Hamcrest Matcher在字符串列表中沒有重複項？

我想要一個簡單的Hamcrest匹配器，用於查找List<String>中某個對象的重複項。這就是我寫的Hamcrest Matcher在字符串列表中沒有重複項？

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())));

不幸的是我得到這個輸出，這是不夠描述。任何

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

來源

2015-07-21 ZakTaccardi

代替

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

與

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

來源

2015-07-21 16:40:01 ZakTaccardi

另一種選擇是使用hasDistinctElements()匹配從Cirneco library（即在端部是一個Hamcrest擴展名）。

可以使用如下：

Assert.assertThat("There should be no duplicate questions", questions, CirnecoMatchersJ7.hasDistinctElements());

，同時我建議做

import static CirnecoMatchersJ7.*;

，使其更可讀

assertThat("There should be no duplicate questions", questions, hasDistinctElements());

購買cirneco也有一定的流暢表現，即

given(questions).withReason("There should be no duplicate questions").assertThat(hasDistinctElements());

如下的依賴性可以被導入：

<dependency> 
    <groupId>it.ozimov</groupId> 
    <artifactId>java7-hamcrest-matchers</artifactId> 
    <version>0.7.0</version> 
</dependency>

來源

2016-01-04 22:22:22 JeanValjean

Hamcrest Matcher在字符串列表中沒有重複項？

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