test: add functional tests for config, git adapter, views, keymaps, and bug fixes

[dlyongemallo]

No description provided.

[Copilot]

Pull request overview

Adds a broad set of functional/regression tests across Diffview’s config, actions, adapters, and UI components, plus a small documentation clarification in TIPS.md. This fits the codebase’s existing Plenary/Busted functional test suite by expanding coverage for previously-fixed bugs and newly-added features.

Changes:

• Add multiple new functional specs covering config options/features, actions (layout cycling, restore, open-in-new-tab), adapter behaviors, rendering, keymap save/restore, debounce, and various historical bug fixes.
• Extend existing window and git adapter functional specs with additional regression cases.
• Clarify a leader-key/keymap conflict tip in TIPS.md.

Reviewed changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
TIPS.md	Clarifies how <space> in the file panel can intercept <leader> sequences due to buffer-local keymaps.
lua/diffview/tests/functional/window_spec.lua	Adds tests ensuring _save_winopts handles global-only options safely.
lua/diffview/tests/functional/toggle_spec.lua	Adds functional coverage for diffview.toggle() open/close behavior and arg passthrough.
lua/diffview/tests/functional/panel_render_spec.lua	Adds coverage for file panel rendering (folder counts, loading indicator, “clean” messaging) and collapsed-state preservation.
lua/diffview/tests/functional/node_spec.lua	Adds comparator tests for file tree node sorting, including custom sort_file.
lua/diffview/tests/functional/misc_fixes_spec.lua	Adds regression tests for several historical fixes (oop super call, hg/git guards, config validation, hl style, etc.).
lua/diffview/tests/functional/merge_artifacts_spec.lua	Adds tests for merge artifact detection/filtering behavior.
lua/diffview/tests/functional/keymap_save_spec.lua	Adds tests for buffer-local keymap save/restore during File:attach_buffer() / :detach_buffer().
lua/diffview/tests/functional/git_adapter_spec.lua	Extends git adapter tests (show/log args, untracked logic, merge-base behavior) and job env expectations.
lua/diffview/tests/functional/fold_limit_spec.lua	Adds regression tests ensuring custom fold logic remains removed.
lua/diffview/tests/functional/file_history_render_spec.lua	Adds tests for file history rendering logic (stats bars, dates, entry cycling).
lua/diffview/tests/functional/debounce_spec.lua	Adds tests for debounce/throttle/timeout/interval utilities in async context.
lua/diffview/tests/functional/cycle_layouts_spec.lua	Adds tests for cycle layout defaults, name resolution, and cycling behavior with/without custom config.
lua/diffview/tests/functional/config_options_spec.lua	Adds coverage for specific config defaults and setup persistence (always_show_sections, auto_close_on_empty, etc.).
lua/diffview/tests/functional/config_features_spec.lua	Adds tests for additional config-driven features and validations (clean_up_buffers, rename_threshold, commit_format, etc.).
lua/diffview/tests/functional/closing_guard_spec.lua	Adds regression tests for cancellation/guard logic when views are closing during async updates.
lua/diffview/tests/functional/browser_and_restore_spec.lua	Adds tests for commit URL generation, platform browser command selection, open-in-new-tab, and directory restore behaviors.
lua/diffview/tests/functional/actions_features_spec.lua	Adds action-focused regression tests (set_layout, copy_hash register, scrollbind cleanup, inlay hints).

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