Model Factoy proposal

case.model.js

define([
  'common/modules/models'
], function (models) {
  'use strict';

  CaseModel.$inject = ['CaseInstance', 'ModelFactory'];

  models.factory('Case', CaseModel);

  function CaseModel (CaseInstance, ModelFactory) {
    var Case = ModelFactory({
      entity: 'Case',
      instance: CaseInstance
      // api: CaseApi <--- pass instead of "entity" if you want some custom api
    });

    // no need to define Case.all

    // in case you want to define some custom method for Case models:
    Case.findExpired = function () {
      // ...
    };

    return Case;
  }
});

model-factory.service.js

define([
  'common/modules/services'
], function (services) {
  'use strict';

  ModelFactory.$inject = ['APIFactory', 'instance', 'Model'];

  services.factory('ModelFactory', ModelFactory);

  function ModelFactory (APIFactory, genericInstance, Model) {
    return function (modelConfiguration) {
      var api = modelConfiguration.api || APIFactory(modelConfiguration.entity);
      var instance = modelConfiguration.instance || genericInstance;

      return Model.extend({
        all: all
      });

      function all (filters, pagination, etc) {
        api.all(filters, pagination, etc)
          .then(function (response) {
            response.list = response.list.map(function (entry) {
              return instance.init(entry, true);
            });

            return response;
          });
      }
    }
  }
});

For testing the Case model we'd just check if it passes the right parameters to the ModelFactory and test any custom methods.