From ffb2522eb94afe46a8ccc23faebdcee23ea6f170 Mon Sep 17 00:00:00 2001
From: Kotaro Hirayama <just.do.it.my.life@gmail.com>
Date: Wed, 18 Apr 2018 17:59:17 +0900
Subject: [PATCH] [Breaking] ensure `Error` objects compare properly

---
 .eslintrc   |  1 +
 index.js    | 10 +++++++++-
 test/cmp.js |  8 ++++++++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/.eslintrc b/.eslintrc
index 4ff2c50..4fb86e1 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -16,6 +16,7 @@
       "files": ["example/**", "test/**"],
       "rules": {
         "array-bracket-newline": 0,
+        "max-lines": 0,
         "max-params": 0,
         "max-statements": 0,
         "no-console": 0,
diff --git a/index.js b/index.js
index 61307f3..d980db2 100644
--- a/index.js
+++ b/index.js
@@ -50,7 +50,7 @@ function isBuffer(x) {
 }
 
 function objEquiv(a, b, opts) {
-  /* eslint max-statements: [2, 50] */
+  /* eslint max-statements: [2, 70] */
   var i, key;
   if (typeof a !== typeof b) { return false; }
   if (isUndefinedOrNull(a) || isUndefinedOrNull(b)) { return false; }
@@ -60,6 +60,14 @@ function objEquiv(a, b, opts) {
 
   if (isArguments(a) !== isArguments(b)) { return false; }
 
+  // TODO: replace when a cross-realm brand check is available
+  var aIsError = a instanceof Error;
+  var bIsError = b instanceof Error;
+  if (aIsError !== bIsError) { return false; }
+  if (aIsError || bIsError) {
+    if (a.name !== b.name || a.message !== b.message) { return false; }
+  }
+
   var aIsRegex = isRegex(a);
   var bIsRegex = isRegex(b);
   if (aIsRegex !== bIsRegex) { return false; }
diff --git a/test/cmp.js b/test/cmp.js
index b377743..538e827 100644
--- a/test/cmp.js
+++ b/test/cmp.js
@@ -342,3 +342,11 @@ test('functions', function (t) {
 
   t.end();
 });
+
+test('Errors', function (t) {
+  t.deepEqualTest(new Error('xyz'), new Error('xyz'), 'two errors of the same type with the same message', true, true, false);
+  t.deepEqualTest(new Error('xyz'), new TypeError('xyz'), 'two errors of different types with the same message', false, false);
+  t.deepEqualTest(new Error('xyz'), new Error('zyx'), 'two errors of the same type with a different message', false, false);
+
+  t.end();
+});