chore: import upstream snapshot with attribution

tests/picker_ui_snap.lua

@@ -0,0 +1,242 @@
+--- End-to-end snapshot tests for fff.nvim's picker UI.
+local MiniTest = require('mini.test')
+local fixture_lib = require('tests.snapshot.fixture')
+
+local PLUGIN_DIR = vim.fn.fnamemodify(debug.getinfo(1, 'S').source:sub(2), ':p:h:h')
+local FORCE = vim.env.UPDATE_SNAPSHOTS == '1'
+
+local child, fixture
+
+local function setup(geometry, opts)
+  opts = opts or {}
+  fixture = fixture_lib.create()
+  child = MiniTest.new_child_neovim()
+  child.start({
+    '--clean',
+    '-n',
+    '-i',
+    'NONE',
+    '--cmd',
+    string.format('let &lines = %d', geometry.rows),
+    '--cmd',
+    string.format('let &columns = %d', geometry.cols),
+  }, {
+    connection_timeout = 15000,
+  })
+
+  child.o.lines = geometry.rows
+  child.o.columns = geometry.cols
+
+  local debug_enabled = opts.debug == true
+  -- Default show_file_info hides timings: Modified/Accessed timestamps drift
+  -- between runs and would otherwise force `ignore_text` on those rows. Tests
+  -- can override (or restore) by passing `opts.show_file_info`.
+  local show_file_info = opts.show_file_info
+    or { file_info = true, score_breakdown = true, timings = false, full_path = true }
+
+  child.lua(
+    string.format(
+      [[
+        local plugin = %q
+        vim.opt.runtimepath:prepend(plugin)
+        package.path = plugin .. '/lua/?.lua;' .. plugin .. '/lua/?/init.lua;' .. package.path
+        vim.cmd('cd ' .. vim.fn.fnameescape(%q))
+        vim.cmd('syntax off')
+        local winborder = %q
+        if winborder ~= '' then vim.o.winborder = winborder end
+        vim.g.fff = {
+          prompt = '> ',
+          frecency = { enabled = true, db_path = %q },
+          history  = { enabled = true, db_path = %q },
+          logging  = { enabled = false },
+          debug    = {
+            enabled = %s,
+            show_scores = %s,
+            show_file_info = %s,
+          },
+        }
+        require('fff.core').ensure_initialized()
+        require('fff.rust').wait_for_initial_scan(8000)
+      ]],
+      PLUGIN_DIR,
+      fixture.root,
+      geometry.winborder or '',
+      fixture.frecency_db,
+      fixture.history_db,
+      tostring(debug_enabled),
+      tostring(debug_enabled),
+      vim.inspect(show_file_info)
+    )
+  )
+end
+
+local function teardown()
+  if child and child.is_running() then pcall(child.stop) end
+  if fixture then fixture_lib.cleanup(fixture) end
+  child, fixture = nil, nil
+end
+
+--- @param opts table|nil { ignore_text?: number[] }
+local function assert_snapshot_match(opts)
+  opts = opts or {}
+  MiniTest.expect.reference_screenshot(child.get_screenshot(), nil, {
+    force = FORCE,
+    ignore_text = opts.ignore_text or false,
+  })
+end
+
+local function open_picker(prompt_position, query)
+  child.lua(
+    string.format('require("fff.picker_ui.picker_ui").open({ layout = { prompt_position = %q } })', prompt_position)
+  )
+  vim.loop.sleep(400)
+
+  if query and query ~= '' then
+    child.type_keys(query)
+    vim.loop.sleep(400)
+  end
+end
+
+local LAYOUTS = {
+  { name = 'wide', cols = 180, rows = 40, winborder = 'double' },
+  { name = 'default', cols = 140, rows = 32 }, -- standard on most screens
+  { name = 'narrow', cols = 70, rows = 24, winborder = 'rounded' },
+  -- Extra-wide: exists primarily so the file_info panel hits the H2 layout.
+  { name = 'xwide', cols = 240, rows = 48 },
+}
+
+local T = MiniTest.new_set()
+
+local PROMPT_POSITIONS = { 'bottom', 'top' }
+
+for _, geometry in ipairs(LAYOUTS) do
+  local set = MiniTest.new_set({
+    hooks = {
+      pre_case = function() setup(geometry) end,
+      post_case = teardown,
+    },
+  })
+
+  -- Run every per-geometry case for both prompt positions: layout math and
+  -- list rendering diverge between top/bottom (see AGENTS.md), so a snapshot
+  -- on a single side would silently miss regressions in the other.
+  for _, prompt in ipairs(PROMPT_POSITIONS) do
+    set['empty_' .. prompt] = function()
+      open_picker(prompt)
+      assert_snapshot_match()
+    end
+
+    set['query_main_' .. prompt] = function()
+      open_picker(prompt, 'main')
+      assert_snapshot_match()
+    end
+
+    set['no_results_' .. prompt] = function()
+      open_picker(prompt, 'zzzzzzzzz')
+      assert_snapshot_match()
+    end
+
+    set['cursor_second_item_' .. prompt] = function()
+      open_picker(prompt)
+      -- Bottom prompt visually goes up with <Down>; top prompt goes down with <Down>.
+      -- Either way one keypress moves to the second item — what we want to capture.
+      child.type_keys('<Down>')
+      vim.loop.sleep(200)
+      assert_snapshot_match()
+    end
+  end
+
+  T[geometry.name] = set
+end
+
+-- File info panel snapshots. Timings are disabled at the config level (see
+-- `setup`) so the snapshots stay deterministic — Modified/Accessed timestamps
+-- drift between runs. We snapshot a narrow and a wide variant for both prompt
+-- positions to keep the adaptive panel layout (label widths, section headers,
+-- top vs bottom prompt geometry) covered.
+local debug_narrow_set = MiniTest.new_set({
+  hooks = {
+    pre_case = function() setup(LAYOUTS[2], { debug = true }) end, -- default 140x32, panel ~57 cols
+    post_case = teardown,
+  },
+})
+
+for _, prompt in ipairs(PROMPT_POSITIONS) do
+  debug_narrow_set['file_info_panel_' .. prompt] = function()
+    open_picker(prompt, 'main')
+    assert_snapshot_match()
+  end
+end
+T['debug_narrow'] = debug_narrow_set
+
+local debug_wide_set = MiniTest.new_set({
+  hooks = {
+    pre_case = function() setup(LAYOUTS[4], { debug = true }) end, -- xwide 240x48, panel ~96 cols
+    post_case = teardown,
+  },
+})
+
+for _, prompt in ipairs(PROMPT_POSITIONS) do
+  debug_wide_set['file_info_panel_' .. prompt] = function()
+    open_picker(prompt, 'main')
+    assert_snapshot_match()
+  end
+end
+T['debug_wide'] = debug_wide_set
+
+T['combo'] = MiniTest.new_set({
+  hooks = {
+    pre_case = function() setup({ cols = 140, rows = 32 }) end,
+    post_case = teardown,
+  },
+})
+
+local function train_combo()
+  -- Train: "main" → src/main.rs four times so open_count crosses the default
+  -- min_combo_count (3). track_query_completion is async; pause between calls
+  -- + final settle for the lmdb writer.
+  for _ = 1, 4 do
+    child.lua(
+      string.format('require("fff.rust").track_query_completion(%q, %q)', 'main', fixture.root .. '/src/main.rs')
+    )
+    vim.loop.sleep(120)
+  end
+  vim.loop.sleep(400)
+end
+
+for _, prompt in ipairs(PROMPT_POSITIONS) do
+  T['combo']['boost_' .. prompt] = function()
+    train_combo()
+    open_picker(prompt, 'main')
+    -- Combo overlay float renders asynchronously after render_list.
+    vim.loop.sleep(400)
+    assert_snapshot_match()
+  end
+end
+
+T['scrollbar'] = MiniTest.new_set({
+  hooks = {
+    pre_case = function() setup({ cols = 140, rows = 32 }) end,
+    post_case = teardown,
+  },
+})
+
+-- Cursor advance key differs by prompt position: bottom prompt iterates the
+-- list in reverse so `<Up>` walks toward higher indices; top prompt is
+-- conventional. Either way we walk past the last in-page item to trigger
+-- load_next_page and surface the scrollbar thumb at the new offset.
+local SCROLL_KEY = { bottom = '<Up>', top = '<Down>' }
+
+for _, prompt in ipairs(PROMPT_POSITIONS) do
+  T['scrollbar']['next_page_' .. prompt] = function()
+    open_picker(prompt)
+    for _ = 1, 30 do
+      child.type_keys(SCROLL_KEY[prompt])
+      vim.loop.sleep(20)
+    end
+    vim.loop.sleep(400)
+    assert_snapshot_match()
+  end
+end
+
+return T