Importing test data from Control Center

Note: I created a question for this on StackOverflow, but after not getting much response there, thought it may be better here: java - Creating test data from Confluent Control Center JSON representation - Stack Overflow

I am starting out trying to write Streams apps manipulating some records in Avro format.

As I don’t really want to create a lot of complicated objects manually in code, I’d prefer to be able to pick a message out from Control Center, save it to a file and instantiate an object from it in my unit tests.

I’m using SpecificRecords in my tests, and obviously Control Center output is in Avro-flavoured JSON, so I’d like to combine that JSON together with the schema file from ControlCenter to seed my input topic.

What I’ve tried so far is the following, which I attempted to adapt from a GenericRecord example:

            var testAvroString = "{JSON copied from Control Center topic}";
            Schema schema = price_assessment.getClassSchema();
            DecoderFactory decoderFactory = new DecoderFactory();
            Decoder decoder = null;
            try {
                DatumReader<price_assessment> reader = new SpecificDatumReader<price_assessment>();
                decoder = decoderFactory.get().jsonDecoder(schema, testAvroString);
                return, decoder);
            } catch (Exception e)
                return null;

however, running this returns Cannot invoke "org.apache.avro.Schema.equals(Object)" because "writer" is null on the step.

Running on Java 17 / Streams 3.1.0