How do you test code that uses collectors?

Testing Java code that utilizes collectors can be accomplished by leveraging JUnit and assertions. This allows you to verify that the collection produced by the collector meets expected outcomes based on the input data. Below is a practical example of how to test code with collectors in a simple Java application.

In this example, we'll use the `Collectors.toList()` method to gather elements into a list, and we will write a unit test to ensure it's functioning as expected.


        import static org.junit.jupiter.api.Assertions.assertEquals;
        import org.junit.jupiter.api.Test;
        import java.util.Arrays;
        import java.util.List;
        import java.util.stream.Collectors;

        public class CollectorTest {
            @Test
            public void testCollectToList() {
                List names = Arrays.asList("Alice", "Bob", "Charlie");
                List result = names.stream()
                                            .filter(name -> name.startsWith("A"))
                                            .collect(Collectors.toList());

                assertEquals(Arrays.asList("Alice"), result);
            }
        }

How do you test code that uses collectors?

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How do you test code that uses collectors?

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