fix: prevent error when user pass a nil value to setup

added more tests and makefile

docker-compose.yml

@@ -1,8 +1,3 @@
 services:
   solarized:
     build: .
-    volumes:
-      - solarized:/solarized
-
-volumes:
-  solarized:

lua/solarized/init.lua

@@ -9,7 +9,7 @@ local M = {}
 M.config = require 'solarized.config'
 
 M.setup = function(config)
-  M.config = vim.tbl_deep_extend('force', M.config, config)
+  M.config = vim.tbl_deep_extend('force', M.config, config or {})
 
   if M.config.styles.enabled == false then
     M.config.styles = {

makefile

@@ -0,0 +1,4 @@
+fmt:
+	stylua -f ./stylua.toml .
+test:
+	vusted ./tests

tests/setup_spec.lua

@@ -46,4 +46,27 @@ describe('solarized.setup', function()
     assert.True(strings.italic)
     assert.True(comments.bold)
   end)
+
+  test('styles.enabled', function()
+    local solarized = require 'solarized'
+    solarized.setup {
+      styles = {
+        enabled = false,
+        strings = { italic = true },
+        comments = { bold = true },
+      },
+    }
+    vim.cmd 'colorscheme solarized'
+
+    local strings = nvim_get_hl 'String'
+    local comments = nvim_get_hl 'Comment'
+    assert.Nil(strings.italic)
+    assert.Nil(comments.bold)
+  end)
+
+  test('nil config', function()
+    local solarized = require 'solarized'
+    solarized.setup()
+    vim.cmd 'colorscheme solarized'
+  end)
 end)