Implementation:DevExpress Testcafe StackCleaningHook

Knowledge Sources	DevExpress_Testcafe TestCafe Docs
Domains	Error Handling, Developer Experience
Last Updated	2026-02-12 12:00 GMT

Overview

stackCleaningHook is a singleton object that filters internal TestCafe frames from error stack traces so that users see only their own code in error output.

Description

src/errors/stack-cleaning-hook.js exports a default singleton object with an enabled property and a cleanError method. When enabled, it:

1. Increases the stack trace limit -- Sets Error.stackTraceLimit to 200 (from the original default, typically 10) because Babel-generated errors can produce very deep stacks. When disabled, it restores the original limit.
2. Parses error frames -- Uses the error-stack-parser library to parse the error's .stack string into structured StackFrame objects.
3. Strips existing trace lines -- _removeStackTraceLines walks the stack string from the bottom and removes all lines matching the /^\s+at\s+.*$/ pattern, leaving only the error message portion.
4. Filters internal frames -- Applies a stack filter (created by createStackFilter) that removes frames originating from internal TestCafe code, keeping only user-relevant frames up to the original stack trace limit.
5. Re-renders the stack -- Appends the filtered frames' source strings back onto the cleaned error.stack.

The enabled getter/setter uses a guard to avoid redundant state changes and manages the Error.stackTraceLimit toggle as a side effect.

Usage

The hook is enabled just before test file compilation/execution and disabled immediately after (in finally blocks). The APIBasedTestFileCompilerBase enables it around _compileCodeForTestFiles and _runCompiledCode, calling cleanError(err) on caught errors before re-throwing them as TestCompilationError.

Code Reference

Source Location

src/errors/stack-cleaning-hook.js (83 lines)

Signature

export default {
    isEnabled: false,

    _isStackTraceLine (stackLine): boolean,
    _removeStackTraceLines (error): void,
    _getFrames (error): StackFrame[],
    _renderFrameInfo (frames): string,

    get enabled (): boolean,
    set enabled (val: boolean): void,

    cleanError (error): Error,
};

Import

import stackCleaningHook from '../../errors/stack-cleaning-hook';

I/O Contract

Inputs

Parameter	Type	Description
enabled (setter)	boolean	Toggles the hook on/off. When set to true, increases Error.stackTraceLimit to 200. When set to false, restores the original limit.
error (for cleanError)	Error	An error object whose .stack property will be cleaned of internal TestCafe frames.

Outputs

Method	Return Type	Description
cleanError(error)	Error	Returns the same error object with its .stack property rewritten to contain only user-relevant stack frames. If the error has no parseable frames, it is returned unmodified.
enabled (getter)	boolean	Returns the current enabled state of the hook.

Usage Examples

Enabling around compilation:

import stackCleaningHook from '../../errors/stack-cleaning-hook';

stackCleaningHook.enabled = true;

try {
    const compiled = compiler._precompileCode(testFilesInfo);
    return compiled;
}
catch (err) {
    throw new TestCompilationError(stackCleaningHook.cleanError(err));
}
finally {
    stackCleaningHook.enabled = false;
}

Enabling around test execution:

stackCleaningHook.enabled = true;

try {
    await this._execAsModule(compiledCode, filename);
}
catch (err) {
    if (!(err instanceof APIError))
        throw new TestCompilationError(stackCleaningHook.cleanError(err));
    throw err;
}
finally {
    stackCleaningHook.enabled = false;
}

Related Pages

• Implementation:DevExpress_Testcafe_ApiBasedCompiler -- Primary consumer that enables/disables the hook during compilation and execution
• Implementation:DevExpress_Testcafe_ErrorTypes -- Defines the error codes for errors that get their stacks cleaned by this hook