delta-io/delta

[Kernel][Testing] Add more thorough testing for DataType.toJson

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#2,313 opened on Nov 20, 2023

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 (5 comments) (0 reactions) (0 assignees)Scala (8,807 stars) (2,100 forks)batch import
enhancementgood first issuekernel

Description

Feature request

Which Delta project/connector is this regarding?

  • Spark
  • Standalone
  • Flink
  • Kernel
  • Other (fill in here)

Overview

All of our DataType classes provide toJson which serializes the type following the delta protocol schema serialization rules https://github.com/delta-io/delta/blob/master/PROTOCOL.md#schema-serialization-format. We use this method to serialize the physical and logical schemas in ScanStateRow.

toJson is only tested by the 2 round-trip tests in DefaultJsonHandlerSuite. We should add more thorough tests for toJson.

Contributor guide

Tech stack
None
Domain
testing
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Scala or Java programmingDelta protocol schema serializationExisting test suite structure
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
Start by examining the existing `DefaultJsonHandlerSuite` to understand the current round trip tests for `toJson`. Then identify all `DataType` subclasses and ensure each has a test case that verifies the serialization matches the Delta protocol schema serialization format. Pay attention to edge cases like nested types. Refer to the protocol specification at https://github.com/delta io/delta/blob/master/PROTOCOL.md#schema serialization format for exact rules.