build: update lint system and coverage

package.json

@@ -19,6 +19,7 @@
     "version": "conventional-changelog -i changelog.md -s -r 0 && git commit -am \"build: update changelog\"",
     "prepare": "npm run build",
     "build": "rimraf lib && babel src -d lib",
+    "coverage": "nyc report --reporter=text-lcov | coveralls",
     "test": "nyc ava"
   },
   "files": [
@@ -56,11 +57,13 @@
     "coveralls": "^3.0.3",
     "eslint": "^5.16.0",
     "eslint-config-xo": "^0.26.0",
+    "eslint-config-xo-space": "^0.21.0",
     "eslint-plugin-ava": "^7.0.0",
     "eslint-plugin-babel": "^5.3.0",
     "eslint-plugin-dependencies": "^2.4.0",
     "eslint-plugin-html": "^5.0.5",
     "eslint-plugin-markdown": "^1.0.0",
+    "eslint-plugin-prettier": "^3.1.0",
     "eslint-plugin-unicorn": "^9.0.0",
     "husky": "^2.4.0",
     "lint-staged": "^8.1.7",
@@ -108,24 +111,20 @@
   "eslintConfig": {
     "parser": "babel-eslint",
     "plugins": [
+      "prettier",
       "dependencies",
       "html",
       "unicorn",
       "babel",
       "markdown"
     ],
     "extends": [
+      "plugin:ava/recommended",
       "plugin:unicorn/recommended",
-      "xo"
+      "xo",
+      "xo-space"
     ],
     "rules": {
-      "indent": [
-        2,
-        4,
-        {
-          "SwitchCase": 1
-        }
-      ],
       "capitalized-comments": "off"
     }
   },