test: add smoke test ensuring all rules make it into lib/index

tests/check-rules.js

@@ -0,0 +1,13 @@
+/* globals describe, it*/
+const config = require('../lib/index.js')
+const fs = require('fs')
+const assert = require('assert')
+const path = require('path')
+
+describe('smoke tests', () => {
+  it('ensure all rules in lib/rules are included in index', () => {
+    const exportedRules = new Set(Object.keys(config.rules))
+    const files = new Set(fs.readdirSync('./lib/rules').map(f => path.basename(f, path.extname(f))))
+    assert.deepEqual(files, exportedRules)
+  })
+})