Page Comparison

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1. Implement this second test

2. Code Block
   language java
   @Test public void find_heighest_score_with_array_of_one_return_array_of_one() { // Arrange int[] scores = { 56, 67, 45, 89 }; String topicName = "Physics"; ArrayList<TopicScores> topicScores = new ArrayList<>(); topicScores.add(new TopicScores(topicName, scores)); TopicManager cut = new TopicManager(); ArrayList<TopicTopScore> expectedResult = new ArrayList<>(); expectedResult.add(new TopicTopScore(topicName, 89)); // Act ArrayList<TopicTopScore> result = cut.findTopicHighScores(topicScores); assertEquals(resultexpectedResult.get(0).getTopicName(), expectedResultresult.get(0).getTopicName()); assertEquals(resultexpectedResult.get(0).getTopScore(), expectedResultresult.get(0).getTopScore() ); }

3. And here is the implementation class

4. Code Block
   language c#
   class TopicManager { private final HighestNumberFinder highestNumberFinder = new HighestNumberFinder(); ArrayList<TopicTopScore> findTopicHighScores(ArrayList<TopicScores> array) { ArrayList<TopicTopScore> topScores = new ArrayList<>(); if(array.size() == 1) { TopicScores ts = array.get(0); int topScore = highestNumberFinder.findHighestNumber(ts.getScores()); topScores.add(new TopicTopScore(ts.getTopicName(), topScore)); } return topScores; } }

5. Updated TopicScores.java

6. Code Block
   package com.s2s.demos.topicmanager; public class TopicScores { private String topicName; private int[] scores; public TopicScores(String topicName, int[] scores) { this.topicName = topicName; this.scores = scores; } public String getTopicName() { return topicName; } public int[] getScores() { return scores; } }

7. Updated TopicTopScores.java

8. Code Block
   public class TopicTopScore { private String topicName; private int topScore; public TopicTopScore(String topicName, int score) { this.topScore = score; this.topicName = topicName; } public String getTopicName() { return topicName; } public int getTopScore() { return topScore; } }

9. Looking back at TopicManager, Line 3 represents the elephant in the code

   1. We already have tests for the HighestNumberFinder class, and yes class TopicManager requires HighestNumberFinder. But the coupling between these two classes is such that we cannot test TopicManger independently of HighestNumberFinder. Actually, this is a code smell.

   2. we can not substitute out HighestNumberFinder, this also is a code smell.

   3. We can remove the code smell by injecting HighestNumberFinder into TopicManager, when TopicManager is created.

10. Modify TopicManager as follows

    1. remove the creation of HighestNumberFinder at line 5

    2. Pass an instance of a HighestNumberFinder into TopicManager as a constructor parameter

11. Code Block
    language c#
    public class TopicManager { private HighestNumberFinder highestNumberFinder; public TopicManager( HighestNumberFinder hnf ) { highestNumberFinder = hnf; } public TopicTopScore[] findTopicHighScores(TopicScores[] array) { if(array.Length == 1) { List<TopicTopScore> topScores = new List<TopicTopScore>(); TopicScores ts = array[0]; int topScore = highestNumberFinder.findHighestNumber(ts.Scores); topScores.Add(new TopicTopScore(ts.TopicName, topScore)); return topScores.ToArray(); } else return Array.Empty<TopicTopScore>(); } }

12. Refactor the tests so that they run. You should not have to change any of the test data.

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   @Test
   public void find_heighest_score_with_array_of_one_return_array_of_one_using_stub()
   {
       // Arrange
       int[] scores = { 56, 67, 45, 89 };
       String topicName = "Physics";
       ArrayList<TopicScores> topicScores = new ArrayList<>();
       topicScores.add(new TopicScores(topicName, scores));
   
       // Use a stub version of HighestNumberFinder
       com.s2s.demos.topicmanager.HighestNumberFinder hnf = 
                        new com.s2s.demos.topicmanager.HighestNumberFinder();
       TopicManager cut = new TopicManager(hnf);
       ArrayList<TopicTopScore> expectedResult = new ArrayList<>();
       expectedResult.add(new TopicTopScore(topicName, 89));

       // Act
       ArrayList<TopicTopScore> result = cut.findTopicHighScores(topicScores);

       
       assertEquals(resultexpectedResult.get(0).getTopicName(), expectedResultresult.get(0).getTopicName());
       assertEquals(resultexpectedResult.get(0).getTopScore(), expectedResultresult.get(0).getTopScore() );
   }

There will be a number of errors in the code, we will eliminate them one by one

Here is the Stub you will use (create it in the test folder - it’s not production code)

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Now let’s substitute a stub in place of the real implementation of HighestNumberFinder.

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Create a new called find_heighest_score_with_array_of_one_return_array_of_one_using_stub(), it's a copy of find_heighest_score_with_array_of_one_return_array_of_one()

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        [Test]
        public void find_heighest_score_with_array_of_one_return_array_of_one_using_stub()
        {
            // Arrange
            int[] scores = { 56, 67, 45, 89 };
            string topicName = "Physics";
            TopicScores[] topicScores = { new TopicScores(topicName, scores) };
            IHighestNumberFinder hnf = new FindHighestNumberServiceFinal.HighestNumberFinder();
            TopicManager cut = new TopicManager(hnf);
            TopicTopScore[] expectedResult = { new TopicTopScore(topicName, 89) };

            // Act
            TopicTopScore[] result = cut.findTopicHighScores(topicScores);

            // Assert
            Assert.AreEqual(result[0].TopicName, expectedResult[0].TopicName);
            Assert.AreEqual(result[0].TopScore, expectedResult[0].TopScore);
        }
    }

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Modify line 8 to

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    IHighestNumberFinder hnf = new TopicManagerService.HighestNumberFinder();

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The error is because of TopicManagerTests.HighestNumberFinder does not implement the IHighestNumberFinder interface. Modify it so that it does.

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