Writing Tests for a Kafka Producer

Clone the starter project from GitHub:

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

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

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

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

Edit the test class for MemberSignupsProducer:

vi src/test/java/com/linuxacademy/ccdak/producer/MemberSignupsProducerTest.java

Implement the testHandleMemberSignup_sent_data test:

@Test
public void testHandleMemberSignup_sent_data() {
    // Perform a simple test to verify that the producer sends the correct data to the correct topic when handleMemberSignup is called.
    // Verify that the published record has the memberId as the key and the uppercased name as the value.
    // Verify that the records is sent to the member_signups topic.
    memberSignupsProducer.handleMemberSignup(1, "Summers, Buffy");

    mockProducer.completeNext();

    List<ProducerRecord<Integer, String>> records = mockProducer.history();
    Assert.assertEquals(1, records.size());
    ProducerRecord<Integer, String> record = records.get(0);
    Assert.assertEquals(Integer.valueOf(1), record.key());
    Assert.assertEquals("SUMMERS, BUFFY", record.value());
    Assert.assertEquals("member_signups", record.topic());    
}

Implement the testHandleMemberSignup_partitioning test:

@Test
public void testHandleMemberSignup_partitioning() {
    // Verify that records with a value starting with A-M are assigned to partition 0, and that others are assigned to partition 1.
    // You can send two records in this test, one with a value that begins with A-M and the other that begins with N-Z.
    memberSignupsProducer.handleMemberSignup(1, "M");
    memberSignupsProducer.handleMemberSignup(1, "N");

    mockProducer.completeNext();
    mockProducer.completeNext();

    List<ProducerRecord<Integer, String>> records = mockProducer.history();
    Assert.assertEquals(2, records.size());
    ProducerRecord<Integer, String> record1 = records.get(0);
    Assert.assertEquals(Integer.valueOf(0), record1.partition());
    ProducerRecord<Integer, String> record2 = records.get(1);
    Assert.assertEquals(Integer.valueOf(1), record2.partition());
}

Implement the testHandleMemberSignup_output test:

@Test
public void testHandleMemberSignup_output() {
    // Verify that the producer logs the record data to System.out.
    // A text fixture called systemOutContent has already been set up in this class to capture System.out data.
    memberSignupsProducer.handleMemberSignup(1, "Summers, Buffy");

    mockProducer.completeNext();

    Assert.assertEquals("key=1, value=SUMMERS, BUFFY\n", systemOutContent.toString());
}

Implement the testHandleMemberSignup_error test:

@Test
public void testHandleMemberSignup_error() {
    // Verify that the producer logs the error message to System.err if an error occurs when seding a record.
    // A text fixture called systemErrContent has already been set up in this class to capture System.err data.
    memberSignupsProducer.handleMemberSignup(1, "Summers, Buffy");

    mockProducer.errorNext(new RuntimeException("test error"));

    Assert.assertEquals("test error\n", systemErrContent.toString());
}

Run your tests and make sure they pass:

./gradlew test