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javaunit-testingjunithamcrest

Hamcrest Matcher for no duplicates in a List of Strings?

I would like a simple hamcrest matcher for finding duplicates of an object in a List<String>. This is what I wrote

for (QuizEntity quiz : quizzes)
            for (QuestionEntity question : quiz.getQuestions())
                Assert.assertThat("There should be no duplicate questions", 1, Matchers.equalTo(Collections.frequency(questions, question.getQuestion())));

Unfortunately I got this output, which isn't descriptive enough. Any

java.lang.AssertionError: There should be no duplicate questions
Expected: <20>
     but: was <1>
Solution

  • Replaced 

    Assert.assertThat("There should be no duplicate questions", 1, Matchers.equalTo(Collections.frequency(questions, question.getQuestion())));

    with

    Assert.assertThat("Question '" + question.getQuestion() + "' should not be duplicated", 1, Matchers.equalTo(Collections.frequency(questions, question.getQuestion())));