Experiencing Code Coverage issue only when using Stream

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I have the following 2 logics and both produces same result tested against same test but the one that is implemented with a Streams produces code coverage issue with 80% and the one using for loop has no code coverage issue. Could I get some advice on why this is the case? Thanks.

This has no code coverage issues

public static Map<String, String> myMethod(List<KafkaHeader> headers) {

    Map<String, String> map = new HashMap<>();

    for(KafkaHeader header : headers) {
        map.put(header.key(), String.valueOf(header.value()));
    }
    return map;
}

When using Stream as follows, there is coverage issue.

public static Map<String, String> myMethod(List<KafkaHeader> headers) {
    return headers.stream()
        .collect(Collectors.toMap(KafkaHeader::key, kafkaHeader -> String.valueOf(kafkaHeader.value())));
}

Test case:

@Test
public void simpleTest() {

    List<KafkaHeader> headers = new ArrayList<>();

    for (int i = 0; i < 10; i++) {
        headers.add(new KafkaHeader("key"+i, "value"+i));
    }

    Map<String, String> headerMap = myclass.myMethod(headers);

    for (int i = 0; i < 10; i++) {
        assertEquals(headerMap.get("key"+i), "value"+i);
    }
}

Note: KafkaHeader is an external class.

java-8 java
1 Answers

As attached screenshot of of method1 and method2, it's showing coverage of 100% with both approach.enter image description here .

enter image description here

Here i am using JUnit4ClassRunner and JACOCO for coverage .

It's working fine for me.

    @RunWith(JUnit4ClassRunner.class)
    public class SampleTest {
    @Test
    public void sample() {
     SampleJava.myMethod(List.of(KafkaHeader.builder().key("key").value("val").build()));
        SampleJava.myMethod1(List.of(KafkaHeader.builder().key("key").value("val").build()));
    }
}
user_58097200
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