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unit-test-mapper-converter

Validate MapStruct mapper and converter transformations between domain objects and DTOs.

Updated Apr 5, 2026
Search Tags:#unit-testing#mapper#dto#entity#junit-5#mapstruct#recursive-comparison
One-click install
npx skills add https://github.com/rizaldiem/digital-invitation-web_V2 --skill unit-test-mapper-converter-rizaldiem
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: unit-test-mapper-converter
Source: https://github.com/rizaldiem/digital-invitation-web_V2/tree/main/.windsurf/skills/unit-test-mapper-converter
Command: npx skills add https://github.com/rizaldiem/digital-invitation-web_V2 --skill unit-test-mapper-converter-rizaldiem

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Mapping defects between DTOs and domain models lead to silent data corruption, broken APIs, and integration failures; this Skill provides patterns to isolate and verify mapping logic so transformation bugs are caught early in unit tests.

Core Features & Use Cases

  • Mapping patterns: Concrete unit testing patterns for MapStruct mappers and custom converter classes to verify field mappings and reverse mappings.
  • Null and edge-case validation: Strategies to assert null handling, empty collections, and behavior for missing nested objects.
  • Nested, enum and partial update testing: Methods for recursive comparison of nested structures, enum value translation checks, and verifying @MappingTarget partial updates.
  • Use Case: Validate that a User entity round-trips to UserDto and back while preserving nested Address and Phone objects, ensuring expression-based mappings and discounts are computed correctly.

Quick Start

Run a unit test that uses Mappers.getMapper(UserMapper.class) to assert entity-to-DTO and DTO-to-entity mappings including null handling and nested object correctness.

Frequently Asked Questions about unit-test-mapper-converter

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I unit test MapStruct mappers for nested object mapping accuracy?▼

Validate MapStruct mappers by executing Mappers.getMapper() to assert entity-to-DTO transformations, using recursive comparison to verify nested object mapping accuracy. This catches silent data corruption early in unit tests.

What is the best way to verify bidirectional round-trip fidelity between DTOs and entities?▼

Verify bidirectional round-trip fidelity by mapping a domain entity to a DTO and reversing the process, then asserting the final object matches the original. This includes checking expression-based mappings and ensuring computed values are preserved.

How do I test null-safety and empty collections in Java converter classes?▼

Test null-safety in Java converter classes by asserting null handling, empty collections, and behavior for missing nested objects. This isolates mapping logic to ensure transformation bugs do not cause broken APIs.

Does JUnit 5 support recursive comparison for MapStruct partial updates with @MappingTarget?▼

JUnit 5 supports recursive comparison suitable for verifying MapStruct partial updates using @MappingTarget. This approach validates that only specified fields are updated while nested structures and enum translations remain unchanged.

Why do my DTO-to-entity mappings fail during enum translation and nested object checks?▼

DTO-to-entity mappings fail when unit tests lack recursive comparison for nested structures or miss enum translation checks. Isolate mapper logic and verify field-level accuracy to catch silent data corruption early.

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