[OpenJDK 2D-Dev] Review Request for JDK-7107905: ColorModel subclasses are missing hashCode() or equals() or both methods

[Jayathirth D V]

Hi Phil & Jim,

Thanks for your inputs.

I have verified with previous iteration of the changes and both #1 and #4 fail from the time we have introduced the change in how we calculate "nBits" in ColorModel.
 
-        nBits = bits.clone();
+        /*
+         * We need significant bits value only for the length
+         * of number of components, so we truncate remaining part.
+         * It also helps in hashCode calculation since bits[] can contain
+         * different values after the length of number of components between
+         * two ColorModels.
+         */
+        nBits = Arrays.copyOf(bits, numComponents);

#2 and #3 would fail from the time we have removed equals() and hashCode() methods from ColorModel, to follow identity-as-equals verification.
Collectively all of them are failing right now as we have both the changes at http://cr.openjdk.java.net/~jdv/7107905/webrev.15/ .

Thanks,
Jay

-----Original Message-----
From: Phil Race 
Sent: Tuesday, January 31, 2017 5:27 AM
To: Jim Graham; Jayathirth D V; 2d-dev at openjdk.java.net
Subject: Re: [OpenJDK 2D-Dev] Review Request for JDK-7107905: ColorModel subclasses are missing hashCode() or equals() or both methods

Sounds like we should at least try to get the tests updated so they only test what the spec. says.
Although it does indicate that there is at least a chance that application code might also fail due to similar assumptions.
Does #1 not fail with the previous iteration of this change too ?

-phil.

On 01/30/2017 01:40 PM, Jim Graham wrote:
> Hmmm.  Sounds like the test cases were written based on bugs in the 
> implementation.  I'm not sure what the best tactic is here for the 
> short term for getting this in, but many of these changes should 
> eventually be considered bugs in the tests.  Is it acceptable to break 
> API tests like this at the last minute even if the tests are at fault?  
> Phil?
>
> Notes on specific instances below...
>
> On 1/30/17 2:22 AM, Jayathirth D V wrote:
>> Hi Phil,
>>
>>     1)api/java_awt/Image/ColorModel/index.html#Constructor: Failed. 
>> test cases: 4; passed: 3; failed: 1; first test case failure: 
>> ColorModel2001
>>
>>     This test fails because getComponentSize() returned an array with 
>> length 3 but it expects the length to be 4. In the test case they
>> have bits per component array     of length 4 like {8, 8, 8, 8}. But 
>> in the test case wherever they are passing "has Alpha" as "false" we 
>> omit the alpha component bit. This is because of tighter check     
>> that we have in ColorModel class as "nBits = Arrays.copyOf(bits, 
>> numComponents);" . "numComponents" will be 3 if hasAlpha is false.
>
> This is a bug in the test then, especially if the size of our array 
> matches the return value of getNumComponents.
>
>>     2)api/java_awt/Image/ColorModel/index.html#Equals: Failed. test
>> cases: 3; passed: 2; failed: 1; first test case failure: 
>> ColorModel0004
>>
>>     Here they check for equality between 2 ColorModel objects having 
>> same values, but it fails because now we are using identity-as-equals 
>> check in ColorModel.
>
> How do they accomplish this when the CM class is abstract?  Do they 
> create a relatively empty subclass and instantiate that?
>
> The documentation for the equals() method does not document the 
> conditions under which it returns true, it uses a vague concept of 
> "equals this ColorModel".  I don't see how they could test anything 
> given that documentation.
>
>>     3)api/java_awt/Image/ColorModel/index.html#HashCode: Failed. test
>> cases: 2; passed: 1; failed: 1; first test case failure: 
>> ColorModel2006
>>
>>     Here they check for hashCode equality between 2 ColorModel 
>> objects having same values, but it fails since we don't have hashCode
>> check in ColorModel and it     will be different between 2 Objects.
>
> Same as above, there are no promises documented.
>
>>     4)api/java_awt/Image/ComponentColorModel/index.html#ConstructorTesttestCase1: 
>> Failed. test cases: 2; passed: 1; failed: 1; first test case failure: 
>> testCase1
>>
>>     Throws "java.lang.ArrayIndexOutOfBoundsException: 3". This is 
>> also happening because of same reason as why the first JCK test is
>> failing. We omit alpha bit if     hasAlpha is false but JCK test 
>> tries to call getComponentSize() with index 3 which throws 
>> ArrayIndexOutOfBoundsException.
>
> Same assessment as #1 above...
>
> Again, while these are my recommendations about the correctness of 
> these tests, the question remains whether we want to introduce a 
> change at this point in the release cycle that will essentially 
> invalidate a number of tests that have been working for several 
> releases already.  I'll leave that tactic issue to Phil...
>
>                 ...jim
>