Re: How do I unit test a Dispose method ?

Sorry - hit send too early:

It depends.

If its Dispose() method has been called (its owner has requested early
release of its resources), then it is required to call Dispose() on all of
its IDisposable objects.

However, if its Dispose() method is not called then cleanup is ultimately
initiated by the GC through the Finalization Queue. As the order of
finalization is not guaranteed, the object must not call Dispose() on any
of its IDisposable objects.

This only applies to objects that it owns. Otherwise if it dispose of a
reference that has been passed to it (say through injection) then it may be
closing an object that is still required elsewhere.


On 3 February 2014 14:33, David Burstin <[email protected]> wrote:

> It depends.
>
> If its Dispose() method has been called (its owner has requested early
> release of its resources), then it is required to call Dispose() on all of
> its IDisposable objects.
>
> However, if its Dispose() method is not called then cleanup is ultimately
> initiated by the GC through the Finalization Queue. As the order of
> finalization is not guaranteed, the object must not call Dispose() on any
> of its IDisposable objects.
>
>
> On 3 February 2014 14:28, Amir Kolsky <[email protected]>wrote:
>
>>
>>
>>  Should an IDisposable object call Dispose on the IDisposable objects
>> that it holds?
>>
>>
>>
>> *From:* [email protected] [mailto:
>> [email protected]] *On Behalf Of *David Burstin
>> *Sent:* Sunday, February 2, 2014 7:25 PM
>> *To:* [email protected]
>>
>> *Subject:* Re: [TDD] How do I unit test a Dispose method ?
>>
>>
>>
>>
>>
>> Hi all. Long time listener, first time caller :)
>>
>>
>>
>> I've just finished a blog post called Growing IDisposable Guided By Tests<http://www.ambersolutions.com.au/dburstin/index.php/2014/02/03/growing-idisposable-guided-by-tests/>
>>
>>
>>
>> As IDisposable is primarily about managing internal resources, I agree
>> with Amir that the best approach is to subclass, which allows us to spy on
>> those resources. But I would not inject the resources to spy on as only the
>> owner of the resource is responsible for its disposal - in this case the
>> owner would be the test, not the SUT.
>>
>>
>>
>>
>>
>>
>>
>> On 24 January 2014 19:28, Donaldson, John <[email protected]>
>> wrote:
>>
>>
>>
>> .a. Yes, you are right it's an implementation detail.
>> Would another way make things easier?
>>
>> For example, separate the storing of the password from the Connection.
>> You might delegate to the PasswordStore to hold and remove passwords.
>> Then you just need to show that:
>> - the PasswordStore is wired up to the Connection
>> - the PasswordStore does what you want.
>>
>> John D.
>>
>>
>>
>> -----Original Message-----
>> From: [email protected] [mailto:
>> [email protected]] On Behalf Of Amir Kolsky
>> Sent: 24 January 2014 03:07
>> To: [email protected]
>> Subject: RE: [TDD] How do I unit test a Dispose method ?
>>
>> Here's another way of thinking about this - Whether a member is
>> IDisposable or not is really an implementation issue (as which members
>> comprise an object is private).
>> So the general question here is how do we get an object to identify all
>> of its IDisposable private methods and invoke Dispose on them in its
>> Dispose.
>> There are several ways I can think of doing this, all of which are sort
>> of terrible, but then, we're dealing with a true implementation specific
>> problem.
>>
>> The underlying technique in all cases is going to be the injection of two
>> more members which are IDisposable mocks.
>>
>> We can try to .emit code at runtime that will add these mocks to the UUT,
>> but - ugh!
>> Partial classes could work, but then we'd have to mark the original as
>> partial, so - ugh!
>> The easiest is to subclass the original class and have the (mock)
>> subclass have two (mock) members whose Dispose() must be called. The
>> implementation would, naturally, have to use reflection to find all members
>> and Dispose() of them properly, but that's what we want to see anyway.
>>
>> The price to pay is that the class cannot be sealed, but that is really
>> not a problem as only API classes should be sealed anyway and if you class
>> serves both as an API and it actually does anything, shame on you :)
>>
>> .a.
>>
>> From: [email protected]<mailto:
>> [email protected]> [mailto:
>> [email protected]] On Behalf Of Roy Osherove
>> Sent: Thursday, January 23, 2014 4:18 AM
>> To: testdrivendevelopment
>> Subject: Re: [TDD] How do I unit test a Dispose method ?
>>
>> Isn't there already an IDisposable interface? which means you can easily
>> create an IDisposable MOCK object and check if dispose was called on it.
>> all you would do it then have casted IDisposable in the class level that
>> you would access from the dispose method.
>>
>> public Connection(SecureString password) { IDisposable
>> _myDisposablePassword;
>> _myPassword = password.Copy(); // creates a clone of the password which
>> needs to be disposed _myDisposablePassword = _myPassword; } public void
>> Dispose() {
>> _myDisposablePassword.Dispose(); // releases any resources it holds } On
>> Thu, Jan 23, 2014 at 12:06 PM, Gishu Pillai <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>> public Connection(SecureString password) {
>> _myPassword = password.Copy(); // creates a clone of the password which
>> needs to be disposed } public void Dispose() {
>> _myPassword.Dispose(); // releases any resources it holds }
>>
>> SecureString is a .Net framework type. I could wrap it in an adapter to
>> ease testing...but doesn't solve the general problem. Wrapping all member
>> disposable type with interfaces is going to be tedious.
>> It seems this is a better fit for Static code analysis.
>> Gishu
>>
>> --
>> Thanks,
>>
>> Roy Osherove
>>
>> - @RoyOsherove<https://twitter.com/RoyOsherove>
>> - Read my new book Notes to a Software Team Leader<
>> http://TeamLeadSkills.com>
>> - My blog for team leaders: http://5Whys.com
>> - +47-96-90-22-15<tel:%2B47-96-90-22-15 <%2B47-96-90-22-15>> (Oslo Time)
>>
>> [Non-text portions of this message have been removed]
>>
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