[LLVMdev] Private headers and testing

[Chris Lattner]

On Jan 7, 2009, at 1:29 PM, Misha Brukman wrote:

> 2009/1/3 Chris Lattner <clattner at apple.com>
> On Jan 2, 2009, at 1:48 PM, Misha Brukman wrote:
>> 2009/1/2 Chris Lattner <clattner at apple.com>
>> On Jan 2, 2009, at 12:21 PM, Misha Brukman wrote:
>> Do you have a specific example of a unit test that would need  
>> these?  I really think these should stay private.
>>
>> Let's take lib/Transforms/Utils/CodeExtractor.cpp .  The public  
>> interface for it is in include/llvm/Transform/Utils/ 
>> FunctionUtils.h, with only the high-level API.
>>
>> If I want to test some corner-case (consider the number of code  
>> paths in that code), I have to strain to come up with some  
>> combination of a Function and input BasicBlocks that will fit all  
>> the conditions from the outset.  Or, I can just feed each  
>> individual method in the class exactly the corner cases I will want  
>> it to handle, and verify its output (or side effects) exactly, to  
>> make sure I pin-pointed the issue.
> Sure, ok.  But that is a public API, I'm specifically interested in  
> cases you need private API.
>
> I'm not sure I understand what you mean.  What I am saying is that I  
> want to expose the innards of CodeExtractor.cpp in a header file,  
> #include that in the unittest, and move the implementation out of an  
> anonymous namespace into llvm::transforms::utils, or  
> llvm::internal::transforms::utils, or similar, so it can be unit- 
> tested.  This is not about exposing the private API to end-users of  
> LLVM or even other LLVM libraries, just unittests.
>
> The public API, while useful to the end-user, is limiting when it  
> comes to unit-testing.  "Unit" in this case is a single method of  
> the actual implementation (i.e., a method of the CodeExtractor  
> class), not a single function call of the high-level exported public  
> API, which will exercise the entire class and its many methods.

I am pretty strongly against that.  Specifically for CodeExtractor,  
what benefit do you gain by doing this?

-Chris
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