Rails Mocks

Rails Mocks Makes stubbing in your Rails application from an external resource easier.

The gem adds middleware to rails to execute stubs before make any query. It based on rspec-mocks library.

Install

group :test do
  gem "rails_mocks", "~> 0.0.1"
end

Available functionality

What we can execute before make request on the rails side:

# Instead of User we can use any rails constant
# It can be name of service, model, controller, etc
allow(User).to receive(:name)
allow_any_instance_of(User).to receive(:email).and_return("user@email.com")
allow(Book).to receive(:title).and_return("The Book")
allow(OrderService).to receive(:new).with(sum: 543).and_return(double(total: 543, id: 1))
allow(SumService).to receive(:new).with(double(a: 1, b: 5, c: 4)).and_return(double(sum: 10))

Usage

To stub something from external resource we should set header RAILS_MOCKS in the http request with the syntax below.

req.headers["RAILS_MOCKS"] = JSON.stringify([
    {
        allow: "User",
        receive: "name"
    },

    {
        allow_any_instance_of: "User",
        receive: "name",
        and_return: { body: "user@email.com" }
    },

    {
        allow: "Book",
        receive: "title",
        and_return: { body: "The Book" }
    },

    {
        allow: "OrderService",
        receive: "new",
        with: { body: { sum: 543 } },
        and_return: { body: { total: 543, id: 1 }, double: true }
    },

    {
        allow: "SumService",
        receive: "new",
        with: { body: { a: 1, b: 5, c: 4 }, double: true },
        and_return: { body: { sum: 10 }, double: true }
    }
])

Cypress

Here the example how to stub Stripe from cypress:

describe("when do refund", function() {
    beforeEach(function () {
        const chargeID = "frefef-43referf-43fref"

        cy.intercept("*", req => {
            req.headers["RAILS_MOCKS"] = JSON.stringify([
                {
                    allow: "Stripe::Refund",
                    receive: "create",
                    with: { body: { charge: chargeID }},
                    and_return: { body: { source: chargeID, status: "refunded" }, double: true}
                }
            ])
        })
    })

    it("then we click on the button and make refund",function() {

    })
})

We can use cy.intercept to modify headers of any request from the front-end application. But if we want to make stub when do cy.request we should set headers in the cy.request source:

cy.request({
    method: "POST",
    headers: {
      RAILS_MOCKS: JSON.stringify([
        {
          allow: "User",
          receive: "create"
        }
      ])
    },
    url: "/users",
    body: body
  })