From 9ad464bd38f231ed60d7932fe5df9030cfa69534 Mon Sep 17 00:00:00 2001
From: mostafanazari702 <nazarimostafa2006@gmail.com>
Date: Fri, 22 May 2026 23:37:48 +0200
Subject: [PATCH] split err.stack at the trailing frame block so embedded
 stacks in err.message render once

---
 lib/reporters/base.js       | 56 +++++++++++++++++++++++++------------
 test/reporters/base.spec.js | 25 +++++++++++++++++
 2 files changed, 63 insertions(+), 18 deletions(-)

diff --git a/lib/reporters/base.js b/lib/reporters/base.js
index 4a0bae09b9..a5a2b5e511 100644
--- a/lib/reporters/base.js
+++ b/lib/reporters/base.js
@@ -404,38 +404,58 @@ var getFullErrorStack = function (err, seen) {
   }
 
   var message;
+  var usedInspect = false;
 
   if (typeof err.inspect === "function") {
     message = err.inspect() + "";
+    usedInspect = true;
   } else if (err.message && typeof err.message.toString === "function") {
     message = err.message + "";
   } else {
     message = "";
   }
 
-  var msg;
-  var stack = err.stack || message;
-  var index = message ? stack.indexOf(message) : -1;
+  var rawStack = err.stack || message;
+  var lines = rawStack.split("\n");
+  var frameStart = lines.length;
+  for (var i = lines.length - 1; i >= 0; i--) {
+    if (/^\s+at\s/.test(lines[i])) {
+      frameStart = i;
+    } else {
+      break;
+    }
+  }
 
-  if (index === -1) {
-    msg = message;
+  var msg;
+  var stack;
+  var splitSucceeded = false;
+  if (frameStart < lines.length) {
+    stack = lines.slice(frameStart).join("\n");
+    msg = usedInspect ? message : lines.slice(0, frameStart).join("\n");
+    splitSucceeded = true;
   } else {
-    index += message.length;
-    msg = stack.slice(0, index);
-    // remove msg from stack
-    stack = stack.slice(index + 1);
-
-    if (err.cause) {
-      seen = seen || new Set();
-      seen.add(err);
-      const causeStack = getFullErrorStack(err.cause, seen);
-      stack +=
-        "\n   Caused by: " +
-        causeStack.msg +
-        (causeStack.stack ? "\n" + causeStack.stack : "");
+    var index = message ? rawStack.indexOf(message) : -1;
+    if (index === -1) {
+      msg = message;
+      stack = rawStack;
+    } else {
+      index += message.length;
+      msg = rawStack.slice(0, index);
+      stack = rawStack.slice(index + 1);
+      splitSucceeded = true;
     }
   }
 
+  if (splitSucceeded && err.cause) {
+    seen = seen || new Set();
+    seen.add(err);
+    const causeStack = getFullErrorStack(err.cause, seen);
+    stack +=
+      "\n   Caused by: " +
+      causeStack.msg +
+      (causeStack.stack ? "\n" + causeStack.stack : "");
+  }
+
   return {
     message,
     msg,
diff --git a/test/reporters/base.spec.js b/test/reporters/base.spec.js
index d74e009e54..a8beaca0d0 100644
--- a/test/reporters/base.spec.js
+++ b/test/reporters/base.spec.js
@@ -568,6 +568,31 @@ describe("Base reporter", function () {
       );
     });
 
+    it("should not duplicate the message when it contains an embedded stack", function () {
+      var embeddedMessage =
+        "An error occured with following trace:\n\nError\n    at inner (foo.js:1:1)\n    at outer (foo.js:2:2)";
+      var err = {
+        message: embeddedMessage,
+        stack:
+          "Error: " +
+          embeddedMessage +
+          "\n    at outer (foo.js:2:2)\n    at runTest (lib/runner.js:1:1)",
+        showDiff: false,
+      };
+      var test = makeTest(err);
+
+      list([test]);
+
+      var errOut = stdout.join("\n").trim();
+      expect(
+        errOut.match(/Error: An error occured with following trace:/g),
+        "to have length",
+        1,
+      );
+      expect(errOut, "to contain", "at runTest (lib/runner.js:1:1)");
+      expect(errOut.match(/at inner \(foo\.js:1:1\)/g), "to have length", 1);
+    });
+
     it("should not add cause trail if error does not contain message", function () {
       var err = {
         message: "Error",