Fix validation checks so that all associated records are validated (mongodb#5881)

It was previously stopping at the first failed validation.

Author: jamis

lib/mongoid/validatable/associated.rb

@@ -69,13 +69,16 @@ def validate_association(document, attribute)
           # Now, treating the target as an array, look at each element
           # and see if it is valid, but only if it has already been
           # persisted, or changed, and hasn't been flagged for destroy.
-          list.all? do |value|
+          #
+          # use map.all? instead of just all?, because all? will do short-circuit
+          # evaluation and terminate on the first failed validation.
+          list.map do |value|
             if value && !value.flagged_for_destroy? && (!value.persisted? || value.changed?)
               value.validated? ? true : value.valid?
             else
               true
             end
-          end
+          end.all?
         end
 
         document.errors.add(attribute, :invalid) unless valid

spec/mongoid/validatable/associated_spec.rb

@@ -37,25 +37,35 @@
           User.new(name: "test")
         end
 
-        let(:description) do
+        let(:description1) do
+          Description.new
+        end
+
+        let(:description2) do
           Description.new
         end
 
         before do
-          user.descriptions << description
+          user.descriptions << description1
+          user.descriptions << description2
+          user.valid?
         end
 
         it "only validates the parent once" do
           expect(user).to_not be_valid
         end
 
         it "adds the errors from the relation" do
-          user.valid?
           expect(user.errors[:descriptions]).to_not be_nil
         end
 
+        it 'reports all failed validations' do
+          errors = user.descriptions.flat_map { |d| d.errors[:details] }
+          expect(errors.length).to be == 2
+        end
+
         it "only validates the child once" do
-          expect(description).to_not be_valid
+          expect(description1).to_not be_valid
         end
       end