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[tests] Add \n in <stack> placeholder for native stacks #35496

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rickhanlonii wants to merge 4 commits into from
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[tests] Add \n in <stack> placeholder for native stacks #35496

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326cea2
Add full component stacks to console error assertions
rickhanlonii Jan 9, 2026
4cffcc1
fix build test
rickhanlonii Jan 12, 2026
6e8deb0
add internaltestutil changes
rickhanlonii Jan 12, 2026
f87b7d0
Add [Server] and error stack placeholders to console assertions
rickhanlonii Jan 9, 2026
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127 changes: 123 additions & 4 deletions packages/internal-test-utils/__tests__/ReactInternalTestUtils-test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1606,7 +1606,7 @@ describe('ReactInternalTestUtils console assertions', () => {
it('fails if component stack is passed twice', () => {
const message = expectToThrowFailure(() => {
console.warn('Hi %s%s', '\n in div', '\n in div');
assertConsoleWarnDev(['Hi']);
assertConsoleWarnDev(['Hi \n in div (at **)']);
});
expect(message).toMatchInlineSnapshot(`
"assertConsoleWarnDev(expected)
Expand All @@ -1621,7 +1621,10 @@ describe('ReactInternalTestUtils console assertions', () => {
const message = expectToThrowFailure(() => {
console.warn('Hi %s%s', '\n in div', '\n in div');
console.warn('Bye %s%s', '\n in div', '\n in div');
assertConsoleWarnDev(['Hi', 'Bye']);
assertConsoleWarnDev([
'Hi \n in div (at **)',
'Bye \n in div (at **)',
]);
});
expect(message).toMatchInlineSnapshot(`
"assertConsoleWarnDev(expected)
Expand Down Expand Up @@ -2678,7 +2681,7 @@ describe('ReactInternalTestUtils console assertions', () => {
it('fails if component stack is passed twice', () => {
const message = expectToThrowFailure(() => {
console.error('Hi %s%s', '\n in div', '\n in div');
assertConsoleErrorDev(['Hi']);
assertConsoleErrorDev(['Hi \n in div (at **)']);
});
expect(message).toMatchInlineSnapshot(`
"assertConsoleErrorDev(expected)
Expand All @@ -2693,7 +2696,10 @@ describe('ReactInternalTestUtils console assertions', () => {
const message = expectToThrowFailure(() => {
console.error('Hi %s%s', '\n in div', '\n in div');
console.error('Bye %s%s', '\n in div', '\n in div');
assertConsoleErrorDev(['Hi', 'Bye']);
assertConsoleErrorDev([
'Hi \n in div (at **)',
'Bye \n in div (at **)',
]);
});
expect(message).toMatchInlineSnapshot(`
"assertConsoleErrorDev(expected)
Expand Down Expand Up @@ -2752,6 +2758,119 @@ describe('ReactInternalTestUtils console assertions', () => {
assertConsoleErrorDev(['Hi', 'Wow', 'Bye']);
});

describe('\\n in <stack> placeholder', () => {
// @gate __DEV__
it('fails if \\n in <stack> is used for a component stack instead of an error stack', () => {
const message = expectToThrowFailure(() => {
console.error('Warning message\n in div');
assertConsoleErrorDev(['Warning message\n in <stack>']);
});
expect(message).toMatchInlineSnapshot(`
"assertConsoleErrorDev(expected)

Incorrect use of \\n in <stack> placeholder. The placeholder is for JavaScript Error stack traces (messages starting with "Error:"), not for React component stacks.

Expected: "Warning message
in <stack>"
Received: "Warning message
in div (at **)"

If this error has a component stack, include the full component stack in your expected message (e.g., "Warning message\\n in ComponentName (at **)")."
`);
});

// @gate __DEV__
it('fails if \\n in <stack> is used for multiple component stacks', () => {
const message = expectToThrowFailure(() => {
console.error('First warning\n in span');
console.error('Second warning\n in div');
assertConsoleErrorDev([
'First warning\n in <stack>',
'Second warning\n in <stack>',
]);
});
expect(message).toMatchInlineSnapshot(`
"assertConsoleErrorDev(expected)

Incorrect use of \\n in <stack> placeholder. The placeholder is for JavaScript Error stack traces (messages starting with "Error:"), not for React component stacks.

Expected: "First warning
in <stack>"
Received: "First warning
in span (at **)"

If this error has a component stack, include the full component stack in your expected message (e.g., "Warning message\\n in ComponentName (at **)").

Incorrect use of \\n in <stack> placeholder. The placeholder is for JavaScript Error stack traces (messages starting with "Error:"), not for React component stacks.

Expected: "Second warning
in <stack>"
Received: "Second warning
in div (at **)"

If this error has a component stack, include the full component stack in your expected message (e.g., "Warning message\\n in ComponentName (at **)")."
`);
});

// @gate __DEV__
it('allows \\n in <stack> for actual error stack traces', () => {
// This should pass - \n in <stack> is correctly used for an error stack
console.error(
'Error: Something went wrong\n at someFunction (file.js:10:5)\n at anotherFunction (file.js:20:10)'
);
assertConsoleErrorDev(['Error: Something went wrong\n in <stack>']);
});

// @gate __DEV__
it('fails if error stack trace is present but \\n in <stack> is not expected', () => {
const message = expectToThrowFailure(() => {
console.error(
'Error: Something went wrong\n at someFunction (file.js:10:5)'
);
assertConsoleErrorDev(['Error: Something went wrong']);
});
expect(message).toMatchInlineSnapshot(`
"assertConsoleErrorDev(expected)

Unexpected error stack trace for:
"Error: Something went wrong
in someFunction (at **)"

If this error should include an error stack trace, add \\n in <stack> to your expected message (e.g., "Error: message\\n in <stack>")."
`);
});

// @gate __DEV__
it('fails if \\n in <stack> is expected but no stack is present', () => {
const message = expectToThrowFailure(() => {
console.error('Error: Something went wrong');
assertConsoleErrorDev([
'Error: Something went wrong\n in <stack>',
]);
});
expect(message).toMatchInlineSnapshot(`
"assertConsoleErrorDev(expected)

Missing error stack trace for:
"Error: Something went wrong"

The expected message uses \\n in <stack> but the actual error doesn't include an error stack trace.
If this error should not have an error stack trace, remove \\n in <stack> from your expected message."
`);
});
});

describe('[Server] placeholder', () => {
// @gate __DEV__
it('expands [Server] to ANSI escape sequence for server badge', () => {
const serverBadge = '\u001b[0m\u001b[7m Server \u001b[0m';
console.error(serverBadge + 'Error: something went wrong');
assertConsoleErrorDev([
['[Server] Error: something went wrong', {withoutStack: true}],
]);
});
});

it('should fail if waitFor is called before asserting', async () => {
const Yield = ({id}) => {
Scheduler.log(id);
Expand Down
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