plugins/nvim-ufo: init + test (#446)

tests/test-sources/plugins/utils/nvim-ufo.nix

@@ -0,0 +1,72 @@
+{
+  empty = {
+    plugins.nvim-ufo.enable = true;
+  };
+
+  example = {
+    plugins.nvim-ufo = {
+      enable = true;
+      providerSelector = ''
+        function(bufnr, filetype, buftype)
+          local ftMap = {
+            vim = "indent",
+            python = {"indent"},
+            git = ""
+          }
+
+         return ftMap[filetype]
+        end
+      '';
+
+      foldVirtTextHandler = ''
+        function(virtText, lnum, endLnum, width, truncate)
+          local newVirtText = {}
+          local suffix = ('  %d '):format(endLnum - lnum)
+          local sufWidth = vim.fn.strdisplaywidth(suffix)
+          local targetWidth = width - sufWidth
+          local curWidth = 0
+          for _, chunk in ipairs(virtText) do
+            local chunkText = chunk[1]
+            local chunkWidth = vim.fn.strdisplaywidth(chunkText)
+            if targetWidth > curWidth + chunkWidth then
+              table.insert(newVirtText, chunk)
+            else
+              chunkText = truncate(chunkText, targetWidth - curWidth)
+              local hlGroup = chunk[2]
+              table.insert(newVirtText, {chunkText, hlGroup})
+              chunkWidth = vim.fn.strdisplaywidth(chunkText)
+              -- str width returned from truncate() may less than 2nd argument, need padding
+              if curWidth + chunkWidth < targetWidth then
+                suffix = suffix .. (' '):rep(targetWidth - curWidth - chunkWidth)
+              end
+              break
+            end
+            curWidth = curWidth + chunkWidth
+          end
+          table.insert(newVirtText, {suffix, 'MoreMsg'})
+          return newVirtText
+        end
+      '';
+    };
+  };
+
+  defaults = {
+    plugins.nvim-ufo = {
+      enable = true;
+      openFoldHlTimeout = 400;
+      providerSelector = null;
+      closeFoldKinds = {};
+      foldVirtTextHandler = null;
+      enableGetFoldVirtText = false;
+      preview = {
+        winConfig = {
+          border = "rounded";
+          winblend = 12;
+          winhighlight = "Normal:Normal";
+          maxheight = 20;
+        };
+        mappings = {};
+      };
+    };
+  };
+}