java data_error ai_generated true

java.lang.AssertionError: expected: [1, 2, 3] but was: [1, 2, 4]

ID: java/junit-assertion-expected-actual-mismatch

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80%Fix Rate
82%Confidence
0Evidence
2025-01-20First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
8+ active — — —

Root Cause

Test assertion failed due to mismatch between expected and actual values, often from incorrect test data or logic.

generic

中文

测试断言失败，因为期望值与实际值不匹配，通常由于测试数据或逻辑错误。

Workarounds

  1. 90% success Use assertIterableEquals for lists 
    import static org.junit.jupiter.api.Assertions.assertIterableEquals;
assertIterableEquals(expectedList, actualList);
  2. 85% success Debug by printing actual values 
    System.out.println("Actual: " + actualList);
// Then fix production code

Dead Ends

Common approaches that don't work:

  1. Changing expected value to match actual without investigation 80% fail

    Hides real bug in production code.

  2. Ignoring order in lists without using appropriate matcher 60% fail

    AssertEquals checks order; using it for unordered lists causes false failures.