If two Maps are compared with an equals() matcher and they have the same length,

If two Maps are compared with an equals() matcher and they have the same length,
show the first key missing from 'actual' that is in 'expected'.

See https://code.google.com/p/dart/issues/detail?id=6814
Committed: https://code.google.com/p/dart/source/detail?r=18347

[gram, 2013-02-09 01:32:51]

AH, ignore this. I realise that it already shows the map key, so now it is
showing twice!

[gram, 2013-02-09 01:36:39]

I kept the new test at least, so please check that. That seems to be what you
asked for in which case I wonder if you just didn't notice that the key was
there when you created the bug?

[Jennifer Messerly, 2013-02-09 23:53:06]

https://codereview.chromium.org/12210100/diff/1/pkg/unittest/lib/src/core_mat...
File pkg/unittest/lib/src/core_matchers.dart (right):

https://codereview.chromium.org/12210100/diff/1/pkg/unittest/lib/src/core_mat...
pkg/unittest/lib/src/core_matchers.dart:144: reason = new
StringDescription('different map lengths');
The bug was about this line. Unless I'm really confused :), if map length is
different, we only print "different map lengths". The "missing map key" message
only prints if the lengths are the same.

[Jennifer Messerly, 2013-02-10 00:01:40]

https://codereview.chromium.org/12210100/diff/1/pkg/unittest/lib/src/core_mat...
File pkg/unittest/lib/src/core_matchers.dart (right):

https://codereview.chromium.org/12210100/diff/1/pkg/unittest/lib/src/core_mat...
pkg/unittest/lib/src/core_matchers.dart:144: reason = new
StringDescription('different map lengths');
Here's a possible way to refactor this code. Not sure if I'm using the
StringDescription class correctly but this is the the general idea. Basically
the problem I'm trying to solve is that "different map length" isn't a useful
message on its own, it helps to know why it's different -- was their an extra
key, or too few keys? Basically I need to see the full "diff" :)  to quickly
diagnose why the test failed.



if (actual is !Map) {
 ...
} else {
  var reason = new StringDescription();
  if (expected.length != actual.length) {
    reason.add('different map length, ');
  }
  for (var key in expected.keys) {
    if (!actual.containsKey(key)) {
      reason.add('missing map key');
      reason.addDescriptionOf(key);
      break;
    }
    var valueReason = _recursiveMatch(expected[key], actual[key], ...));
    if (valueReason != null) {
      reason.add(valueReason);
      break;
    }
  }
  // NOTE: down here it also needs to handle the case where "actual" has a key
but "expected" does not.
}

[gram, 2013-02-11 20:43:35]

PTAL

https://codereview.chromium.org/12210100/diff/1/pkg/unittest/lib/src/core_mat...
File pkg/unittest/lib/src/core_matchers.dart (right):

https://codereview.chromium.org/12210100/diff/1/pkg/unittest/lib/src/core_mat...
pkg/unittest/lib/src/core_matchers.dart:144: reason = new
StringDescription('different map lengths');
On 2013/02/09 23:53:06, John Messerly wrote:
> The bug was about this line. Unless I'm really confused :), if map length is
> different, we only print "different map lengths". The "missing map key"
message
> only prints if the lengths are the same.

 I have changed it so that it will print the mismatched length message plus one
key message (missing/extra)

[Jennifer Messerly, 2013-02-11 20:59:01]

lgtm!