Calling get on base class after building subclass instance does not work

[piotrgajow]

Having two domain classes, when one extends the other using tablePerHierarchy mechanism produces strange results when building test data.

How to reproduce:

1. Create base domain class Base
2. Create domain class Subclass extending Base
3. Inside test build instance of Subclass def instance = Subclass.build()
4. Running Base.get(instance.id) results in null whereas it should return instance object

Workaround:

Running Base.list() or Subclass.list() before the get fixes the issue.

GitHub with reproduction:

https://github.com/piotrgajow/Sandbox/tree/grails-BuildTestDataPlugin-InheritanceIssue

All of tests from this specification pass.

Environment:

Plugin: 3.0.1
OS: Windows 10
Gradle: 3.4.1
Grails: 3.2.8
Groovy: 2.4.7
JVM: 1.8.0_131

[piotrgajow]

I have also found out, that calling load or findById methods do work.