fix: avoid recursion when copying folder to itself

lua/plenary/path.lua

@@ -548,6 +548,7 @@ function Path:copy(opts)
   end
   -- dir
   if opts.recursive then
+    local suffix = table.remove(self:_split())
     dest:mkdir {
       parents = F.if_nil(opts.parents, false, opts.parents),
       exists_ok = F.if_nil(opts.exists_ok, true, opts.exists_ok),
@@ -561,13 +562,16 @@ function Path:copy(opts)
     })
     for _, entry in ipairs(data) do
       local entry_path = Path:new(entry)
-      local suffix = table.remove(entry_path:_split())
-      local new_dest = dest:joinpath(suffix)
-      -- clear destination as it might be Path table otherwise failing w/ extend
-      opts.destination = nil
-      local new_opts = vim.tbl_deep_extend("force", opts, { destination = new_dest })
-      -- nil: not overriden if `override = false`
-      success[new_dest] = entry_path:copy(new_opts) or false
+      local entry_suffix = table.remove(entry_path:_split())
+      -- avoid repeated recursive copying if folder is copied into itself
+      if suffix ~= entry_suffix then
+        local new_dest = dest:joinpath(entry_suffix)
+        -- clear destination as it might be Path table otherwise failing w/ extend
+        opts.destination = nil
+        local new_opts = vim.tbl_deep_extend("force", opts, { destination = new_dest })
+        -- nil: not overriden if `override = false`
+        success[new_dest] = entry_path:copy(new_opts) or false
+      end
     end
     return success
   else

tests/plenary/path_spec.lua

@@ -478,6 +478,49 @@ describe("Path", function()
       src_dir:rm { recursive = true }
     end)
 
+    it("self copies folders only once", function()
+      local scan = require "plenary.scandir"
+      -- create nested folder
+      local src_dir = Path:new "src"
+      src_dir:mkdir()
+      src_dir:joinpath("file1.lua"):touch()
+      local src_sub_dir = src_dir:joinpath "sub_dir"
+      src_sub_dir:mkdir()
+      src_sub_dir:joinpath("file2.lua"):touch()
+      -- src
+      -- ├── file1.lua
+      -- └── sub_dir
+      --     └── file2_2.lua
+
+      local trg_dir = src_dir:joinpath "src"
+      src_dir:copy { destination = trg_dir, recursive = true }
+      -- src/
+      -- ├── file1.lua
+      -- ├── src
+      -- │   ├── file1.lua
+      -- │   └── sub_dir
+      -- │       └── file2.lua
+      -- └── sub_dir
+      --     └── file2.lua
+      local src_dir_data = scan.scan_dir(src_dir:absolute(), { depth = 1, add_dirs = true })
+      local trg_dir_data = scan.scan_dir(trg_dir:absolute(), { depth = 1, add_dirs = true })
+      table.insert(trg_dir_data, trg_dir:absolute())
+      -- check that equal number of items
+      assert(#src_dir_data == #trg_dir_data)
+      -- insert file/folder stems into set
+      local path_set = {}
+      -- get suffixes of absolute paths in respective folders and check match by creating set
+      for _, value in ipairs(src_dir_data) do
+        value = table.remove(Path:new(value):_split())
+        path_set[value] = true
+      end
+      for _, value in ipairs(trg_dir_data) do
+        value = table.remove(Path:new(value):_split())
+        assert(path_set[value])
+      end
+      src_dir:rm { recursive = true }
+    end)
+
     it("can copy directories recursively", function()
       -- vim.tbl_flatten doesn't work here as copy doesn't return a list
       local flatten