Add possibility to enqueue/append requests with server.use instead of only being able to append

[MartinJaskullaAccenture]

This is how I would like to write my unit tests (I wrapped server.use in the mockOnce utility function):

mockOnce<MyInterface1>("get", myMockData1);
mockOnce<MyInterface2>("get", myMockData2);
clickAddToBasket()

mockOnce<MyInterface3>("get", myMockData3);
clickGoToCheckout()

expect(hasUncalledMockOnceCalls()).toBe(false);

By reading this I would assume that clickAddToBasket triggers 2 api calls in the order they appear in the test. However the first api call would return myMockData2, because msw essentially uses a stack instead of a queue.

It would be nice if server.use would accept options, which allow me to enqueue/append my requests instead of appending them (In theory I would like to enqueue the server.use calls, but keep the original handlers passed to setupServer last in the queue).

If this is not feasible, then the feature request Get currently registered handlers would also help with my use case. Then it would be easy to get the current handlers in mockOnce where I could do my custom enqueueing.

[kettanaito]

Hey, @MartinJaskullaAccenture.

Looks like you're looking for res.once(). Once a handler uses a mocked response composed via res.once(), that handler gets "deactivated" and is ignored for the rest of the response resolution cycle. You can reset its ignored state via .restoreHandlers at any point.

[MartinJaskullaAccenture]

Not sure I am following. In my mockOnce function I am using server.use(rest.get((req, res) => res.once)), but server.use prepends the handlers, but I want to append them instead.

[MartinJaskullaAccenture]

Without my util function

server.use(rest.get("*", (req, res, ctx) => res.once(ctx.status(200), ctx.json(myMockData1), ctx.delay(150))))
server.use(rest.get("*", (req, res, ctx) => res.once(ctx.status(200), ctx.json(myMockData2), ctx.delay(150))))
clickAddToBasket()

server.use(rest.get("*", (req, res, ctx) => res.once(ctx.status(200), ctx.json(myMockData3), ctx.delay(150))))
clickGoToCheckout()

expect(hasUncalledMockOnceCalls()).toBe(false);

Ah okay I got it.

What I need to do is:

server.use(
  rest.get(),
  rest.get()
)

instead of

server.use(rest.get())
server.use(rest.get())

Can't use my concise util function I guess

[kettanaito]

I'm afraid the internal order of handlers shouldn't be controlled by the public API. If you append a handler, it has a chance of never taking effect because there may be a preceding handler defined earlier which will match a request. With server.use() you declare an intention to customize previously declare behavior. That's why internally it prepends handlers.

If you want to abstract code, abstract the handler part, not the server.use

server.use(
  mockOnce(...),
  mockOnce(...)
)