Use is-plain-obj

package.json

@@ -34,6 +34,7 @@
     "abstract-parser": "^0.1.0",
     "chalk": "^2.4.2",
     "core-js": "^3.2.1",
+    "is-plain-obj": "^2.0.0",
     "jest-validate": "^24.9.0",
     "supports-color": "^7.0.0",
     "yargs": "^14.0.0"

src/options.js

@@ -1,6 +1,5 @@
 import { validate } from 'jest-validate'
-
-import { isPlainObject } from './utils.js'
+import isPlainObj from 'is-plain-obj'
 
 // Validate options and assign default values
 export const handleOpts = function(opts, defaultOpts, exampleConfig) {
@@ -11,7 +10,7 @@ export const handleOpts = function(opts, defaultOpts, exampleConfig) {
 }
 
 export const validateBasicOpts = function(opts) {
-  if (!isPlainObject(opts)) {
+  if (!isPlainObj(opts)) {
     throw new TypeError(`Options must be a plain object: ${opts}`)
   }
 }

src/utils.js

@@ -1,13 +1,3 @@
-// Is a plain object, including `Object.create(null)`
-export const isPlainObject = function(val) {
-  return (
-    typeof val === 'object' &&
-    val !== null &&
-    // istanbul ignore next
-    (val.constructor === Object || val.constructor === undefined)
-  )
-}
-
 // Like lodash _.omitBy()
 export const omitBy = function(object, condition) {
   const pairs = Object.entries(object)