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Writing Tests for a Kafka Streams Application

Kafka Streams applications provide powerful tools for data processing, but the need to run them against a real Kafka cluster in order to exercise and test your code may be frustrating. Luckily, Kafka provides a collection of test utilities that can make the process of testing your code easier. These utilities can even allow you to unit test your streams topologies. In this lab, we will work hands-on with these test utilities by building unit tests for an existing Kafka Streams application.

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Path Info

Level

Intermediate

Duration

45m

Published

Oct 18, 2019

Challenge

Clone the Starter Project from GitHub and Perform a Test Run
1. Clone the starter project from GitHub:
```
cd ~/
git clone https://github.com/linuxacademy/content-ccdak-streams-tests-lab.git
```
2. Perform a test run to make sure the code is able to compile and run:
```
cd content-ccdak-streams-tests-lab
./gradlew test
```
  The code should compile, but the tests should fail since they are not implemented yet.

Challenge

Implement the Unit Tests for the `MemberSignupsStream`

Edit the test class for MemberSignupsStream:

vi src/test/java/com/linuxacademy/ccdak/streams/MemberSignupsStreamTest.java

Implement the test_first_name test:

@Test
public void test_first_name() {
    // Verify that the stream accurately parses the first name from the value.
    ConsumerRecordFactory<Integer, String> factory = new ConsumerRecordFactory<>("member_signups", new IntegerSerializer(), new StringSerializer());
    ConsumerRecord<byte[], byte[]> record = factory.create("member_signups", 1, "Summers, Buffy");
    testDriver.pipeInput(record);

    ProducerRecord<Integer, String> outputRecord = testDriver.readOutput("member_signups_mail", new IntegerDeserializer(), new StringDeserializer());

    OutputVerifier.compareKeyValue(outputRecord, 1, "Buffy");
}

Implement the test_unknown_name_filter test:

@Test
public void test_unknown_name_filter() {
    // Verify that the stream filters out records with an empty name value.
    ConsumerRecordFactory<Integer, String> factory = new ConsumerRecordFactory<>("member_signups", new IntegerSerializer(), new StringSerializer());
    ConsumerRecord<byte[], byte[]> record = factory.create("member_signups", 1, "UNKNOWN");
    testDriver.pipeInput(record);

    ProducerRecord<Integer, String> outputRecord = testDriver.readOutput("member_signups_mail", new IntegerDeserializer(), new StringDeserializer());

    Assert.assertNull(outputRecord);
}

Implement the test_empty_name_filter test:

@Test
public void test_empty_name_filter() {
    // Verify that the stream filters out records with an empty name value.
    ConsumerRecordFactory<Integer, String> factory = new ConsumerRecordFactory<>("member_signups", new IntegerSerializer(), new StringSerializer());
    ConsumerRecord<byte[], byte[]> record = factory.create("member_signups", 1, "");
    testDriver.pipeInput(record);

    ProducerRecord<Integer, String> outputRecord = testDriver.readOutput("member_signups_mail", new IntegerDeserializer(), new StringDeserializer());

    Assert.assertNull(outputRecord);
}

Run your tests and make sure that they pass:
```
./gradlew test
```

Author

A Cloud Guru

The Cloud Content team comprises subject matter experts hyper focused on services offered by the leading cloud vendors (AWS, GCP, and Azure), as well as cloud-related technologies such as Linux and DevOps. The team is thrilled to share their knowledge to help you build modern tech solutions from the ground up, secure and optimize your environments, and so much more!

What's a lab?

Hands-on Labs are real environments created by industry experts to help you learn. These environments help you gain knowledge and experience, practice without compromising your system, test without risk, destroy without fear, and let you learn from your mistakes. Hands-on Labs: practice your skills before delivering in the real world.