Skip to content

split err.stack so embedded stacks in err message render once #5997

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
mostafaNazari702 wants to merge 1 commit into
base: main
Choose a base branch
from
+63 −18
Open

split err.stack so embedded stacks in err message render once #5997

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
56 changes: 38 additions & 18 deletions lib/reporters/base.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -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");

@JoshuaKGoldberg JoshuaKGoldberg Jun 7, 2026

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[Bug] Make sure this handles a trailing \n well - we don't want the last line to be "".

var frameStart = lines.length;
for (var i = lines.length - 1; i >= 0; i--) {

@JoshuaKGoldberg JoshuaKGoldberg Jun 7, 2026

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[Bug] For an Error-like object with a stack containing only V8 frame lines:

{
  message: "Boom",
  stack: "    at fn (foo.js:1:1)\n    at run (foo.js:2:2)"
}

This'll make msg "".

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,
Expand Down
25 changes: 25 additions & 0 deletions test/reporters/base.spec.js
View file
Open in desktop

@JoshuaKGoldberg JoshuaKGoldberg Jun 7, 2026

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[Testing] This is really tricky stuff. Stack frames get surprisingly weirdly crafted in practice. A couple more test cases to add...

When the stack only contains frames:

var err = {
  message: "Error",
  stack: "    at foo (foo.js:1:1)\n    at bar (bar.js:2:2)",
  showDiff: false,
};
var test = makeTest(err);

Error output should be something like 1) test title:\n Error\n at foo (foo.js:1:1)\n at bar (bar.js:2:2).

When the embedded stack has a trailing newline, like:

var embeddedMessage =
  "An error occured with following trace:\n\nError\n    at inner (/original/foo.js:1:1)";
var stackMessage = embeddedMessage.replace(/\/original\//g, "/filtered/");
var err = {
  message: embeddedMessage,
  stack:
    "Error: " + stackMessage + "\n    at runTest (lib/runner.js:1:1)\n",
  showDiff: false,
};

The output still should smartly parse & not duplicate.

Original file line number Diff line number Diff line change
Expand Up @@ -568,6 +568,31 @@ describe("Base reporter", function () {
);
});

it("should not duplicate the message when it contains an embedded stack", function () {

@JoshuaKGoldberg JoshuaKGoldberg Jun 7, 2026

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[Testing] This passes on the original implementation:

git checkout main -- test/reporters/base.spec.js
npx mocha test/reporters/base.spec.js

The test should simulate the actual mismatch from the issue: err.message contains an embedded stack, but err.stack has the embedded stack slightly rewritten.

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",
Expand Down
Loading