Include record in ActiveRecord::RecordNotSaved

Include the relation required to be saved in the
`ActiveRecord::RecordNotSaved` exception raised when saving an association
that requires the record to be saved.

Example:

```ruby
class Post < ApplicationRecord
  has_many :comments

  validates :title, presence: true
end

class Comment < ApplicationRecord
  belongs_to :post
end
```

* Before the fix

``` ruby
>> post = Post.new(title: :foo)
=> #<Post id: nil, title: "foo", body: nil, created_at: nil, updated_at: nil>
>> post.comments.create!
Traceback (most recent call last):
        1: from (irb):2
ActiveRecord::RecordNotSaved (You cannot call create unless the parent is saved)
>> e = _
=> #<ActiveRecord::RecordNotSaved: You cannot call create unless the parent is saved>
>> e.record
=> nil
```

* After the fix

```ruby
>> post = Post.new(title: :foo)
=> #<Post id: nil, title: "foo", body: nil, created_at: nil, updated_at: nil>
>> post.comments.create!
Traceback (most recent call last):
        1: from (irb):2
ActiveRecord::RecordNotSaved (You cannot call create unless the parent is saved)
>> e = _
=> #<ActiveRecord::RecordNotSaved: You cannot call create unless the parent is saved>
>> e.record
=> #<Post id: nil, title: "foo", body: nil, created_at: nil, updated_at: nil>
```

Author: kassio

activerecord/lib/active_record/associations/collection_association.rb

@@ -338,7 +338,7 @@ def merge_target_lists(persisted, memory)
 
         def _create_record(attributes, raise = false, &block)
           unless owner.persisted?
-            raise ActiveRecord::RecordNotSaved, "You cannot call create unless the parent is saved"
+            raise ActiveRecord::RecordNotSaved.new("You cannot call create unless the parent is saved", owner)
           end
 
           if attributes.is_a?(Array)

activerecord/lib/active_record/associations/has_one_association.rb

@@ -70,7 +70,7 @@ def replace(record, save = true)
                 if save && !record.save
                   nullify_owner_attributes(record)
                   set_owner_attributes(target) if target
-                  raise RecordNotSaved, "Failed to save the new associated #{reflection.name}."
+                  raise RecordNotSaved.new("Failed to save the new associated #{reflection.name}.", record)
                 end
               end
             end
@@ -102,8 +102,11 @@ def remove_target!(method)
 
             if target.persisted? && owner.persisted? && !target.save
               set_owner_attributes(target)
-              raise RecordNotSaved, "Failed to remove the existing associated #{reflection.name}. " \
-                                    "The record failed to save after its foreign key was set to nil."
+              raise RecordNotSaved.new(
+                "Failed to remove the existing associated #{reflection.name}. " \
+                "The record failed to save after its foreign key was set to nil.",
+                target
+              )
             end
           end
         end
@@ -122,7 +125,7 @@ def transaction_if(value)
 
         def _create_record(attributes, raise_error = false, &block)
           unless owner.persisted?
-            raise ActiveRecord::RecordNotSaved, "You cannot call create unless the parent is saved"
+            raise ActiveRecord::RecordNotSaved.new("You cannot call create unless the parent is saved", owner)
           end
 
           super

activerecord/test/cases/associations/has_many_associations_test.rb

@@ -1034,21 +1034,23 @@ def test_adding_using_create
   end
 
   def test_create_with_bang_on_has_many_when_parent_is_new_raises
+    firm = Firm.new
     error = assert_raise(ActiveRecord::RecordNotSaved) do
-      firm = Firm.new
       firm.plain_clients.create! name: "Whoever"
     end
 
     assert_equal "You cannot call create unless the parent is saved", error.message
+    assert_equal firm, error.record
   end
 
   def test_regular_create_on_has_many_when_parent_is_new_raises
+    firm = Firm.new
     error = assert_raise(ActiveRecord::RecordNotSaved) do
-      firm = Firm.new
       firm.plain_clients.create name: "Whoever"
     end
 
     assert_equal "You cannot call create unless the parent is saved", error.message
+    assert_equal firm, error.record
   end
 
   def test_create_with_bang_on_has_many_raises_when_record_not_saved
@@ -1059,11 +1061,13 @@ def test_create_with_bang_on_has_many_raises_when_record_not_saved
   end
 
   def test_create_with_bang_on_habtm_when_parent_is_new_raises
+    developer = Developer.new("name" => "Aredridel")
     error = assert_raise(ActiveRecord::RecordNotSaved) do
-      Developer.new("name" => "Aredridel").projects.create!
+      developer.projects.create!
     end
 
     assert_equal "You cannot call create unless the parent is saved", error.message
+    assert_equal developer, error.record
   end
 
   def test_adding_a_mismatch_class

activerecord/test/cases/associations/has_one_associations_test.rb

@@ -340,6 +340,7 @@ def test_create_when_parent_is_new_raises
     end
 
     assert_equal "You cannot call create unless the parent is saved", error.message
+    assert_equal firm, error.record
   end
 
   def test_reload_association
@@ -519,6 +520,7 @@ def test_creation_failure_due_to_new_record_should_raise_error
     end
 
     assert_equal "Failed to save the new associated ship.", error.message
+    assert_equal new_ship, error.record
     assert_nil pirate.ship
     assert_nil new_ship.pirate_id
   end
@@ -536,6 +538,7 @@ def test_replacement_failure_due_to_existing_record_should_raise_error
     assert_equal pirate.id, pirate.ship.pirate_id
     assert_equal "Failed to remove the existing associated ship. " \
                  "The record failed to save after its foreign key was set to nil.", error.message
+    assert_equal pirate.ship, error.record
   end
 
   def test_replacement_failure_due_to_new_record_should_raise_error
@@ -547,6 +550,7 @@ def test_replacement_failure_due_to_new_record_should_raise_error
     end
 
     assert_equal "Failed to save the new associated ship.", error.message
+    assert_equal new_ship, error.record
     assert_equal ships(:black_pearl), pirate.ship
     assert_equal pirate.id, pirate.ship.pirate_id
     assert_equal pirate.id, ships(:black_pearl).reload.pirate_id