1 files changed, 24 insertions, 3 deletions
diff --git a/lib/assert.js b/lib/assert.js
index a1b22d3e46..035a7e1746 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -20,7 +20,7 @@
 
 'use strict';
 
-const { Object } = primordials;
+const { Object, ObjectPrototype } = primordials;
 
 const { Buffer } = require('buffer');
 const { codes: {
@@ -36,6 +36,7 @@ const { inspect } = require('internal/util/inspect');
 const { isPromise, isRegExp } = require('internal/util/types');
 const { EOL } = require('internal/constants');
 const { NativeModule } = require('internal/bootstrap/loaders');
+const { isError } = require('internal/util');
 
 const errorCache = new Map();
 
@@ -561,6 +562,8 @@ function compareExceptionKey(actual, expected, key, message, keys, fn) {
 }
 
 function expectedException(actual, expected, message, fn) {
+  let generatedMessage = false;
+
   if (typeof expected !== 'function') {
     // Handle regular expressions.
     if (isRegExp(expected)) {
@@ -618,8 +621,26 @@ function expectedException(actual, expected, message, fn) {
   if (expected.prototype !== undefined && actual instanceof expected) {
     return;
   }
-  if (Error.isPrototypeOf(expected)) {
-    throw actual;
+  if (ObjectPrototype.isPrototypeOf(Error, expected)) {
+    if (!message) {
+      generatedMessage = true;
+      message = 'The error is expected to be an instance of ' +
+        `"${expected.name}". Received `;
+      if (isError(actual)) {
+        message += `"${actual.name}"`;
+      } else {
+        message += `"${inspect(actual, { depth: -1 })}"`;
+      }
+    }
+    const err = new AssertionError({
+      actual,
+      expected,
+      message,
+      operator: fn.name,
+      stackStartFn: fn
+    });
+    err.generatedMessage = generatedMessage;
+    throw err;
   }
 
   // Check validation functions return value.