Add unit tests for BaseButton and ButtonGroup

[PedroHOCostaa]

Description

This Pull Request attends to issue #43440 implementing unit tests for BaseButton and ButtonGroup classes. These tests were developed using specification testing and then structural testing, using branch coverage and code analysis.

Changes Covered by New Tests

BaseButton Core Interaction & State Machine

• Press/Release Mechanics: Validated is_pressed() conditions and verified correct state behavior across both action modes (ACTION_MODE_BUTTON_PRESS vs ACTION_MODE_BUTTON_RELEASE).
• Toggle System: Tested toggle states under both press and release action modes, ensuring the pressed and toggled signals emit at precise, expected times.
• Silent State Changes: Verified that set_pressed_no_signal() updates the button state cleanly without triggering any signal listeners (and ensures it is ignored when toggle_mode is off).
• Disabled State Guardrails: Ensured disabled buttons still receive mouse hover events but strictly ignore input clicks and suppress signal emissions.
• Draw Mode State Machine: Covered all structural transitions for get_draw_mode() (DRAW_NORMAL, DRAW_HOVER, DRAW_PRESSED, DRAW_HOVER_PRESSED, and DRAW_DISABLED).

Input Gestures & System Notifications

• Touch & Drag Input: Emulated touch workflows (InputEventScreenTouch, InputEventScreenDrag) along with mouse motion events to validate complex pointer interactions under varying keep_pressed_outside conditions.
• Notification Lifecycle: Tested click cancellation mechanisms via standard GUI notifications such as NOTIFICATION_DRAG_BEGIN, NOTIFICATION_SCROLL_BEGIN, and focus loss (NOTIFICATION_FOCUS_EXIT).
• Masks & Shortcuts: Validated custom mouse button masks (MouseButtonMask) and tested automatic trigger responses mapped via Shortcut associations.

ButtonGroup Mechanics & Lifecycle

• Mutual Exclusion: Validated radio-button style exclusion behaviors and the allow_unpress property configuration.
• Exposed Bindings: Added validations for exposed list methods (get_buttons internally and _get_buttons exposed to GDScript).
• Safe Cleanup: Guaranteed that buttons are automatically and safely removed from their assigned ButtonGroup when destroyed in memory.

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Core Files Involved

• tests/scene/test_button.cpp
• tests/scene/test_button.h

Results of the coverage report in base_button.cpp

Branch	Line Coverage percentage	Line Coverage	Branches percentage	Branches
Master branch	42.1 %	182 / 432	17.8 %	56 / 314
This branch	79.5 %	348 / 438	57.5 %	214 / 372

[AThousandShips]

Did you use AI to write any of the code or the PR description? Please see our contribution guidelines and this post

[AThousandShips]

Why this comment?

[PedroHOCostaa]

Two reasons: to separate the following tests from the ButtonGroup tests, and because none of them are actually testing the mechanics of the Button class. All of them refer to the BaseButton class, but since BaseButton is an abstract class, I think it feels 'wrong' to instantiate it directly. Perhaps I could change the code so that the tests are separated by namespace.

[AThousandShips]

I think it's redundant and obvious from the code

[PedroHOCostaa]

ok, will remove it along with other useless comments

[PedroHOCostaa]

Did you use AI to write any of the code or the PR description? Please see our contribution guidelines and this post

I did use it for assistance in some parts, but not an agent like copilot, and I did in fact use it to create that description, it's for a It was for a university project. And the dead line was yesterday, I wanted to have this pull request created before submitting it. I will make it smaller and more precise (y).

[AThousandShips]

and I did in fact use it to create that description, it's for a It was for a university project.

Thank you yes please do rewrite it yourself to make sure it is valid, and disclose how and where you used AI tools and if it generated any code