GN: Throw an error overwriting a nonempty scope.

GN: Throw an error overwriting a nonempty scope.

Previously GN would throw an error if you assigned a nonempty list to another
nonempty list. This is easy to mess up when you actually meant to append.
However, it did not have this protection for "scope"-type values.

Adds such protection to scope-type values, and add unit tests for both
behaviors.

Does some unit test cleanup for the operators unit tests to make them easier to
write.

BUG=

Committed: https://crrev.com/56350de24ed370f955b299022e93229f8643ace8
Cr-Commit-Position: refs/heads/master@{#410874}

[brettw, 2016-08-09 22:08:33]

The CQ bit was checked by brettw@chromium.org to run a CQ dry run

[brettw, 2016-08-09 22:08:59]

brettw@chromium.org changed reviewers:
+ scottmg@chromium.org

[commit-bot: I haz the power, 2016-08-09 22:09:09]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[scottmg, 2016-08-09 22:20:33]

lgtm

https://codereview.chromium.org/2224343003/diff/20001/tools/gn/operators.cc
File tools/gn/operators.cc (right):

https://codereview.chromium.org/2224343003/diff/20001/tools/gn/operators.cc#n...
tools/gn/operators.cc:332: if (old_value->type() == Value::LIST && right.type()
== Value::LIST &&
Something else will catch it if I try to overwrite a scope with a list or a list
with a scope, right?

[brettw, 2016-08-09 23:00:48]

https://codereview.chromium.org/2224343003/diff/20001/tools/gn/operators.cc
File tools/gn/operators.cc (right):

https://codereview.chromium.org/2224343003/diff/20001/tools/gn/operators.cc#n...
tools/gn/operators.cc:332: if (old_value->type() == Value::LIST && right.type()
== Value::LIST &&
Presumably that will just be wrong. If changing the type is actually OK, I don't
see a need to warn about it.

[brettw, 2016-08-09 23:00:52]

The CQ bit was unchecked by brettw@chromium.org

[brettw, 2016-08-09 23:00:57]

The CQ bit was checked by brettw@chromium.org

[commit-bot: I haz the power, 2016-08-09 23:02:16]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-09 23:44:12]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-08-09 23:45:52]

Description was changed from

==========
GN: Throw an error overwriting a nonempty scope.

Previously GN would throw an error if you assigned a nonempty list to another
nonempty list. This is easy to mess up when you actually meant to append.
However, it did not have this protection for "scope"-type values.

Adds such protection to scope-type values, and add unit tests for both
behaviors.

Does some unit test cleanup for the operators unit tests to make them easier to
write.

BUG=
==========

to

==========
GN: Throw an error overwriting a nonempty scope.

Previously GN would throw an error if you assigned a nonempty list to another
nonempty list. This is easy to mess up when you actually meant to append.
However, it did not have this protection for "scope"-type values.

Adds such protection to scope-type values, and add unit tests for both
behaviors.

Does some unit test cleanup for the operators unit tests to make them easier to
write.

BUG=

Committed: https://crrev.com/56350de24ed370f955b299022e93229f8643ace8
Cr-Commit-Position: refs/heads/master@{#410874}
==========

[commit-bot: I haz the power, 2016-08-09 23:45:54]

Patchset 2 (id:??) landed as
https://crrev.com/56350de24ed370f955b299022e93229f8643ace8
Cr-Commit-Position: refs/heads/master@{#410874}