而PowerMock使用org.javassist.javassist-3.18.1-ga（org.是主要区别）。似乎是eclipse先将前一个放入类路径中，因此使用了较旧的版本。

我使用maven，因此我可以通过在拉动javassist.javassist的依赖项中创建一个排除规则来解决冲突，并直接依赖于较新的jassist版本。这不是最好的解决方法，但我不知道在Maven中处理这些人工操作的更好方法。

<dependency>
  <groupId>some</groupId>
  <artifactId>dependency</artifactId>
  <version>1.0</version>
  <exclusions>
    <exclusion>
      <groupId>javassist</groupId>
      <artifactId>javassist</artifactId>
    </exclusion>
  </exclusions>
</dependency>
<dependency>
  <groupId>org.javassist</groupId>
  <artifactId>javassist</artifactId>
  <version>3.18.2-GA</version>
</dependency>

当然，您必须检查依赖关系是否仍然适用于该版本。