tests/indent: add multiple C/C++ tests

lua/tests/indent/cpp_spec.lua

@@ -0,0 +1,23 @@
+local whole_file = require('nvim-treesitter.test_utils').indent_whole_file
+local scan_dir = require('plenary.scandir').scan_dir
+local Path = require('plenary.path')
+
+describe('indent C++:', function()
+  describe('whole file:', function()
+    local files = scan_dir('lua/tests/indent/c');
+    vim.list_extend(files, scan_dir('lua/tests/indent/cpp'))
+
+    for _, file in ipairs(files) do
+      local name = Path:new(file):make_relative('lua/tests/indent')
+      it(name, function()
+        whole_file(file, {
+          tabstop = 4,
+          shiftwidth = 4,
+          softtabstop = 0,
+          expandtab = true,
+          filetype = 'cpp',
+        })
+      end)
+    end
+  end)
+end)