instanceof(Date) fails for dates

[mattness]

Problem

Using should v0.6.3, the instanceof() method returns an incorrect result when called on a Date object and passed Date as its argument.

Expected behavior

Calling instanceof(Date) on a Date object should not throw an AssertionError.

Steps to reproduce

$ node
> require('should');
{ [Function: ok]
  AssertionError: 
   { [Function: AssertionError]
     super_: 
      { [Function: Error]
        captureStackTrace: [Function: captureStackTrace],
        stackTraceLimit: 10 } },
  fail: [Function: fail],
  ok: [Circular],
  equal: [Function: equal],
  notEqual: [Function: notEqual],
  deepEqual: [Function: deepEqual],
  notDeepEqual: [Function: notDeepEqual],
  strictEqual: [Function: strictEqual],
  notStrictEqual: [Function: notStrictEqual],
  throws: [Function],
  doesNotThrow: [Function],
  ifError: [Function],
  version: '0.6.3',
  exist: [Function],
  not: { exist: [Function] },
  Assertion: [Function: Assertion] }
> (new Date()).should.be.an.instanceof(Date);
AssertionError: expected 1335798857282 to be an instance of Date
    at Object.<anonymous> (/home/gollom/projects/surveycalc-node/node_modules/should/lib/should.js:355:10)
    at repl:1:27
    at REPLServer.eval (repl.js:80:21)
    at repl.js:190:20
    at REPLServer.eval (repl.js:87:5)
    at Interface.<anonymous> (repl.js:182:12)
    at Interface.emit (events.js:67:17)
    at Interface._onLine (readline.js:162:10)
    at Interface._line (readline.js:426:8)
    at Interface._ttyWrite (readline.js:603:14)

Work-around

$ node
> require('should')
{ [Function: ok]
  AssertionError: 
   { [Function: AssertionError]
     super_: 
      { [Function: Error]
        captureStackTrace: [Function: captureStackTrace],
        stackTraceLimit: 10 } },
  fail: [Function: fail],
  ok: [Circular],
  equal: [Function: equal],
  notEqual: [Function: notEqual],
  deepEqual: [Function: deepEqual],
  notDeepEqual: [Function: notDeepEqual],
  strictEqual: [Function: strictEqual],
  notStrictEqual: [Function: notStrictEqual],
  throws: [Function],
  doesNotThrow: [Function],
  ifError: [Function],
  version: '0.6.3',
  exist: [Function],
  not: { exist: [Function] },
  Assertion: [Function: Assertion] }
> (new Date() instanceof Date).should.be.true;
{ obj: true }

[TooTallNate]

This was probably my .valueOf() patch that broke it. I guess the solution is gonna be to revert that and only use valueOf() where explicitly needed (like equal()).

[kivikakk]

+1, this breaks commander.js's tests.

Even so, using it in equal(), true() and false() (which appear to be the candidates for use) still cause existing test cases to break on node ~0.6 (and I guess anything < 0.7.7).

[kivikakk]

V8 is doing my head in with this.

It's very tricky to distinguish whether or not a given object has been wrapped by Object in the newer versions or not; this.constructor still looks the same as it normally would, only typeof this returns "object" instead of e.g. "string" for a string.

So far the only way to "reliably" detect this appears to be a hack of checking that the constructor of the object appears to be a primitive type that might be wrapped, and then seeing if it was wrapped by looking at the typeof.

66 is a pull request with this change; I'm not suggesting you definitely should take this route, but at least we have all tests passing on node ~0.6 and 0.7.8 with this.

[leecookson]

Need to fix this...more packages will fail when upgrading to the latest version. Found a unit test in sentientwaffle/gift that worked with should.js 0.3.0), but fails with 0.6.3 I had to use the workaround for my fork.

[scott2449]

It is most definitely caused by the valueOf when should is defined and is still in all versions after 0.6.something

At the repl:

test = new Date() Wed Jul 18 2012 11:00:31 GMT-0400 (EDT) test instanceof Date true Object(test).valueOf() 1342623631108

it should be returning 'Date'

[TooTallNate]

+1

[Guuz]

I'm using the latest version of Should and Node.js and this is still an issue. Any updates?

[missinglink]

+1

[NatalieWolfe]

+1

[skovalyov]

+1

[tj]

+5

[fakewaffle]

+5

[TooTallNate]

I don't get it... if you guys want this feature, somebody write a patch.

IMO though you shouldn't be testing for instanceof ever though (except for in constructors). Consider a Date object returned from another VM context, it would fail this check.