(mini.operators) Update default_evaluate_func() to not modify input.

Author: echasnovski

lua/mini/operators.lua

@@ -710,10 +710,11 @@ H.create_default_hl =
 
 -- Evaluate -------------------------------------------------------------------
 H.eval_lua_lines = function(lines)
-  local n = #lines
-  lines[n] = (lines[n]:find('^%s*return%s+') == nil and 'return ' or '') .. lines[n]
+  -- Copy to not modify input
+  local lines_copy, n = vim.deepcopy(lines), #lines
+  lines_copy[n] = (lines_copy[n]:find('^%s*return%s+') == nil and 'return ' or '') .. lines_copy[n]
 
-  local str_to_eval = table.concat(lines, '\n')
+  local str_to_eval = table.concat(lines_copy, '\n')
 
   -- Allow returning tuple with any value(s) being `nil`
   return H.inspect_objects(assert(loadstring(str_to_eval))())

tests/test_operators.lua

@@ -338,6 +338,22 @@ T['default_evaluate_func()']['works for blockwise'] = function()
   validate({ '_G.y + 1' }, { '2' })
 end
 
+T['default_evaluate_func()']['does not modify input'] = function()
+  local validate = function(content)
+    local lua_cmd = string.format(
+      [[_G.content = %s
+        MiniOperators.default_evaluate_func(_G.content)]],
+      vim.inspect(content)
+    )
+    child.lua(lua_cmd)
+    eq(child.lua_get('_G.content'), content)
+  end
+
+  validate({ lines = { '1 + 1' }, submode = 'v' })
+  validate({ lines = { '1 + 1' }, submode = 'V' })
+  validate({ lines = { '1 + 1', '1 + 2' }, submode = '\22' })
+end
+
 T['default_evaluate_func()']['validates arguments'] = function()
   expect.error(default_evaluate_func, '`content`', 1)
   expect.error(default_evaluate_func, '`content`', {})