Testing stream topologies in Kafka - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a stream topology in Kafka Streams?

A stream topology is a directed graph of stream processors and state stores that defines the data processing logic in Kafka Streams.

beginner

Why do we test stream topologies?

Testing stream topologies ensures that the data processing logic works correctly before deploying to production, catching bugs early and verifying transformations.

intermediate

What is the purpose of the TopologyTestDriver in Kafka Streams?

TopologyTestDriver allows you to test your Kafka Streams topology in memory without needing a real Kafka cluster, making tests fast and reliable.

intermediate

How do you feed input data to a topology for testing?

You create input topics using the TopologyTestDriver and pipe input records into them to simulate streaming data for your topology.

intermediate

How can you verify the output of a Kafka Streams topology in tests?

You read output records from output topics created with TopologyTestDriver and assert that the results match expected values.

What does the TopologyTestDriver simulate?

A A web server

B A Kafka cluster for testing stream topologies

C A database connection

D A file system

TopologyTestDriver simulates a Kafka cluster environment to test stream topologies without needing a real Kafka setup.

Which of the following is NOT a benefit of testing stream topologies?

A Deploy faster without any tests

B Catch bugs early

C Verify data transformations

D Run tests without a real Kafka cluster

Deploying without tests is risky and not a benefit of testing; testing helps ensure correctness before deployment.

How do you provide input data to a topology in tests?

A By sending HTTP requests

B By writing to a database

C By creating input topics and piping records into them

D By reading from files

Input topics created with TopologyTestDriver allow you to pipe input records to simulate streaming data.

What do you check to verify the output of a stream topology test?

A Output records from output topics

B Log files

C Database entries

D Network packets

Output records from output topics are read and checked against expected results to verify correctness.

Which Kafka Streams component defines the processing logic?

A Consumer

B Kafka broker

C Producer

D Stream topology

The stream topology defines the processing steps and data flow in Kafka Streams.

Explain how you would test a Kafka Streams topology using TopologyTestDriver.

Think about simulating input and checking output without a real Kafka cluster.

Why is testing stream topologies important before deploying your Kafka Streams application?

Consider the risks of deploying untested streaming logic.