java config_error ai_generated true

org.mockito.exceptions.base.MockitoException: Cannot instantiate @InjectMocks field named 'service' of type 'class com.example.MyService'

ID: java/mockito-injectmocks-failure

Also available as: JSON · Markdown · 中文
80%Fix Rate
87%Confidence
0Evidence
2024-10-05First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
8+ active — — —

Root Cause

@InjectMocks requires a no-arg constructor or constructor injection, but class lacks one or has ambiguous constructors.

generic

中文

@InjectMocks 需要无参构造函数或构造函数注入，但类缺少无参构造函数或有歧义的构造函数。

Workarounds

  1. 90% success Provide a no-arg constructor in production class 
    public MyService() {
    // default constructor
}
  2. 85% success Use manual construction with mocks 
    MyService service = new MyService(mockDep1, mockDep2);

Dead Ends

Common approaches that don't work:

  1. Adding @InjectMocks to a field with private constructor 70% fail

    Mockito cannot instantiate the class.

  2. Using @Spy on the same field 50% fail

    Spy requires an instance; @InjectMocks is for creating instances.