Add language tests for Issue 18628.

Add language tests for Issue 18628.

As suggested by @karlklose in https://codereview.chromium.org/513563002/
comments.

Improve testing documentation.

- add a README
- add a description by example of selectors to the "./tools/test.py -h"
  output
- update/add source comments

I had a hard time figuring out how to add and run the tests, mostly
because I tried to call them "*_test_1.dart" and "*_test_2.dart", but
language test files must have names of the form "*_test.dart".  So, I
added a README summarizing and referencing the relevant docs.

R=brianwilkerson@google.com, karlklose@google.com, jwren@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=39822

[Brian Wilkerson, 2014-08-31 15:06:51]

LGTM, but wait for Karl's review before committing

[karlklose, 2014-09-01 09:08:18]

LGTM with a few comments.

https://codereview.chromium.org/521773003/diff/1/tests/README
File tests/README (right):

https://codereview.chromium.org/521773003/diff/1/tests/README#newcode21
tests/README:21: Run a subset of the dartanalyzer tests:
I think these examples are to specific for this file.

In general, I think we should add examples to the wiki pages and only add a
pointer to these pages here.

https://codereview.chromium.org/521773003/diff/1/tests/README#newcode29
tests/README:29: --host-checked \
host-checked is only important for dart2js, where it is so slow that we usually
do not run it unless we changed the compiler itself.

https://codereview.chromium.org/521773003/diff/1/tests/README#newcode33
tests/README:33: language/issue18628
'language/issue18628' -> 'language'?

But, as said above, I would remove the examples.

https://codereview.chromium.org/521773003/diff/1/tests/language/issue18628_1_...
File tests/language/issue18628_1_test.dart (right):

https://codereview.chromium.org/521773003/diff/1/tests/language/issue18628_1_...
tests/language/issue18628_1_test.dart:12: T t = int; /// 01: static type warning
This warning is triggered, because the analyzer checks everything. In contrast,
dart2js does only compile (and type check) what it thinks it needs.

Currently, dart2js is not tested for warning, but this would fail if we did.

If you want to check that dart2js and the VM do a runtime check, you would have
to create an instance of C and assign to the field.

https://codereview.chromium.org/521773003/diff/1/tests/language/issue18628_1_...
tests/language/issue18628_1_test.dart:14: main(){}
Add a space between '()' and '{}'. Also below.

[Nathan Collins, 2014-09-03 00:14:19]

On 2014/09/01 09:08:18, karlklose wrote:
> LGTM with a few comments.
> 
> https://codereview.chromium.org/521773003/diff/1/tests/README
> File tests/README (right):
> 
> https://codereview.chromium.org/521773003/diff/1/tests/README#newcode21
> tests/README:21: Run a subset of the dartanalyzer tests:
> I think these examples are to specific for this file.
> 
> In general, I think we should add examples to the wiki pages and only add a
> pointer to these pages here.
> 
> https://codereview.chromium.org/521773003/diff/1/tests/README#newcode29
> tests/README:29: --host-checked \
> host-checked is only important for dart2js, where it is so slow that we
usually
> do not run it unless we changed the compiler itself.
> 
> https://codereview.chromium.org/521773003/diff/1/tests/README#newcode33
> tests/README:33: language/issue18628
> 'language/issue18628' -> 'language'?
> 
> But, as said above, I would remove the examples.
> 
>
https://codereview.chromium.org/521773003/diff/1/tests/language/issue18628_1_...
> File tests/language/issue18628_1_test.dart (right):
> 
>
https://codereview.chromium.org/521773003/diff/1/tests/language/issue18628_1_...
> tests/language/issue18628_1_test.dart:12: T t = int; /// 01: static type
warning
> This warning is triggered, because the analyzer checks everything. In
contrast,
> dart2js does only compile (and type check) what it thinks it needs.
> 
> Currently, dart2js is not tested for warning, but this would fail if we did.
> 
> If you want to check that dart2js and the VM do a runtime check, you would
have
> to create an instance of C and assign to the field.
> 
>
https://codereview.chromium.org/521773003/diff/1/tests/language/issue18628_1_...
> tests/language/issue18628_1_test.dart:14: main(){}
> Add a space between '()' and '{}'. Also below.

@karlklose: PTAL.

I moved the examples from the README to the wiki
(https://code.google.com/p/dart/source/detail?r=39786) and added code that uses
the suspect to classes to avoid having tree-shaking eliminate them.  I used the
suspect classes in ways that are consistent with their type annotations, so only
static checks are applicable for all systems (analyzer, VM, dart2js).

[karlklose, 2014-09-03 06:40:14]

On 2014/09/03 00:14:19, Nathan Collins wrote:
> On 2014/09/01 09:08:18, karlklose wrote:
> > LGTM with a few comments.
> > 
> > https://codereview.chromium.org/521773003/diff/1/tests/README
> > File tests/README (right):
> > 
> > https://codereview.chromium.org/521773003/diff/1/tests/README#newcode21
> > tests/README:21: Run a subset of the dartanalyzer tests:
> > I think these examples are to specific for this file.
> > 
> > In general, I think we should add examples to the wiki pages and only add a
> > pointer to these pages here.
> > 
> > https://codereview.chromium.org/521773003/diff/1/tests/README#newcode29
> > tests/README:29: --host-checked \
> > host-checked is only important for dart2js, where it is so slow that we
> usually
> > do not run it unless we changed the compiler itself.
> > 
> > https://codereview.chromium.org/521773003/diff/1/tests/README#newcode33
> > tests/README:33: language/issue18628
> > 'language/issue18628' -> 'language'?
> > 
> > But, as said above, I would remove the examples.
> > 
> >
>
https://codereview.chromium.org/521773003/diff/1/tests/language/issue18628_1_...
> > File tests/language/issue18628_1_test.dart (right):
> > 
> >
>
https://codereview.chromium.org/521773003/diff/1/tests/language/issue18628_1_...
> > tests/language/issue18628_1_test.dart:12: T t = int; /// 01: static type
> warning
> > This warning is triggered, because the analyzer checks everything. In
> contrast,
> > dart2js does only compile (and type check) what it thinks it needs.
> > 
> > Currently, dart2js is not tested for warning, but this would fail if we did.
> > 
> > If you want to check that dart2js and the VM do a runtime check, you would
> have
> > to create an instance of C and assign to the field.
> > 
> >
>
https://codereview.chromium.org/521773003/diff/1/tests/language/issue18628_1_...
> > tests/language/issue18628_1_test.dart:14: main(){}
> > Add a space between '()' and '{}'. Also below.
> 
> @karlklose: PTAL.
> 
> I moved the examples from the README to the wiki
> (https://code.google.com/p/dart/source/detail?r=39786) and added code that
uses
> the suspect to classes to avoid having tree-shaking eliminate them.  I used
the
> suspect classes in ways that are consistent with their type annotations, so
only
> static checks are applicable for all systems (analyzer, VM, dart2js).

For dart2js you only have to build everything before running tests if you want
to use "--use-sdk".

[karlklose, 2014-09-03 06:48:59]

LGTM.

To make reviewing patchsets easier, please either do not rebase between uploads
or upload a rebase patchset before uploading the changes that are done on the
rebased code.

In this CL, the delta of patchset 2 to patchset 1 seems to include changes to
the test infrastructure, but the whole patch does not, which can be confusing
during code review.

https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
File tests/language/issue18628_1_test.dart (right):

https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
tests/language/issue18628_1_test.dart:15: C<Type> c = new C<Type>();
You have to use the field 't' to force it to be compiled with tree-shaking.

https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
File tests/language/issue18628_2_test.dart (right):

https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
tests/language/issue18628_2_test.dart:14: class Y<U> extends X<U> {} /// 01:
static type warning
Add newlines between class and function declarations.

[Nathan Collins, 2014-09-03 18:49:49]

On 2014/09/03 06:48:59, karlklose wrote:
> LGTM.
> 
> To make reviewing patchsets easier, please either do not rebase between
uploads
> or upload a rebase patchset before uploading the changes that are done on the
> rebased code.
> 
> In this CL, the delta of patchset 2 to patchset 1 seems to include changes to
> the test infrastructure, but the whole patch does not, which can be confusing
> during code review.

Sorry about that! I made a separate rebase cl upload this time as suggested.

I addressed your inline comments and added "may" to the claim that testing
requires building on the wiki page
(https://code.google.com/p/dart/source/detail?r=39820). This changes are all
really simple, so I'm just going to go ahead with the dcommit. Let me know if
it's instead preferable to wait on *all* changes before dcommiting.

>
https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
> File tests/language/issue18628_1_test.dart (right):
> 
>
https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
> tests/language/issue18628_1_test.dart:15: C<Type> c = new C<Type>();
> You have to use the field 't' to force it to be compiled with tree-shaking.
> 
>
https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
> File tests/language/issue18628_2_test.dart (right):
> 
>
https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
> tests/language/issue18628_2_test.dart:14: class Y<U> extends X<U> {} /// 01:
> static type warning
> Add newlines between class and function declarations.

[Nathan Collins, 2014-09-03 18:50:07]

https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
File tests/language/issue18628_1_test.dart (right):

https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
tests/language/issue18628_1_test.dart:15: C<Type> c = new C<Type>();
On 2014/09/03 06:48:59, karlklose wrote:
> You have to use the field 't' to force it to be compiled with tree-shaking.

Done.

https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
File tests/language/issue18628_2_test.dart (right):

https://codereview.chromium.org/521773003/diff/20001/tests/language/issue1862...
tests/language/issue18628_2_test.dart:14: class Y<U> extends X<U> {} /// 01:
static type warning
On 2014/09/03 06:48:59, karlklose wrote:
> Add newlines between class and function declarations.

Done.

[Nathan Collins, 2014-09-03 18:51:32]

Committed patchset #4 manually as 39822 (presubmit successful).

[karlklose, 2014-09-04 07:52:55]

On 2014/09/03 18:49:49, Nathan Collins wrote:
> On 2014/09/03 06:48:59, karlklose wrote:
> > LGTM.
> > 
> > To make reviewing patchsets easier, please either do not rebase between
> uploads
> > or upload a rebase patchset before uploading the changes that are done on
the
> > rebased code.
> > 
> > In this CL, the delta of patchset 2 to patchset 1 seems to include changes
to
> > the test infrastructure, but the whole patch does not, which can be
confusing
> > during code review.
> 
> Sorry about that! I made a separate rebase cl upload this time as suggested.
> 
> I addressed your inline comments and added "may" to the claim that testing
> requires building on the wiki page
> (https://code.google.com/p/dart/source/detail?r=39820). This changes are all
> really simple, so I'm just going to go ahead with the dcommit. Let me know if
> it's instead preferable to wait on *all* changes before dcommiting.

No problem. From me, an LGTM with comments means that you are free to commit
once you are sure that you have addressed the comments.