fix: replace non-existent Panel:get_winid() with winid field (sindrets#611) (#16)

Author: dlyongemallo

lua/diffview/scene/views/diff/listeners.lua

@@ -23,7 +23,7 @@ return function(view)
 
       -- Restore panel cursor position.
       if view.panel_cursor and view.panel:is_open() then
-        local winid = view.panel:get_winid()
+        local winid = view.panel.winid
         if winid and api.nvim_win_is_valid(winid) then
           pcall(api.nvim_win_set_cursor, winid, view.panel_cursor)
         end
@@ -38,7 +38,7 @@ return function(view)
 
       -- Save panel cursor position.
       if view.panel:is_open() then
-        local winid = view.panel:get_winid()
+        local winid = view.panel.winid
         if winid and api.nvim_win_is_valid(winid) then
           view.panel_cursor = api.nvim_win_get_cursor(winid)
         end

lua/diffview/scene/views/file_history/listeners.lua

@@ -22,7 +22,7 @@ return function(view)
 
       -- Restore panel cursor position.
       if view.panel_cursor and view.panel:is_open() then
-        local winid = view.panel:get_winid()
+        local winid = view.panel.winid
         if winid and api.nvim_win_is_valid(winid) then
           pcall(api.nvim_win_set_cursor, winid, view.panel_cursor)
         end
@@ -33,7 +33,7 @@ return function(view)
 
       -- Save panel cursor position.
       if view.panel:is_open() then
-        local winid = view.panel:get_winid()
+        local winid = view.panel.winid
         if winid and api.nvim_win_is_valid(winid) then
           view.panel_cursor = api.nvim_win_get_cursor(winid)
         end

lua/diffview/tests/functional/panel_spec.lua

@@ -0,0 +1,71 @@
+local helpers = require("diffview.tests.helpers")
+
+local eq = helpers.eq
+
+describe("diffview.ui.panel", function()
+  local Panel = require("diffview.ui.panel").Panel
+
+  describe("interface contract", function()
+    -- The tab_enter/tab_leave listeners in diff and file_history views
+    -- depend on panel instances exposing a `winid` field and an `is_open`
+    -- method.  Verify these exist on the base class so that a future
+    -- refactor cannot silently break the contract (see issue #611).
+
+    it("has a winid field after init", function()
+      local panel = Panel({
+        bufname = "TestPanel",
+        config = Panel.default_config_split,
+      })
+      -- winid starts nil (panel not yet opened).
+      eq(nil, panel.winid)
+    end)
+
+    it("exposes is_open as a callable method", function()
+      local panel = Panel({
+        bufname = "TestPanel",
+        config = Panel.default_config_split,
+      })
+      eq("function", type(panel.is_open))
+    end)
+
+    it("is_open returns falsy when winid is nil", function()
+      local panel = Panel({
+        bufname = "TestPanel",
+        config = Panel.default_config_split,
+      })
+      assert.falsy(panel:is_open())
+    end)
+
+    it("does not expose a get_winid method", function()
+      -- get_winid has never been part of the Panel API.  Callers should
+      -- access the winid field directly.  This test guards against
+      -- accidental re-introduction of calls to a non-existent method.
+      local panel = Panel({
+        bufname = "TestPanel",
+        config = Panel.default_config_split,
+      })
+      eq(nil, panel.get_winid)
+    end)
+  end)
+
+  describe("subclass contracts", function()
+    -- The actual panels used by the two view types must inherit the same
+    -- interface.
+
+    local function assert_panel_interface(panel_class, name)
+      it(name .. " inherits winid field", function()
+        eq(nil, rawget(panel_class, "get_winid"))
+      end)
+
+      it(name .. " inherits is_open method", function()
+        eq("function", type(panel_class.is_open))
+      end)
+    end
+
+    local FilePanel = require("diffview.scene.views.diff.file_panel").FilePanel
+    local FileHistoryPanel = require("diffview.scene.views.file_history.file_history_panel").FileHistoryPanel
+
+    assert_panel_interface(FilePanel, "FilePanel")
+    assert_panel_interface(FileHistoryPanel, "FileHistoryPanel")
+  end)
+end)