[Solved] Given this code snippet using TopologyTestDriver to process a... System.out.println(result.key + ":" + result.value);What will be printed if the topology forwards input to output unchanged? | Kafka

Kafka - Advanced Stream Processing

Given this code snippet using TopologyTestDriver to process a record:

var driver = new TopologyTestDriver(topology, props);
var inputTopic = driver.createInputTopic("input", new StringSerializer(), new StringSerializer());
inputTopic.pipeInput("key1", "value1");
var outputTopic = driver.createOutputTopic("output", new StringDeserializer(), new StringDeserializer());
var result = outputTopic.readKeyValue();
System.out.println(result.key + ":" + result.value);

What will be printed if the topology forwards input to output unchanged?

Akey1:value1

Bvalue1:key1

Cnull:null

DException thrown at runtime

Step-by-Step Solution

Solution:

Step 1: Understand the data flow in the test
The input topic receives key "key1" and value "value1"; the topology forwards it unchanged to output topic.
Step 2: Read output and print
Reading from output topic returns the same key-value pair; printing concatenates as "key1:value1".
Final Answer:
key1:value1 -> Option A
Quick Check:
Forwarded key-value output = C [OK]

Quick Trick: Output matches input if topology forwards unchanged [OK]

Common Mistakes:

Swapping key and value in output
Expecting null if no processing
Assuming runtime exceptions without errors

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More Kafka Quizzes

Given this code snippet using TopologyTestDriver to process a record:

Step 1: Understand the data flow in the test

Step 2: Read output and print

Final Answer:

Quick Check:

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