angular-docs-cn/modules/angular2/test/change_detection/pipes/async_pipe_spec.js

import {ddescribe, describe, it, iit, xit, expect, beforeEach, afterEach,
  AsyncTestCompleter, inject, proxy, SpyObject} from 'angular2/test_lib';
import {IMPLEMENTS} from 'angular2/src/facade/lang';

import {AsyncPipe} from 'angular2/src/change_detection/pipes/async_pipe';
import {NO_CHANGE} from 'angular2/src/change_detection/pipes/pipe';
import {ChangeDetectorRef} from 'angular2/src/change_detection/change_detector_ref';
import {EventEmitter, Observable, ObservableWrapper, PromiseWrapper} from 'angular2/src/facade/async';

export function main() {
  describe("AsyncPipe", () => {
    var emitter;
    var pipe;
    var ref;
    var message = new Object();

    beforeEach(() => {
      emitter = new EventEmitter();
      ref = new SpyChangeDetectorRef();
      pipe = new AsyncPipe(ref);
    });

    describe("supports", () => {
      it("should support observables", () => {
        expect(pipe.supports(emitter)).toBe(true);
      });

      it("should not support other objects", () => {
        expect(pipe.supports("string")).toBe(false);
        expect(pipe.supports(null)).toBe(false);
      });
    });

    describe("transform", () => {
      it("should return null when subscribing to an observable", () => {
        expect(pipe.transform(emitter)).toBe(null);
      });

      it("should return the latest available value", inject([AsyncTestCompleter], (async) => {
        pipe.transform(emitter);

        ObservableWrapper.callNext(emitter, message);

        PromiseWrapper.setTimeout(() => {
          expect(pipe.transform(emitter)).toEqual(message);
          async.done();
        }, 0)
      }));

      it("should return NO_CHANGE when nothing has changed since the last call",
          inject([AsyncTestCompleter], (async) => {
        pipe.transform(emitter);
        ObservableWrapper.callNext(emitter, message);

        PromiseWrapper.setTimeout(() => {
          pipe.transform(emitter);
          expect(pipe.transform(emitter)).toBe(NO_CHANGE);
          async.done();
        }, 0)
      }));

      it("should dispose of the existing subscription when subscribing to a new observable",
          inject([AsyncTestCompleter], (async) => {
        pipe.transform(emitter);

        var newEmitter = new EventEmitter();
        expect(pipe.transform(newEmitter)).toBe(null);

        // this should not affect the pipe, so it should return NO_CHANGE
        ObservableWrapper.callNext(emitter, message);

        PromiseWrapper.setTimeout(() => {
          expect(pipe.transform(newEmitter)).toBe(NO_CHANGE);
          async.done();
        }, 0)
      }));

      it("should request a change detection check upon receiving a new value",
          inject([AsyncTestCompleter], (async) => {
        pipe.transform(emitter);
        ObservableWrapper.callNext(emitter, message);

        PromiseWrapper.setTimeout(() => {
          expect(ref.spy('requestCheck')).toHaveBeenCalled();
          async.done();
        }, 0)
      }));
    });

    describe("onDestroy", () => {
      it("should do nothing when no subscription", () => {
        pipe.onDestroy();
      });

      it("should dispose of the existing subscription", inject([AsyncTestCompleter], (async) => {
        pipe.transform(emitter);
        pipe.onDestroy();

        ObservableWrapper.callNext(emitter, message);

        PromiseWrapper.setTimeout(() => {
          expect(pipe.transform(emitter)).toBe(null);
          async.done();
        }, 0)
      }));
    });
  });
}

@proxy
@IMPLEMENTS(ChangeDetectorRef)
class SpyChangeDetectorRef extends SpyObject {
  constructor(){super(ChangeDetectorRef);}
  noSuchMethod(m){return super.noSuchMethod(m)}
}