如何用Jasmine2测试链式Knex方法（/ promises）？

Question

How can I test chained Knex methods with Jasmine2?

---

I have the following class and spec:

Task class

class Task {
    // ...
    findBy(field, value) {
        return this.Knex(this.tableName).where(field, value)
    }
    // ...
}

Task spec

// ...
beforeEach(() => {
    task = new Task()

    spyOn(task, 'Knex').and.returnValue(Q.when({}))
    spyOn(task.Knex, 'where').and.returnValue(Q.when({})) // <<< Wrong (where() isn't part of Knex anymore)
})

it('should expose findBy()', () => {
    let field = 'id'
      , value = 1

    task.findBy(field, value)
    expect(task.Knex).toHaveBeenCalledWith(task.tableName)
    expect(task.Knex.where).toHaveBeenCalledWith(field, value)
})
// ...

The error message I get is:

TypeError: this.Knex(...).where is not a function

Answer 1

There error was the return from the first spyOn() . The return is a promise without having where() as part of it.

This solves the problem (but lost the promise return from the first spyOn()

beforeEach(() => {
    task = new Task()

    knexRes = (spyOn(task, 'Knex').and.returnValue(({
        where: function() {}
    })))()

    spyOn(knexRes, 'where').and.returnValue(Q.when({}))
})

it('should expose findBy()', () => {
    let field = 'id'
      , value = 1

    task.findBy(field, value)
    expect(task.Knex).toHaveBeenCalledWith(task.tableName)
    expect(knexRes.where).toHaveBeenCalledWith(field, value)
})