Re: Unit tests and parameter validation

Donald -

If a test passes in the wrong input and fails initially, I see 3 general
ways of getting the test to pass:

   1. Have your test look for the exception that will be thrown by the code
   2. Have your code validate the parameters to prevent an exception from
   being thrown
   3. Have you code substitute (handle in some other way) the bad parameter
   so that an exception is not thrown

Or is the assumption that my code should never call the method with a bad
parameter, hence I shouldn't have a test that tests with bad parameter?

Thanks.


On Tue, Oct 15, 2013 at 1:25 PM, Donaldson, John <[email protected]>wrote:

> **
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>  Eb, ****
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> I agree with Colin in principle, but wider than that I’d say, following
> Uncle Bob’s rule of “no code without a failing test” pretty well ensures
> you will have tests which supply incorrect inputs, if you want to handle
> those cases.****
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> John D.****
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> *From:* [email protected] [mailto:
> [email protected]] *On Behalf Of *Colin Vipurs
> *Sent:* 15 October 2013 18:52
> *To:* [email protected]
> *Subject:* Re: [TDD] Unit tests and parameter validation****
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> ****
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> If this is internal code only and the code calling it is also testing then
> I not only would I not test it but I'd remove all defensive code guards as
> well.  For example, a typical pattern would be:****
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> public void foo(SomeObject bar) {****
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>    if (bar == null) {****
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>    .....****
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>    }****
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> }****
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> Instead of catching the null and handling it, ensure all code calling it
> will never pass in null.  Cuts down on both test and production code.****
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> On Tue, Oct 15, 2013 at 5:03 PM, Eb <[email protected]> wrote:****
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> Hello everyone -****
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> I'm curious to know thoughts on writing tests that specify the behavior of
> a method when its inputs are incorrect.  Is this a common practice.  How
> about parameter validation in this case?  Having some healthy debate on it
> and wanted to get other insight.****
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> The context for this in a class/methods that are used within an internal
> application - this is not an API that will be publicly exposed to external
> consumers.****
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> Thanks.
> ****
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> -- ****
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> blog: http://eikonne.wordpress.com****
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> twitter: @eikonne****
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> ****
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> --
> Maybe she awoke to see the roommate's boyfriend swinging from the
> chandelier wearing a boar's head.
>
> Something which you, I, and everyone else would call "Tuesday", of course.
> ****
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> ****
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