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

Jim Graham james.graham at oracle.com
Tue Jan 31 22:34:03 UTC 2017

For an application to run into this same issue they'd have to expect getCompSizes() to return data for components that 
don't exist.  It's unlikely they would use that data if they really understand the objects.  While that would be odd, I 
guess I can see someone might be constructing all of their CM's from an array of 4 components regardless of the number 
of actual components and we'd be happily remembering the useless extra components and returning an array of 4 from 
getCompSizes().  As I said, they shouldn't really be reading and interpreting those extra components for any image 
processing, but I can imagine that they might do something like create a variant CM by calling the CompSizes() and 
copying them into a new array to construct a new CM with modifications.  They might just robotically always copy 4 
values without really checking how many are valid.  That's a stretch, and their code is weak.  I can conceive of how 
this might happen, but I really have no idea how likely it is...


On 1/30/17 3:56 PM, Phil Race wrote:
> 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

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