Fix for error states on logout/login

This fixes an issue where logging in, then logging out and opening
the login form will reveal a form with error messages. This is due
to the execution order of events post login.

https://github.com/hypothesis/h/pull/1275#issuecomment-51777983

h/static/scripts/directives.coffee

@@ -48,6 +48,11 @@ formValidate = ['$timeout', ($timeout) ->
         isSubmitted = false
     , true
 
+    scope.$watch form.$name + '.$pristine', (value) ->
+      if value == true
+        forEachField (field) ->
+          toggleClass(field, addClass: false)
+
   require: 'form'
 ]
 

tests/js/directives-test.coffee

@@ -121,6 +121,21 @@ describe 'h.directives', ->
 
       assert.notInclude($field.prop('className'), 'form-field-error')
 
+    # No idea why this is failing, it works for the login form...
+    it 'should hide errors if the field is pristine', ->
+      $field = $element.find('.form-field').addClass('form-field-error')
+      $input = $element.find('[name=username]')
+
+      formController = $input.controller('form')
+      modelController = $input.controller('ngModel')
+      modelController.$setViewValue('a') # Change the model state to $dirty
+
+      # Clear out the model and set to $pristine
+      $scope.model = {}
+      formController.$setPristine()
+
+      assert.notInclude($field.prop('className'), 'form-field-error')
+
   describe '.username', ->
     $element = null