Add a built in default value for MediaType in NullPointerTester (and related)

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It would be nice if Guava could configure the NullPointerTester with a default 
instance for the MediaType type so we don't have to configure it manually in 
our tests. 

MediaType.ANY_TYPE would be fine.

Original issue reported on code.google.com by matt.nat...@gmail.com on 14 Feb 2014 at 9:59

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Original comment by kak@google.com on 18 Feb 2014 at 3:09

• Added labels: Package-Testing, Type-Enhancement

[GoogleCodeExporter]

Perhaps NullPointerTester (or one of the classes it uses) should be smart 
enough to look for instances of a class in that class's static final fields.

If we instead handle MediaType specifically, I have some reservations about 
whether we want to go down the road of adding default values for our types when 
we don't personally need them. But I don't feel that strongly, and given that 
this is the first request we've gotten that I can recall, I'm not too concerned.

(Also, Greg points out that a direct usage of MediaType would introduce a 
testing->net dependency. Kevin and Christian suggest that we won't ever want a 
net->testing dep, and I agree: There's no concern about circularity.)

Original comment by cpov...@google.com on 18 Feb 2014 at 6:00

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Ben, is this something that you've considered in the past...?

"Perhaps NullPointerTester (or one of the classes it uses) should be smart 
enough to look for instances of a class in that class's static final fields."

Original comment by cpov...@google.com on 18 Feb 2014 at 6:02

[GoogleCodeExporter]

There seems to be a few different options. Ordering from the most specific to 
more generic:

1. Just add default value for MediaType.

2. ArbitraryInstances can look for public-static-final fields of type Foo in 
class Foo.

3. Why stop there? ArbitraryInstances can also look for zero-arg static factory 
methods.

4. Why stop there? ArbitraryInstances also can look for public-static-final 
fields in a class called "Foos".

ArbitraryInstances already look for zero-arg public constructors. So it doesn't 
seem that out of line to expand the search to constants and factory methods. 
The use of "Foos" is a bit of strech. Although it seems pretty common that 
constants and factories live in a Foos class instead of the original Foo?

We probably need to get determinism right. Whichever field/factory we choose to 
use among multiple choices, we don't want the choice to change when the source 
code doesn't change. So picking the first from getDeclaredFields() or 
getDeclaredMethods() isn't ideal.

Sorting by field/method name possibly will suffice.

Original comment by be...@google.com on 18 Feb 2014 at 8:23

[GoogleCodeExporter]

We went with "2. ArbitraryInstances can look for public-static-final fields of 
type Foo in class Foo."

http://code.google.com/p/guava-libraries/source/detail?r=deff3845959d6be8b6eeb80
2d76b2b7637d1cc02

Original comment by cpov...@google.com on 3 Mar 2014 at 3:11

• Changed state: Fixed
• Added labels: Milestone-Release17

[GoogleCodeExporter]

This issue has been migrated to GitHub.

It can be found at https://github.com/google/guava/issues/<issue id>

Original comment by cgdecker@google.com on 1 Nov 2014 at 4:10

• Added labels: MigratedToGitHub

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Original comment by cgdecker@google.com on 3 Nov 2014 at 9:07

• Added labels: Restrict-AddIssueComment-Commit