Add support for evaluating platform selectors.

Add support for evaluating platform selectors.

See #6

R=rnystrom@google.com

Committed: https://github.com/dart-lang/unittest/commit/033d7b0f62bb396a3019f13c21636c03cb57339f

[Bob Nystrom, 2015-03-16 16:54:26]

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/operating_s...
File lib/src/backend/operating_system.dart (right):

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/operating_s...
lib/src/backend/operating_system.dart:17: static const macOs = const
OperatingSystem._("mac-os", isPosix: true);
"macOS".

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/operating_s...
lib/src/backend/operating_system.dart:17: static const macOs = const
OperatingSystem._("mac-os", isPosix: true);
"macOS".

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/operating_s...
lib/src/backend/operating_system.dart:61: final bool isPosix;
How about just:

bool get isPosix => this != OperatingSystem.windows;

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
File lib/src/backend/platform_selector.dart (right):

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
lib/src/backend/platform_selector.dart:22: /// An expressing for selecting
certain platforms, including operating systems
"expressing" -> "expression".

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
lib/src/backend/platform_selector.dart:40: /// Evaluates the selector against
the given [platform] and [os].
How about something that explains what the evaluation does. Maybe like "Returns
`true` if the selector matches [platform] and [os]."

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
File lib/src/backend/platform_selector/evaluator.dart (right):

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
lib/src/backend/platform_selector/evaluator.dart:30: }
Are these false cases needed?

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
lib/src/backend/platform_selector/evaluator.dart:45: 'Undefined variable
"${node.name}".', node.span);
If you've already done the check for undefined variables, how about just
returning false here and eliminating the explicit false checks above?

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/test_platfo...
File lib/src/backend/test_platform.dart (right):

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/test_platfo...
lib/src/backend/test_platform.dart:18: isBrowser: true, isDart2js: true,
isBlink: true);
Firefox, Safari, IE, et. al.?

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/test_platfo...
lib/src/backend/test_platform.dart:43: final bool isDart2js;
What about DDC? Should this name be more generic?

[nweiz, 2015-03-24 01:03:14]

Code review changes

[nweiz, 2015-03-24 01:03:28]

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/operating_s...
File lib/src/backend/operating_system.dart (right):

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/operating_s...
lib/src/backend/operating_system.dart:17: static const macOs = const
OperatingSystem._("mac-os", isPosix: true);
On 2015/03/16 16:54:26, Bob Nystrom wrote:
> "macOS".

Done.

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/operating_s...
lib/src/backend/operating_system.dart:61: final bool isPosix;
On 2015/03/16 16:54:26, Bob Nystrom wrote:
> How about just:
> 
> bool get isPosix => this != OperatingSystem.windows;

Done.

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
File lib/src/backend/platform_selector.dart (right):

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
lib/src/backend/platform_selector.dart:22: /// An expressing for selecting
certain platforms, including operating systems
On 2015/03/16 16:54:26, Bob Nystrom wrote:
> "expressing" -> "expression".

Done.

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
lib/src/backend/platform_selector.dart:40: /// Evaluates the selector against
the given [platform] and [os].
On 2015/03/16 16:54:26, Bob Nystrom wrote:
> How about something that explains what the evaluation does. Maybe like
"Returns
> `true` if the selector matches [platform] and [os]."

Done.

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
File lib/src/backend/platform_selector/evaluator.dart (right):

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
lib/src/backend/platform_selector/evaluator.dart:30: }
On 2015/03/16 16:54:26, Bob Nystrom wrote:
> Are these false cases needed?

Done.

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/platform_se...
lib/src/backend/platform_selector/evaluator.dart:45: 'Undefined variable
"${node.name}".', node.span);
On 2015/03/16 16:54:26, Bob Nystrom wrote:
> If you've already done the check for undefined variables, how about just
> returning false here and eliminating the explicit false checks above?

Done.

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/test_platfo...
File lib/src/backend/test_platform.dart (right):

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/test_platfo...
lib/src/backend/test_platform.dart:18: isBrowser: true, isDart2js: true,
isBlink: true);
On 2015/03/16 16:54:26, Bob Nystrom wrote:
> Firefox, Safari, IE, et. al.?

This enum is also used for telling other APIs which platforms to run tests on,
and those platforms aren't (currently) supported.

https://codereview.chromium.org/1004013002/diff/1/lib/src/backend/test_platfo...
lib/src/backend/test_platform.dart:43: final bool isDart2js;
On 2015/03/16 16:54:26, Bob Nystrom wrote:
> What about DDC? Should this name be more generic?

Changed to "js".

[Bob Nystrom, 2015-03-24 23:45:34]

lgtm

[nweiz, 2015-03-25 00:24:29]

Committed patchset #2 (id:20001) manually as
033d7b0f62bb396a3019f13c21636c03cb57339f (presubmit successful).