Apache Kafka - Real-time Stream Processing (Master Class) - How to test a Stream Processing Application

The video tutorial covers the essentials of unit testing Kafka streams applications, focusing on testing the stream topology. It discusses the challenges of testing with a Kafka cluster and introduces two approaches: using an embedded Kafka cluster for integration testing and the Topology Test Driver for unit testing. An example of calculating the clickthrough rate for an advertisement campaign is provided, demonstrating the process of refactoring code for better testability and defining test cases to validate the application's functionality.

Why is it crucial to test the stream topology in a Kafka streams application?

• To validate the user interface design

• To verify the flow of data through the topology

• To ensure the application compiles without errors

• To check the syntax of the code

What is a major drawback of using an embedded Kafka cluster for testing?

• It requires a lot of manual observation

• It is too lightweight for integration testing

• It does not support automated testing

• It is code heavy and complicated

What tool is recommended for lightweight unit testing of Kafka streams topology?

• Embedded Kafka Cluster

• Kafka Streams API

• Topology Test Driver

• Kafka Console Producer

In the example application, what is the purpose of the left join operation?

• To duplicate the data for redundancy

• To sort the data in ascending order

• To combine counts from ad impressions and clicks

• To filter out unwanted data

What is the first step in creating a Kafka streams topology?

• Create a state store

• Define the business logic

• Instantiate a stream builder object

• Add processors to the stream builder

Which test case validates the correct storage of state in the example application?

• State store representation

• Impression count functionality

• Ad impression flow validation

• Click count functionality

What is the purpose of the test case that sends one ad impression?

• To test the topology creation

• To verify the ad impression flow

• To check the state store

• To validate the click count