Fix: Make multiple calls to setup() independent

Previously, multiple calls to `gruvbox.setup()` would merge configurations,
leading to unexpected behavior when trying to reset or change specific
settings like `overrides` or `contrast`.

This commit addresses the issue by ensuring that each call to `setup()`
starts with a fresh copy of the default configuration before applying
the user-provided settings.

This change makes calls to `setup()` idempotent and independent of
previous calls, as suggested in issue #402.

A new test case has been added to verify this behavior.

1 files changed, 4 insertions, 1 deletions

diff --git a/lua/gruvbox.lua b/lua/gruvbox.lua
index cd81874..6a5ef41 100644
--- a/lua/gruvbox.lua
+++ b/lua/gruvbox.lua
@@ -44,7 +44,7 @@ local Gruvbox = {}
 ---@field transparent_mode boolean?
 ---@field undercurl boolean?
 ---@field underline boolean?
-Gruvbox.config = {
+local default_config = {
   terminal_colors = true,
   undercurl = true,
   underline = true,
@@ -68,6 +68,8 @@ Gruvbox.config = {
   transparent_mode = false,
 }
 
+Gruvbox.config = vim.deepcopy(default_config)
+
 -- main gruvbox color palette
 ---@class GruvboxPalette
 Gruvbox.palette = {
@@ -1311,6 +1313,7 @@ end
 
 ---@param config GruvboxConfig?
 Gruvbox.setup = function(config)
+  Gruvbox.config = vim.deepcopy(default_config)
   Gruvbox.config = vim.tbl_deep_extend("force", Gruvbox.config, config or {})
 end