Drop OpenStruct use from FakeApplicationSettings
What does this MR do?
OpenStruct has been pointed out as problematic to use. Ruby 3 added a good Caveats section to the OpenStruct rdoc explaining why its use is often not a good idea: https://docs.ruby-lang.org/en/3.0.0/OpenStruct.html#class-OpenStruct-label-Caveats
The problem this MR fixes is that the current implementation of FakeApplicationSettings, which is derived from OpenStruct, will actually break under Ruby 3, due to a change that materializes attributes passed through the constructor eagerly rather than lazily, which breaks inheritance contracts (such as the inclusion of module methods that are meant to override ostruct members.)
Context: #336754 (comment 646177087)
Therefore, this patch drops the use of OpenStruct entirely in this class
in favor of some hand-rolled (but simple) meta-programming that mimics
OStruct behavior from 2.7 where relevant.
Does this MR meet the acceptance criteria?
Conformity
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I have included changelog trailers, or none are needed. (Does this MR need a changelog?) -
I have added/updated documentation, or it's not needed. (Is documentation required?) -
I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?) -
I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?) -
I have self-reviewed this MR per code review guidelines. -
This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines) -
I have followed the style guides. -
This change is backwards compatible across updates, or this does not apply.
Availability and Testing
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I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.) -
I have tested this MR in all supported browsers, or it's not needed. -
I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.