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From Richard Liang <richard.lian...@gmail.com>
Subject Re: [Testing Convention] Keep tests small and fast
Date Fri, 31 Mar 2006 03:52:59 GMT
will pugh wrote:
> I'm not too familiar with the Harmony code yet, but since I've had a 
> bunch of experience on large projects I thought I'd toss my $.02 in here.
> 1)  When dealing with a project as large and with as much surface area 
> as a VM, your unit tests for the entire project will probably take 
> several hours to run.  The trade off for heavy coverage is totally 
> worth it, even if it takes a long time.  It does indeed mean you need 
> to manage it.
> 2)  We tended to manage this by breaking up unit tests into Build 
> Verification Tests(BVTs) and Developer Regression Tests(DRTs).  
> Developers would be required to run DRTs before checking in, and BVTs 
> would be run for every build (or with coninous integration, they would 
> be constantly running every few hours).
> 3)  In the largest projects I've been on DRTs would be broken up 
> further to be on a component level.  When you changed a component that 
> other components depended on, we tended to depend on the good sense of 
> the developer to run the DRTs for the related components (and depended 
> on the CI or daily build to catch the problems that slipped through 
> that net.)  We set a rule that DRTs for a given component could never 
> take longer than 10 minutes to run.
> Again, I'm sorry if this is irrelevent (since I'm not familiar enough 
> with the Harmony code), but this process was reasonably effective for 
> us.  The real pain ends up being how often changes in core code broke 
> downstream components, but failing tests are only a symptom (and early 
> warning system) for this.
> The problem is that for core components, it was often important for 
> the developers to run rather a rather long suite of tests before 
> checking in, simply because there were so many components using their 
> pieces.  We just bit that bullet.
>    --Will
> Richard Liang wrote:
>> Dears,
>> I notice that we put all the test code into one big test method (for 
>> example, 
>> org.apache.harmony.tests.java.util.jar.test_putLjava_lang_ObjectLjava_lang_Object).

>> This way we will lose some benefits of junit and even unit test:
>> 1. Test code cannot share configuration code through setUp and tearDown
>> 2. We have to add redundant code, such as, "Assert 1:", "Assert 2: 
>> ...." to make the test results more comprehensive
>> 3. It makes the test code more complex
>> Shall we just use small test cases?
>> You may want to read the description at: 
>> http://www.javaworld.com/javaworld/jw-12-2000/jw-1221-junit_p.html
>> *Keep tests small and fast*
>> Executing every test for the entire system shouldn't take hours. 
>> Indeed, developers will more consistently run tests that execute 
>> quickly. Without regularly running the full set of tests, it will be 
>> difficult to validate the entire system when changes are made. Errors 
>> will start to creep back in, and the benefits of unit testing will be 
>> lost. This means stress tests and load tests for single classes or 
>> small frameworks of classes shouldn't be run as part of the unit test 
>> suite; they should be executed separately.
>> Thanks a lot.
>> Richard Liang wrote:
>>> Dears,
>>> As I cannot find similar pages about testing convention, I just 
>>> create one with my rough ideas 
>>> http://wiki.apache.org/harmony/Testing_Convention, so that we can 
>>> document our decision timely & clearly.
>>> Geir Magnusson Jr wrote:
>>>> Leo Simons wrote:
>>>>> Gentlemen!
>>>>> On Mon, Mar 27, 2006 at 11:07:51AM +0200, mr A wrote:
>>>>>> On Monday 27 March 2006 10:14, mr B wrote:
>>>>>>> On 3/27/06, mr C wrote:
>>>>>>> [SNIP]
>>>>>>>> [SNIP]
>>>>>>>>> [SNIP]
>>>>>>>>>> On 1/1/2006, mr D wrote:
>>>>>>>>>>>>>>>>>>>>> [SNIP]
>>>>>>> Hmmm... Lemme support [SNIP]
>>>>>> Now let me support [SNIP].
>>>>> The ASF front page says
>>>>>   (...) "The Apache projects are characterized by a collaborative, 
>>>>> consensus
>>>>>   based development process, " (...)
>>>>> That's not just some boilerplate. Consensus is a useful thing.
>>>>> "How should we organize our tests?" has now been the subject of 
>>>>> debate for
>>>>> *months* around here, and every now and then much of the same 
>>>>> discussion is
>>>>> rehashed.
>>>> And we're making progress.  IMO, it really helped my thinking to 
>>>> distinguish formally between the implementation tests and the spec 
>>>> tests, because that *completely* helped me come to terms with the 
>>>> whole o.a.h.test.* issue.
>>>> I now clearly see where o.a.h.test.*.HashMapTest fits, and where 
>>>> java.util.HashMapTest fits.
>>>> I don't think our issues were that obvious before, at least to me.  
>>>> Now, I see clearly.
>>>>> I think it would be more productive to look for things to agree on 
>>>>> (such as,
>>>>> "we don't know, but we can find out", or "we have different ideas 
>>>>> on that,
>>>>> but there's room for both", or "this way of doing things is not 
>>>>> the best one
>>>>> but the stuff is still useful so let's thank the guy for his work 
>>>>> anyway")
>>>>> than to keep delving deeper and deeper into these kinds of 
>>>>> disagreements.
>>>>> Of course, the ASF front page doesn't say that "apache projects are
>>>>> characterized by a *productive* development process". Its just my 
>>>>> feeling that
>>>>> for a system as big as harmony we need to be *very* productive.
>>>> You don't think we're making progress through these discussions?
>>>>> Think about it. Is your time better spent convincing lots of other 
>>>>> people to do
>>>>> their testing differently, or is it better spent writing better 
>>>>> tests?
>>>> The issue isn't about convincing someone to do it differently, but 
>>>> understanding the full scope of problems, that we need to embrace 
>>>> both approaches, because they are apples and oranges, and we need 
>>>> both apples and oranges.  They aren't exclusionary.
>>>> geir

I'm sorry if my previous description make you confused :-)

What I mean is:  Keep each unit test method small. I do not want to make 
the whole unit test suite small.

Now we put all the test cases for one API method into one test method, 
this will make the test method more complex and hard to manage.

For example, I'd like to rewrite the following test method to **four** 
test methods instead of just **one**.

public void test_Ctor() {
    Ctor c = new Ctor(param1, param2, param3);

    assertEquals("Assert 1", param1, c.getParam1());
    assertEquals("Assert 2", param2, c.getParam2());
    assertEquals("Assert 3", param3, c.getParam3());

    Ctor c2 = new Ctor(null, param2, param3);

    assertNull("Assert 4", c2.getParam1());
    assertEquals("Assert 5", param2, c2.getParam2());
    assertEquals("Assert 6", param3, c3.getParam3());

    Ctor c3 = new Ctor(param1, null, param3);

    assertEquals("Assert 7", param1, c3.getParam1());
    assertNull("Assert 8", c3.getParam2());
    assertEquals("Assert 9", param3, c3.getParam3());

    Ctor c4 = new Ctor(param1, param2, null);

    assertEquals("Assert 10", param1, c4.getParam1());
    assertEquals("Assert 11", param2, c4.getParam2());
    assertNull("Assert 12", c4.getParam3());

Richard Liang
China Software Development Lab, IBM 

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