test: Configure coverage script

.gitignore

@@ -1,3 +1,5 @@
+/.nyc_output
+/coverage
 /node_modules
 npm-debug.log
 /package-lock.json

package.json

@@ -35,6 +35,7 @@
 		"bluebird": "^3.7.2",
 		"eslint": "^8.57.0",
 		"eslint-config-medikoo": "^4.2.0",
+		"nyc": "^15.1.0",
 		"plain-promise": "^0.1.1",
 		"prettier-elastic": "^3.2.5",
 		"tad": "^3.1.1"
@@ -50,6 +51,20 @@
 			"max-lines-per-function": "off"
 		}
 	},
+	"nyc": {
+		"all": true,
+		"exclude": [
+			".github",
+			"coverage/**",
+			"test/**",
+			"*.config.js"
+		],
+		"reporter": [
+			"lcov",
+			"html",
+			"text-summary"
+		]
+	},
 	"prettier": {
 		"printWidth": 100,
 		"tabWidth": 4,
@@ -66,6 +81,7 @@
 		]
 	},
 	"scripts": {
+		"coverage": "nyc npm test",
 		"lint": "eslint --ignore-path=.gitignore .",
 		"lint:updated": "pipe-git-updated --base=main --ext=js -- eslint --ignore-pattern '!*'",
 		"prettier-check": "prettier -c --ignore-path .gitignore \"**/*.{css,html,js,json,md,yaml,yml}\"",