MockFunctionContext

[<Interface>]
type MockFunctionContext<'F> =
    abstract member calls: MockFunctionCall<'F,obj,obj array> array
    static member Create (calls: MockFunctionCall<'F,obj,obj array> array, callCount: unit -> float, mockImplementation: 'F -> unit, mockImplementationOnce: Action<'F,float option>, resetCalls: unit -> unit, restore: unit -> unit) : MockFunctionContext<'F>
    abstract member callCount () : float
    abstract member mockImplementation (implementation: 'F) : unit
    abstract member mockImplementationOnce (implementation: 'F, ?onCall: float) : unit
    abstract member resetCalls () : unit
    abstract member restore () : unit


Assembly	`Xantham.Fable.Node`
Attributes	`[<Interface>]`

The MockFunctionContext class is used to inspect or manipulate the behavior of mocks created via the MockTracker APIs.

@since v19.1.0, v18.13.0

Properties

abstract member calls: MockFunctionCall<'F,obj,obj array> array

A getter that returns a copy of the internal array used to track calls to the mock. Each entry in the array is an object with the following properties.

@since v19.1.0, v18.13.0

Methods

static member Create (calls: MockFunctionCall<'F,obj,obj array> array, callCount: unit -> float, mockImplementation: 'F -> unit, mockImplementationOnce: Action<'F,float option>, resetCalls: unit -> unit, restore: unit -> unit) : MockFunctionContext<'F>

abstract member callCount () : float

This function returns the number of times that this mock has been invoked. This function is more efficient than checking ctx.calls.length because ctx.calls is a getter that creates a copy of the internal call tracking array.

@since v19.1.0, v18.13.0

Returns. The number of times that this mock has been invoked.

abstract member mockImplementation (implementation: 'F) : unit

This function is used to change the behavior of an existing mock.

The following example creates a mock function using t.mock.fn(), calls the mock function, and then changes the mock implementation to a different function.

test('changes a mock behavior', (t) => {
let cnt = 0;

function addOne() {
cnt++;
return cnt;
}

function addTwo() {
cnt += 2;
return cnt;
}

const fn = t.mock.fn(addOne);

assert.strictEqual(fn(), 1);
fn.mock.mockImplementation(addTwo);
assert.strictEqual(fn(), 3);
assert.strictEqual(fn(), 5);
});

@since v19.1.0, v18.13.0

Parameter
`implementation`	The function to be used as the mock's new implementation.

abstract member mockImplementationOnce (implementation: 'F, ?onCall: float) : unit

This function is used to change the behavior of an existing mock for a single invocation. Once invocation onCall has occurred, the mock will revert to whatever behavior it would have used had mockImplementationOnce() not been called.

The following example creates a mock function using t.mock.fn(), calls the mock function, changes the mock implementation to a different function for the next invocation, and then resumes its previous behavior.

test('changes a mock behavior once', (t) => {
let cnt = 0;

function addOne() {
cnt++;
return cnt;
}

function addTwo() {
cnt += 2;
return cnt;
}

const fn = t.mock.fn(addOne);

assert.strictEqual(fn(), 1);
fn.mock.mockImplementationOnce(addTwo);
assert.strictEqual(fn(), 3);
assert.strictEqual(fn(), 4);
});

@since v19.1.0, v18.13.0

Parameter
`implementation`	The function to be used as the mock's implementation for the invocation number specified by `onCall`.
`onCall`	The invocation number that will use `implementation`. If the specified invocation has already occurred then an exception is thrown.

abstract member resetCalls () : unit

Resets the call history of the mock function.

@since v19.3.0, v18.13.0

abstract member restore () : unit

Resets the implementation of the mock function to its original behavior. The mock can still be used after calling this function.

@since v19.1.0, v18.13.0