test: update tests to use Error.isError instead of util.isError on newer node versions

Author: Phillip9587

test/test.js

@@ -6,9 +6,21 @@ var util = require('util')
 
 var createError = require('..')
 
+// eslint-disable-next-line node/no-deprecated-api
+var isError = typeof Error.isError === 'function' ? Error.isError : util.isError
+
+var itErrorIsError = typeof Error.isError === 'function'
+  ? it
+  : it.skip
+
+// eslint-disable-next-line node/no-deprecated-api
+var itUtilIsError = typeof util.isError === 'function'
+  ? it
+  : it.skip
+
 describe('createError(status)', function () {
   it('should create error object', function () {
-    assert.ok(util.isError(createError(500))) // eslint-disable-line node/no-deprecated-api
+    assert.ok(isError(createError(500)))
   })
 
   describe('Extending Existing Errors with HTTP Properties', function () {
@@ -126,7 +138,7 @@ describe('createError(status, message)', function () {
   })
 
   it('should create error object', function () {
-    assert.ok(util.isError(this.error)) // eslint-disable-line node/no-deprecated-api
+    assert.ok(isError(this.error))
   })
 
   it('should have "message" property with message', function () {
@@ -419,11 +431,17 @@ describe('HTTP Errors', function () {
     assert((new createError['500']()) instanceof createError.HttpError)
   })
 
-  it('should support util.isError()', function () {
+  itUtilIsError('should support util.isError()', function () {
     /* eslint-disable node/no-deprecated-api */
     assert(util.isError(createError(404)))
     assert(util.isError(new createError['404']()))
     assert(util.isError(new createError['500']()))
     /* eslint-enable node/no-deprecated-api */
   })
+
+  itErrorIsError('should support Error.isError()', function () {
+    assert(Error.isError(createError(404)))
+    assert(Error.isError(new createError['404']()))
+    assert(Error.isError(new createError['500']()))
+  })
 })