Class AssertionFailure<T>

This error is thrown when the requested assertion check fails.

Extends standard Error class
- AssertionError is a base class of this error
  - AssertionFailure - This class
    - AssertionFatal Use for fatal assertion issues

Param: message

The message for the error.

Param: props

The additional properties for the error.

Param: stackStart

The function to use as the starting point for the stack trace.

Returns

The new AssertionFailure instance.

Example

interface CustomProps {
    expected: number;
    actual: number;
}

try {
   throw new AssertionFailure<CustomProps>("Expected value does not match actual value", { expected: 1, actual: 2 });
} catch (e) {
  console.error(e.fullStack);
  console.log(e.toJSON());
}

console.error(error.message); // "Expected value does not match actual value"
console.log(error.props?.expected); // 1
console.log(error.props?.actual); // 2

Type Parameters

T
The type of the additional properties.

AssertionFailure<T>(
    message?: string,
    props?: T,
    stackStart?: Function | Function[],
): AssertionFailure<T>
Static Hideconstructor
Creates a new AssertionFailure with the given message and properties.
Type Parameters
- T
  The type of the additional properties.
Parameters
- Optionalmessage: string
  The message for the error.
- Optionalprops: T
  The additional properties for the error.
- OptionalstackStart: Function | Function[]
  The function to use as the starting point for the stack trace.
Returns AssertionFailure<T>
The new AssertionFailure.
Example
```
try {
   throw new AssertionFailure("Assertion failed", { expected: 1, actual: 2 });
} catch (e) {
  console.error(e.fullStack);
 console.log(e.toJSON());
}
```
- Defined in assert/assertionError.ts:557
- Defined in assert/assertionError.ts:679
AssertionFailure<T>(
    message?: string,
    innerEx?: Error,
    props?: T,
    stackStart?: Function | Function[],
): AssertionFailure<T>
Static Hideconstructor
Creates a new AssertionFailure with the given message and properties.
Type Parameters
- T
  The type of the additional properties.
Parameters
- Optionalmessage: string
  The message for the error.
- OptionalinnerEx: Error
  The error that caused this error to be thrown.
- Optionalprops: T
  The additional properties for the error.
- OptionalstackStart: Function | Function[]
  The function to use as the starting point for the stack trace.
Returns AssertionFailure<T>
The new AssertionFailure.
Example
```
try {
   throw new AssertionFailure("Assertion failed", new Error(), { expected: 1, actual: 2 });
} catch (e) {
  console.error(e.fullStack);
 console.log(e.toJSON());
}
```
- Defined in assert/assertionError.ts:557
- Defined in assert/assertionError.ts:679
AssertionFailure<T>(
    message?: string,
    props?: T,
    stackStart?: Function | Function[],
): AssertionError<T>
Static
Creates a new AssertionError with the given message and properties.
Type Parameters
- T
  The type of the additional properties.
Parameters
- Optionalmessage: string
  The message for the error.
- Optionalprops: T
  The additional properties for the error.
- OptionalstackStart: Function | Function[]
  An array of possible functions to use as the starting point for the stack trace.
Returns AssertionError<T>
The new AssertionError.
- Defined in assert/assertionError.ts:557
- Defined in assert/assertionError.ts:679
AssertionFailure<T>(
    message?: string,
    innerEx?: Error,
    props?: T,
    stackStart?: Function | Function[],
): AssertionError<T>
Static
Creates a new AssertionError with the given message and properties.
Type Parameters
- T
  The type of the additional properties.
Parameters
- Optionalmessage: string
  The message for the error.
- OptionalinnerEx: Error
  The error that caused this error to be thrown.
- Optionalprops: T
  The additional properties for the error.
- OptionalstackStart: Function | Function[]
  An array of possible functions to use as the starting point for the stack trace.
Returns AssertionError<T>
The new AssertionError.
- Defined in assert/assertionError.ts:557
- Defined in assert/assertionError.ts:679
AssertionFailure(message?: string): AssertionError
Static
Parameters
- Optionalmessage: string
Returns AssertionError
- Defined in assert/assertionError.ts:557
- Defined in assert/assertionError.ts:679
AssertionFailure(message?: string): Error
Static
Parameters
- Optionalmessage: string
Returns Error
- Defined in assert/assertionError.ts:557
- Defined in assert/assertionError.ts:679

Index

Properties

actual? expected? fullStack innerException message name operator? orgValues? props? showDiff? stack? stackTraceLimit

Methods

captureStackTrace prepareStackTrace toJSON

Properties

`Optional`actual

actual?: any

The actual value that was seen. Changed to Mutable (from readonly) for backward compatibility in 0.1.6, but should be treated as read-only

Since

0.1.5

`Optional`expected

expected?: any

The value that was expected Changed to Mutable (from readonly) for backward compatibility in 0.1.6, but should be treated as read-only

Since

0.1.5

`Static`fullStack

fullStack: () => string

Gets the full stack trace of the error, this will show all of the internal calls that lead to the error being thrown. Useful for debugging as generally the stack trace will only show the location where the error was thrown.

Type Declaration

- (): string
- Returns string
  The full stack trace as a string.

`Static`innerException

innerException: () => Error

The error that caused this error to be thrown.

message

message: string

name

name: string

`Optional`operator

operator?: string

The operator used in the assertion Changed to Mutable (from readonly) for backward compatibility in 0.1.6, but should be treated as read-only

Since

0.1.5

`Optional` `Readonly`orgValues

orgValues?: IAssertionErrorOrgValues

The original values of the properties before any modifications were made for backward compatibility with older versions of frameworks (like mocha). This allows for referencing the original values if needed, while still allowing the properties to be modified for compatibility reasons. This property and its properties are readonly to prevent modification and will only be set if any of the original properties (actual, expected, operator, showDiff) are present on the error object AND the values are modified to be different than the original values. If the original values are the same as the modified values, then this property will not be set. While the actual and expected properties are commonly also in the props object, these top-level properties are mutable and therefore it is possible that some frameworks may modify these properties directly on the error object.

Since

0.1.6

`Optional` `Readonly`props

props?: T

Additional properties that are included in the error.

`Optional`showDiff

showDiff?: boolean

Indicates whether to show the difference between expected and actual values in the error message. Changed to Mutable (from readonly) for backward compatibility in 0.1.6, but should be treated as read-only

Since

0.1.5

`Optional`stack

stack?: string

`Static`stackTraceLimit

stackTraceLimit: number

The Error.stackTraceLimit property specifies the number of stack frames collected by a stack trace (whether generated by new Error().stack or Error.captureStackTrace(obj)).

The default value is 10 but may be set to any valid JavaScript number. Changes will affect any stack trace captured after the value has been changed.

If set to a non-number value, or set to a negative number, stack traces will not capture any frames.

Methods

`Static`captureStackTrace

captureStackTrace(targetObject: object, constructorOpt?: Function): void
Creates a .stack property on targetObject, which when accessed returns a string representing the location in the code at which Error.captureStackTrace() was called.
```
const myObject = {};
Error.captureStackTrace(myObject);
myObject.stack;  // Similar to `new Error().stack`
```
The first line of the trace will be prefixed with ${myObject.name}: ${myObject.message}.

The optional constructorOpt argument accepts a function. If given, all frames above constructorOpt, including constructorOpt, will be omitted from the generated stack trace.

The constructorOpt argument is useful for hiding implementation details of error generation from the user. For instance:
```
function a() {
  b();
}

function b() {
  c();
}

function c() {
  // Create an error without stack trace to avoid calculating the stack trace twice.
  const { stackTraceLimit } = Error;
  Error.stackTraceLimit = 0;
  const error = new Error();
  Error.stackTraceLimit = stackTraceLimit;

  // Capture the stack trace above function b
  Error.captureStackTrace(error, b); // Neither function c, nor b is included in the stack trace
  throw error;
}

a();
```
Parameters
- targetObject: object
- OptionalconstructorOpt: Function
Returns void
- Defined in ../../common/temp/node_modules/@types/node/globals.d.ts:51

`Static`prepareStackTrace

prepareStackTrace(err: Error, stackTraces: CallSite[]): any
Parameters
- err: Error
- stackTraces: CallSite[]
Returns any
See
https://v8.dev/docs/stack-trace-api#customizing-stack-traces
- Defined in ../../common/temp/node_modules/@types/node/globals.d.ts:55

`Static`toJSON

toJSON(stack?: boolean): any
Converts the error to a JSON object.
Parameters
- Optionalstack: boolean
  Whether to include the stack trace in the JSON object.
Returns any
A JSON representation of the error.
- Defined in assert/assertionError.ts:195

Class AssertionFailure<T>

Param: message

Param: props

Param: stackStart

Returns

Example

Type Parameters

Type Parameters

Parameters

Returns AssertionFailure<T>

Example

Type Parameters

Parameters

Returns AssertionFailure<T>

Example

Type Parameters

Parameters

Returns AssertionError<T>

Type Parameters

Parameters

Returns AssertionError<T>

Parameters

Returns AssertionError

Parameters

Returns Error

Index

Properties

Methods

Properties

Optionalactual

Since

Optionalexpected

Since

StaticfullStack

Type Declaration

Returns string

StaticinnerException

message

name

Optionaloperator

Since

Optional ReadonlyorgValues

Since

Optional Readonlyprops

OptionalshowDiff

Since

Optionalstack

StaticstackTraceLimit

Methods

StaticcaptureStackTrace

Parameters

Returns void

StaticprepareStackTrace

Parameters

Returns any

See

StatictoJSON

Parameters

Returns any

Settings

On This Page

`Optional`actual

`Optional`expected

`Static`fullStack

`Static`innerException

`Optional`operator

`Optional` `Readonly`orgValues

`Optional` `Readonly`props

`Optional`showDiff

`Optional`stack

`Static`stackTraceLimit

`Static`captureStackTrace

`Static`prepareStackTrace

`Static`toJSON