Testing cached m.request

model-excerpt.js

  var cache = [];

  model.latest = function() {
    makeRequest().then(replace); // If I put this on the function below, the tests still pass
    return function() {          // but when using mithril, I would get infinite requests
      return cache;
    };
  };

  function makeRequest() {
    return request({method: "GET", url: url, type: model});
  }

  function replace(list) {
    if (list.length) {
      cache = list;
    }
  }

test-excerpt.js

  describe("latest()", function() {
    it("returns an empty dataset, then populates and caches it", function() {
      var model = modelFactory("/someurl", []);
      var expected = [{id: 123}];

      var firstResponse    = mithril.deferred();
      var furtherResponses = mithril.deferred();

      requestStub
        .withArgs({method: "GET", url: "/someurl", type: model})
        .onFirstCall()
        .returns(firstResponse.promise);

      requestStub
        .withArgs({method: "GET", url: "/someurl", type: model})
        .returns(furtherResponses.promise);

      var latest = model.latest();
      assert.deepEqual(latest(), []);
      firstResponse.resolve(expected);
      assert.deepEqual(latest(), expected);
      furtherResponses.resolve([]);
      assert.deepEqual(latest(), expected);
    });