Writing Tests for a Kafka Consumer

Clone the starter project from GitHub:

cd ~/
git clone https://github.com/linuxacademy/content-ccdak-consumer-tests-lab.git

Perform a test run to make sure the code is able to compile and run:

cd content-ccdak-consumer-tests-lab
./gradlew test

The code should compile, but the tests should fail since they are not implemented yet.

Edit the test class for MemberSignupsConsumer:

vi src/test/java/com/linuxacademy/ccdak/consumer/MemberSignupsConsumerTest.java

Implement the testHandleRecords_output test:

@Test
public void testHandleRecords_output() {
    // Verify that the testHandleRecords writes the correct data to System.out
    // A text fixture called systemOutContent has already been set up in this class to capture System.out data.
    String topic = "member_signups";
    ConsumerRecord<Integer, String> record = new ConsumerRecord<>(topic, 0, 1, 2, "ROSENBERG, WILLOW");
    Map<TopicPartition, List<ConsumerRecord<Integer, String>>> records = new LinkedHashMap<>();
    records.put(new TopicPartition(topic, 0), Arrays.asList(record));
    ConsumerRecords<Integer, String> consumerRecords = new ConsumerRecords<>(records);

    memberSignupsConsumer.handleRecords(consumerRecords);
    Assert.assertEquals("key=2, value=ROSENBERG, WILLOW, topic=member_signups, partition=0, offset=1\n", systemOutContent.toString());
}

Implement the testHandleRecords_none test:

@Test
public void testHandleRecords_none() {
    // Verify that testHandleRecords behaves correctly when processing no records.
    // A text fixture called systemOutContent has already been set up in this class to capture System.out data.
    String topic = "member_signups";
    Map<TopicPartition, List<ConsumerRecord<Integer, String>>> records = new LinkedHashMap<>();
    records.put(new TopicPartition(topic, 0), Arrays.asList());
    ConsumerRecords<Integer, String> consumerRecords = new ConsumerRecords<>(records);

    memberSignupsConsumer.handleRecords(consumerRecords);
    Assert.assertEquals("", systemOutContent.toString());
}

Implement the testHandleRecords_multiple test:

@Test
public void testHandleRecords_multiple() {
    // Verify that testHandleRecords behaves correctly when processing multiple records.
    // A text fixture called systemOutContent has already been set up in this class to capture System.out data.
    String topic = "member_signups";
    ConsumerRecord<Integer, String> record1 = new ConsumerRecord<>(topic, 0, 1, 2, "ROSENBERG, WILLOW");
    ConsumerRecord<Integer, String> record2 = new ConsumerRecord<>(topic, 3, 4, 5, "HARRIS, ALEXANDER");
    Map<TopicPartition, List<ConsumerRecord<Integer, String>>> records = new LinkedHashMap<>();
    records.put(new TopicPartition(topic, 0), Arrays.asList(record1, record2));
    ConsumerRecords<Integer, String> consumerRecords = new ConsumerRecords<>(records);

    memberSignupsConsumer.handleRecords(consumerRecords);
    Assert.assertEquals("key=2, value=ROSENBERG, WILLOW, topic=member_signups, partition=0, offset=1\nkey=5, value=HARRIS, ALEXANDER, topic=member_signups, partition=3, offset=4\n", systemOutContent.toString());
}

Run your tests and make sure they pass:

./gradlew test