From aff8705cf6baf3ab55ec8d25d6c19b9c436ac7a0 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Sun, 4 Jul 2021 09:09:16 -0400
Subject: [PATCH 01/15] replace settings

---
 lib/dry/configurable/settings.rb              |  7 ++++
 .../dry/configurable/setting_spec.rb          | 38 +++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/lib/dry/configurable/settings.rb b/lib/dry/configurable/settings.rb
index 3784e17d..a92f799b 100644
--- a/lib/dry/configurable/settings.rb
+++ b/lib/dry/configurable/settings.rb
@@ -23,6 +23,13 @@ def initialize(elements = EMPTY_ARRAY)
         initialize_elements(elements)
       end
 
+      def replace(settings)
+        raise ArgumentError, "settings must be a Dry::Configurable::Settings" unless settings.is_a? Dry::Configurable::Settings
+        settings.each do |setting|
+          self << setting
+        end
+      end
+
       # @api private
       def <<(setting)
         elements[setting.name] = setting
diff --git a/spec/integration/dry/configurable/setting_spec.rb b/spec/integration/dry/configurable/setting_spec.rb
index cb981120..5d7a3ebc 100644
--- a/spec/integration/dry/configurable/setting_spec.rb
+++ b/spec/integration/dry/configurable/setting_spec.rb
@@ -185,6 +185,44 @@
 
     include_context "configurable behavior"
 
+    context "can be configured with another class's settings" do 
+      let(:other_klass) do 
+        Class.new do 
+          extend Dry::Configurable
+        end
+      end
+
+      it "replaces with each" do 
+        klass.setting :hello, "world"
+        klass._settings.each do |setting|
+          other_klass._settings << setting.dup
+        end
+        expect(other_klass.config.hello).to eql("world")
+      end
+
+      it "replaces with replace" do 
+        klass.setting :hello, "world" 
+        other_klass._settings.replace(klass._settings.dup)
+        expect(other_klass.config.hello).to eql("world")
+      end
+
+      it "deep replace" do 
+        klass.setting :database do
+          setting :dsn, "localhost"
+        end
+
+        other_klass._settings.replace(klass._settings.dup)
+        expect(other_klass.config.database.dsn).to eql('localhost')
+      end
+
+      it "throws an error if the settings aren't Dry::Configurable::Settings" do 
+        klass.setting :hello, "world"
+        expect{ other_klass._settings.replace(klass) }.to raise_error do |error|
+          expect(error.class).to be(ArgumentError)
+        end
+      end
+    end
+
     context "with a subclass" do
       let(:subclass) do
         Class.new(klass)

From 5352a895e6f35a7da677fed79aa0c97f6fb37a76 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Sun, 4 Jul 2021 09:52:41 -0400
Subject: [PATCH 02/15] fix formatting

---
 lib/dry/configurable/settings.rb | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/dry/configurable/settings.rb b/lib/dry/configurable/settings.rb
index a92f799b..c4910ffe 100644
--- a/lib/dry/configurable/settings.rb
+++ b/lib/dry/configurable/settings.rb
@@ -24,7 +24,10 @@ def initialize(elements = EMPTY_ARRAY)
       end
 
       def replace(settings)
-        raise ArgumentError, "settings must be a Dry::Configurable::Settings" unless settings.is_a? Dry::Configurable::Settings
+        unless settings.is_a? Dry::Configurable::Settings
+          raise ArgumentError, "settings must be a Dry::Configurable::Settings"
+        end
+        
         settings.each do |setting|
           self << setting
         end

From 25d76211f4d9c186ca95f517f061fba931beb9f7 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Sun, 4 Jul 2021 09:58:32 -0400
Subject: [PATCH 03/15] remove whitespace

---
 lib/dry/configurable/settings.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/dry/configurable/settings.rb b/lib/dry/configurable/settings.rb
index c4910ffe..84c57e21 100644
--- a/lib/dry/configurable/settings.rb
+++ b/lib/dry/configurable/settings.rb
@@ -27,7 +27,7 @@ def replace(settings)
         unless settings.is_a? Dry::Configurable::Settings
           raise ArgumentError, "settings must be a Dry::Configurable::Settings"
         end
-        
+
         settings.each do |setting|
           self << setting
         end

From b4c6371a3991889ca40bb1fd28869862c192b787 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Tue, 20 Jul 2021 07:00:35 -0400
Subject: [PATCH 04/15] rubocop fixes

---
 Gemfile                                       | 10 +++++-----
 Rakefile                                      |  4 ++--
 bin/console                                   |  8 ++++----
 .../dry/configurable/setting_spec.rb          | 20 +++++++++----------
 4 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/Gemfile b/Gemfile
index 0ccff33a..2ef950b4 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,16 +1,16 @@
 # frozen_string_literal: true
 
-source 'https://rubygems.org'
+source "https://rubygems.org"
 
-eval_gemfile 'Gemfile.devtools'
+eval_gemfile "Gemfile.devtools"
 
 gemspec
 
 group :benchmarks do
-  gem 'benchmark-ips'
+  gem "benchmark-ips"
 end
 
 group :tools do
-  gem 'hotch'
-  gem 'pry-byebug', platform: :mri
+  gem "hotch"
+  gem "pry-byebug", platform: :mri
 end
diff --git a/Rakefile b/Rakefile
index ad52f833..be26d08b 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,8 +1,8 @@
 # frozen_string_literal: true
 
-require 'rspec/core/rake_task'
+require "rspec/core/rake_task"
 
-desc 'Run all specs in spec directory'
+desc "Run all specs in spec directory"
 RSpec::Core::RakeTask.new(:spec)
 
 task default: :spec
diff --git a/bin/console b/bin/console
index 936f50ef..0afe5714 100755
--- a/bin/console
+++ b/bin/console
@@ -1,13 +1,13 @@
 #!/usr/bin/env ruby
 # frozen_string_literal: true
 
-require 'bundler/setup'
-require 'dry/configurable'
+require "bundler/setup"
+require "dry/configurable"
 
 begin
-  require 'pry-byebug'
+  require "pry-byebug"
   Pry.start
 rescue LoadError
-  require 'irb'
+  require "irb"
   IRB.start
 end
diff --git a/spec/integration/dry/configurable/setting_spec.rb b/spec/integration/dry/configurable/setting_spec.rb
index 5d7a3ebc..8a72775b 100644
--- a/spec/integration/dry/configurable/setting_spec.rb
+++ b/spec/integration/dry/configurable/setting_spec.rb
@@ -185,14 +185,14 @@
 
     include_context "configurable behavior"
 
-    context "can be configured with another class's settings" do 
-      let(:other_klass) do 
-        Class.new do 
+    context "can be configured with another class's settings" do
+      let(:other_klass) do
+        Class.new do
           extend Dry::Configurable
         end
       end
 
-      it "replaces with each" do 
+      it "replaces with each" do
         klass.setting :hello, "world"
         klass._settings.each do |setting|
           other_klass._settings << setting.dup
@@ -200,24 +200,24 @@
         expect(other_klass.config.hello).to eql("world")
       end
 
-      it "replaces with replace" do 
-        klass.setting :hello, "world" 
+      it "replaces with replace" do
+        klass.setting :hello, "world"
         other_klass._settings.replace(klass._settings.dup)
         expect(other_klass.config.hello).to eql("world")
       end
 
-      it "deep replace" do 
+      it "deep replace" do
         klass.setting :database do
           setting :dsn, "localhost"
         end
 
         other_klass._settings.replace(klass._settings.dup)
-        expect(other_klass.config.database.dsn).to eql('localhost')
+        expect(other_klass.config.database.dsn).to eql("localhost")
       end
 
-      it "throws an error if the settings aren't Dry::Configurable::Settings" do 
+      it "throws an error if the settings aren't Dry::Configurable::Settings" do
         klass.setting :hello, "world"
-        expect{ other_klass._settings.replace(klass) }.to raise_error do |error|
+        expect { other_klass._settings.replace(klass) }.to raise_error do |error|
           expect(error.class).to be(ArgumentError)
         end
       end

From f2cc0334bc41358f0db4c5bceedc01cecb28e1a9 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Tue, 20 Jul 2021 08:38:11 -0400
Subject: [PATCH 05/15] attempt at merge

---
 lib/dry/configurable/setting.rb               |  5 ++++
 lib/dry/configurable/settings.rb              | 14 +++++++++++
 .../dry/configurable/setting_spec.rb          | 24 +++++++++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/lib/dry/configurable/setting.rb b/lib/dry/configurable/setting.rb
index dd36f023..c4e23dbf 100644
--- a/lib/dry/configurable/setting.rb
+++ b/lib/dry/configurable/setting.rb
@@ -69,6 +69,11 @@ def initialize(name, input: Undefined, default: Undefined, **options)
         evaluate if input_defined?
       end
 
+      def merge(setting)
+        input.merge(setting.input) if input_defined?
+        evaluate
+      end
+
       # @api private
       def input_defined?
         !input.equal?(Undefined)
diff --git a/lib/dry/configurable/settings.rb b/lib/dry/configurable/settings.rb
index 84c57e21..d316dd12 100644
--- a/lib/dry/configurable/settings.rb
+++ b/lib/dry/configurable/settings.rb
@@ -33,6 +33,20 @@ def replace(settings)
         end
       end
 
+      def merge(settings)
+        settings.each do |setting|
+          merge_setting(setting)
+        end
+      end
+
+      def merge_setting(setting)
+        if key?(setting.name)
+          elements[setting.name].merge(setting)
+        else
+          self << setting
+        end
+      end
+
       # @api private
       def <<(setting)
         elements[setting.name] = setting
diff --git a/spec/integration/dry/configurable/setting_spec.rb b/spec/integration/dry/configurable/setting_spec.rb
index 8a72775b..f2cce0f2 100644
--- a/spec/integration/dry/configurable/setting_spec.rb
+++ b/spec/integration/dry/configurable/setting_spec.rb
@@ -192,6 +192,30 @@
         end
       end
 
+      it "should deep merge" do
+        klass.setting :database do
+          setting :type, "postgresql"
+          setting :host, "remote"
+          setting :port, 12_345
+          setting :deep do
+            setting :one, 1
+            setting :two, 2
+          end
+        end
+
+        other_klass.setting :database do
+          setting :host, "localhost"
+          setting :port
+          setting :deep, 3
+        end
+
+        other_klass._settings.merge(klass._settings.dup)
+        expect(other_klass.config.database.host).to eql("localhost")
+        expect(other_klass.config.database.port).to eql(nil)
+        expect(other_klass.config.database.type).to eql("postgresql")
+        expect(other_klass.config.database.deep).to eql(3)
+      end
+
       it "replaces with each" do
         klass.setting :hello, "world"
         klass._settings.each do |setting|

From c8853d89744d7acd808e15827244b194ce9fd49f Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Tue, 20 Jul 2021 19:30:35 -0400
Subject: [PATCH 06/15] merge settings

---
 lib/dry/configurable/settings.rb | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/dry/configurable/settings.rb b/lib/dry/configurable/settings.rb
index d316dd12..b476cc1d 100644
--- a/lib/dry/configurable/settings.rb
+++ b/lib/dry/configurable/settings.rb
@@ -34,11 +34,15 @@ def replace(settings)
       end
 
       def merge(settings)
+        unless settings.is_a? Dry::Configurable::Settings
+          raise ArgumentError, "settings must be a Dry::Configurable::Settings"
+        end
         settings.each do |setting|
           merge_setting(setting)
         end
       end
 
+      # @api private
       def merge_setting(setting)
         if key?(setting.name)
           elements[setting.name].merge(setting)

From acf53fdec3ad077c567810ccb0cd698d173a1a4f Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Tue, 20 Jul 2021 19:34:58 -0400
Subject: [PATCH 07/15] empty line after guard clause

---
 lib/dry/configurable/settings.rb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/dry/configurable/settings.rb b/lib/dry/configurable/settings.rb
index b476cc1d..4b489b59 100644
--- a/lib/dry/configurable/settings.rb
+++ b/lib/dry/configurable/settings.rb
@@ -37,6 +37,7 @@ def merge(settings)
         unless settings.is_a? Dry::Configurable::Settings
           raise ArgumentError, "settings must be a Dry::Configurable::Settings"
         end
+        
         settings.each do |setting|
           merge_setting(setting)
         end

From 2e435c1acf0fae9d352eee5f28a22f4b25a1ce06 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Tue, 20 Jul 2021 19:40:14 -0400
Subject: [PATCH 08/15] trailing whitespace

---
 lib/dry/configurable/settings.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/dry/configurable/settings.rb b/lib/dry/configurable/settings.rb
index 4b489b59..5c1c93a4 100644
--- a/lib/dry/configurable/settings.rb
+++ b/lib/dry/configurable/settings.rb
@@ -37,7 +37,7 @@ def merge(settings)
         unless settings.is_a? Dry::Configurable::Settings
           raise ArgumentError, "settings must be a Dry::Configurable::Settings"
         end
-        
+
         settings.each do |setting|
           merge_setting(setting)
         end

From 58adf9bc8c57fea3d8179dae85b09f1f5215a85b Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Thu, 22 Jul 2021 19:35:35 -0400
Subject: [PATCH 09/15] remove replace, add Settings#merge, and Settings#merge!

---
 lib/dry/configurable/setting.rb               | 10 +--
 lib/dry/configurable/settings.rb              | 39 ++++----
 .../dry/configurable/setting_spec.rb          | 62 -------------
 .../dry/configurable/settings_spec.rb         | 89 +++++++++++++++++++
 4 files changed, 113 insertions(+), 87 deletions(-)
 create mode 100644 spec/integration/dry/configurable/settings_spec.rb

diff --git a/lib/dry/configurable/setting.rb b/lib/dry/configurable/setting.rb
index c4e23dbf..dfe19552 100644
--- a/lib/dry/configurable/setting.rb
+++ b/lib/dry/configurable/setting.rb
@@ -42,6 +42,11 @@ class Setting
       class Nested < Setting
         CONSTRUCTOR = Config.method(:new)
 
+        def merge(setting)
+          settings = input.merge(setting.input)
+          Nested.new(name, input: settings, **options)
+        end
+
         # @api private
         def pristine
           with(input: input.pristine)
@@ -69,11 +74,6 @@ def initialize(name, input: Undefined, default: Undefined, **options)
         evaluate if input_defined?
       end
 
-      def merge(setting)
-        input.merge(setting.input) if input_defined?
-        evaluate
-      end
-
       # @api private
       def input_defined?
         !input.equal?(Undefined)
diff --git a/lib/dry/configurable/settings.rb b/lib/dry/configurable/settings.rb
index 5c1c93a4..d8a2dc41 100644
--- a/lib/dry/configurable/settings.rb
+++ b/lib/dry/configurable/settings.rb
@@ -23,32 +23,17 @@ def initialize(elements = EMPTY_ARRAY)
         initialize_elements(elements)
       end
 
-      def replace(settings)
-        unless settings.is_a? Dry::Configurable::Settings
-          raise ArgumentError, "settings must be a Dry::Configurable::Settings"
-        end
-
-        settings.each do |setting|
+      def merge!(settings)
+        merge(settings).each do |setting|
           self << setting
         end
       end
 
       def merge(settings)
-        unless settings.is_a? Dry::Configurable::Settings
-          raise ArgumentError, "settings must be a Dry::Configurable::Settings"
-        end
+        ensure_arguments(settings)
 
-        settings.each do |setting|
-          merge_setting(setting)
-        end
-      end
-
-      # @api private
-      def merge_setting(setting)
-        if key?(setting.name)
-          elements[setting.name].merge(setting)
-        else
-          self << setting
+        settings.dup.inject(dup) do |memo, setting|
+          memo << merge_setting(setting)
         end
       end
 
@@ -85,6 +70,20 @@ def pristine
 
       private
 
+      def merge_setting(setting)
+        if elements[setting.name].is_a? Setting::Nested
+          elements[setting.name].merge(setting)
+        else
+          setting
+        end
+      end
+
+      def ensure_arguments(settings)
+        unless settings.is_a? Dry::Configurable::Settings
+          raise ArgumentError, "settings must be a Dry::Configurable::Settings"
+        end
+      end
+
       # @api private
       def initialize_copy(source)
         initialize_elements(source.map(&:dup))
diff --git a/spec/integration/dry/configurable/setting_spec.rb b/spec/integration/dry/configurable/setting_spec.rb
index f2cce0f2..cb981120 100644
--- a/spec/integration/dry/configurable/setting_spec.rb
+++ b/spec/integration/dry/configurable/setting_spec.rb
@@ -185,68 +185,6 @@
 
     include_context "configurable behavior"
 
-    context "can be configured with another class's settings" do
-      let(:other_klass) do
-        Class.new do
-          extend Dry::Configurable
-        end
-      end
-
-      it "should deep merge" do
-        klass.setting :database do
-          setting :type, "postgresql"
-          setting :host, "remote"
-          setting :port, 12_345
-          setting :deep do
-            setting :one, 1
-            setting :two, 2
-          end
-        end
-
-        other_klass.setting :database do
-          setting :host, "localhost"
-          setting :port
-          setting :deep, 3
-        end
-
-        other_klass._settings.merge(klass._settings.dup)
-        expect(other_klass.config.database.host).to eql("localhost")
-        expect(other_klass.config.database.port).to eql(nil)
-        expect(other_klass.config.database.type).to eql("postgresql")
-        expect(other_klass.config.database.deep).to eql(3)
-      end
-
-      it "replaces with each" do
-        klass.setting :hello, "world"
-        klass._settings.each do |setting|
-          other_klass._settings << setting.dup
-        end
-        expect(other_klass.config.hello).to eql("world")
-      end
-
-      it "replaces with replace" do
-        klass.setting :hello, "world"
-        other_klass._settings.replace(klass._settings.dup)
-        expect(other_klass.config.hello).to eql("world")
-      end
-
-      it "deep replace" do
-        klass.setting :database do
-          setting :dsn, "localhost"
-        end
-
-        other_klass._settings.replace(klass._settings.dup)
-        expect(other_klass.config.database.dsn).to eql("localhost")
-      end
-
-      it "throws an error if the settings aren't Dry::Configurable::Settings" do
-        klass.setting :hello, "world"
-        expect { other_klass._settings.replace(klass) }.to raise_error do |error|
-          expect(error.class).to be(ArgumentError)
-        end
-      end
-    end
-
     context "with a subclass" do
       let(:subclass) do
         Class.new(klass)
diff --git a/spec/integration/dry/configurable/settings_spec.rb b/spec/integration/dry/configurable/settings_spec.rb
new file mode 100644
index 00000000..2dd6471c
--- /dev/null
+++ b/spec/integration/dry/configurable/settings_spec.rb
@@ -0,0 +1,89 @@
+# frozen_string_literal: true
+
+require "pathname"
+
+RSpec.describe Dry::Configurable::Settings do
+  context "can be configured with another class's settings" do
+    let(:klass) do
+      Class.new do
+        extend Dry::Configurable
+      end
+    end
+
+    context "with merge" do
+      let(:other_klass) do
+        Class.new do
+          extend Dry::Configurable
+        end
+      end
+
+      it "should override fields and return a Dry::Configurable::Settings" do
+        klass.setting :database do
+          setting :type, "postgresql"
+          setting :host, "remote"
+        end
+
+        other_klass.setting :database do
+          setting :host, "localhost"
+          setting :port, 54_321
+        end
+
+        settings = other_klass._settings.merge(klass._settings)
+
+        aggregate_failures do
+          expect(settings.class).to be(Dry::Configurable::Settings)
+          expect(settings[:database].input.entries.size).to eql(3)
+          expect(settings[:database].input[:type].default).to eql("postgresql")
+          expect(settings[:database].input[:host].default).to eql("remote")
+          expect(settings[:database].input[:port].default).to eql(54_321)
+        end
+
+        aggregate_failures do
+          expect(other_klass.config.database.host).to eql("localhost")
+          expect(other_klass.config.database.port).to eql(54_321)
+          expect { other_klass.config.database.type }.to raise_error do |error|
+            expect(error.class).to eql(NoMethodError)
+          end
+        end
+
+        aggregate_failures do
+          expect(klass.config.database.host).to eql("remote")
+          expect(klass.config.database.type).to eql("postgresql")
+          expect { klass.config.database.port }.to raise_error do |error|
+            expect(error.class).to eql(NoMethodError)
+          end
+        end
+      end
+    end
+
+    context "with merge!" do
+      let(:other_klass) do
+        Class.new do
+          extend Dry::Configurable
+        end
+      end
+
+      it "replaces undefined fields" do
+        klass.setting :hello, "world"
+        other_klass._settings.merge!(klass._settings)
+        expect(other_klass.config.hello).to eql("world")
+      end
+
+      it "replaces deep fields" do
+        klass.setting :database do
+          setting :dsn, "localhost"
+        end
+
+        other_klass._settings.merge!(klass._settings)
+        expect(other_klass.config.database.dsn).to eql("localhost")
+      end
+
+      it "throws an error if the settings aren't Dry::Configurable::Settings" do
+        klass.setting :hello, "world"
+        expect { other_klass._settings.merge!(klass) }.to raise_error do |error|
+          expect(error.class).to be(ArgumentError)
+        end
+      end
+    end
+  end
+end

From bf1cb1bbb3d341cc343293d1d4ec84edc8badf03 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Thu, 22 Jul 2021 19:51:50 -0400
Subject: [PATCH 10/15] missing spec

---
 spec/integration/dry/configurable/settings_spec.rb | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/spec/integration/dry/configurable/settings_spec.rb b/spec/integration/dry/configurable/settings_spec.rb
index 2dd6471c..550f158f 100644
--- a/spec/integration/dry/configurable/settings_spec.rb
+++ b/spec/integration/dry/configurable/settings_spec.rb
@@ -78,6 +78,17 @@
         expect(other_klass.config.database.dsn).to eql("localhost")
       end
 
+      it "overrides deep fields" do
+        klass.setting :database do
+          setting :dsn, "localhost"
+        end
+        other_klass.setting :database do
+          setting :dsn, "remote"
+        end
+        other_klass._settings.merge!(klass._settings)
+        expect(other_klass.config.database.dsn).to eql("localhost")
+      end
+
       it "throws an error if the settings aren't Dry::Configurable::Settings" do
         klass.setting :hello, "world"
         expect { other_klass._settings.merge!(klass) }.to raise_error do |error|

From fb26421f07251069f17ab6487658fea3331a16a9 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Thu, 22 Jul 2021 21:12:04 -0400
Subject: [PATCH 11/15] use target settings

---
 lib/dry/configurable/setting.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/dry/configurable/setting.rb b/lib/dry/configurable/setting.rb
index dfe19552..e59268c8 100644
--- a/lib/dry/configurable/setting.rb
+++ b/lib/dry/configurable/setting.rb
@@ -44,7 +44,7 @@ class Nested < Setting
 
         def merge(setting)
           settings = input.merge(setting.input)
-          Nested.new(name, input: settings, **options)
+          Nested.new(name, input: settings, **setting.options)
         end
 
         # @api private

From 06932b74927a2f95e7d84042691a3353f91961f8 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Thu, 22 Jul 2021 21:12:32 -0400
Subject: [PATCH 12/15] failing tests when the config has been invoked

---
 .../dry/configurable/settings_spec.rb         | 21 ++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/spec/integration/dry/configurable/settings_spec.rb b/spec/integration/dry/configurable/settings_spec.rb
index 550f158f..2e5d7039 100644
--- a/spec/integration/dry/configurable/settings_spec.rb
+++ b/spec/integration/dry/configurable/settings_spec.rb
@@ -63,6 +63,14 @@
         end
       end
 
+      it "should override a block" do
+        klass.setting(:hello, "bar") { |w| w.chars.join("_") }
+        other_klass.setting(:hello, "fuzz") { |w| w.chars.join("-") }
+        expect(other_klass.config.hello).to eql("f-u-z-z")
+        other_klass._settings.merge!(klass._settings)
+        expect(other_klass.config.hello).to eql("b_a_r")
+      end
+
       it "replaces undefined fields" do
         klass.setting :hello, "world"
         other_klass._settings.merge!(klass._settings)
@@ -73,7 +81,6 @@
         klass.setting :database do
           setting :dsn, "localhost"
         end
-
         other_klass._settings.merge!(klass._settings)
         expect(other_klass.config.database.dsn).to eql("localhost")
       end
@@ -89,6 +96,18 @@
         expect(other_klass.config.database.dsn).to eql("localhost")
       end
 
+      it "should work when the config accessor has already be invoked" do
+        klass.setting :database do
+          setting :dsn, "localhost"
+        end
+        other_klass.setting :database do
+          setting :dsn, "remote"
+        end
+        expect(other_klass.config.database.dsn).to eql("remote")
+        other_klass._settings.merge!(klass._settings)
+        expect(other_klass.config.database.dsn).to eql("localhost")
+      end
+
       it "throws an error if the settings aren't Dry::Configurable::Settings" do
         klass.setting :hello, "world"
         expect { other_klass._settings.merge!(klass) }.to raise_error do |error|

From a153da9e5cd60db8815defbcfc5b2dc1f5d03407 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Thu, 22 Jul 2021 22:12:23 -0400
Subject: [PATCH 13/15] merge non nested settings to nested settings

---
 lib/dry/configurable/settings.rb                   | 2 +-
 spec/integration/dry/configurable/settings_spec.rb | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/lib/dry/configurable/settings.rb b/lib/dry/configurable/settings.rb
index d8a2dc41..cb081fc1 100644
--- a/lib/dry/configurable/settings.rb
+++ b/lib/dry/configurable/settings.rb
@@ -71,7 +71,7 @@ def pristine
       private
 
       def merge_setting(setting)
-        if elements[setting.name].is_a? Setting::Nested
+        if elements[setting.name].is_a?(Setting::Nested) && setting.is_a?(Setting::Nested)
           elements[setting.name].merge(setting)
         else
           setting
diff --git a/spec/integration/dry/configurable/settings_spec.rb b/spec/integration/dry/configurable/settings_spec.rb
index 2e5d7039..6eefefb8 100644
--- a/spec/integration/dry/configurable/settings_spec.rb
+++ b/spec/integration/dry/configurable/settings_spec.rb
@@ -96,6 +96,15 @@
         expect(other_klass.config.database.dsn).to eql("localhost")
       end
 
+      it "shouldn't blow up when merging a non nested setting to a nested setting" do 
+        klass.setting :database, "hello"
+        other_klass.setting :database do
+          setting :dsn, "localhost"
+        end
+        other_klass._settings.merge!(klass._settings)
+        expect(other_klass.config.database).to eql("hello")
+      end
+
       it "should work when the config accessor has already be invoked" do
         klass.setting :database do
           setting :dsn, "localhost"

From 40423c591678018cc3fdd8874e924bcdaf89ef35 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Thu, 22 Jul 2021 22:12:58 -0400
Subject: [PATCH 14/15] fix linting

---
 spec/integration/dry/configurable/settings_spec.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/spec/integration/dry/configurable/settings_spec.rb b/spec/integration/dry/configurable/settings_spec.rb
index 6eefefb8..b95d94a9 100644
--- a/spec/integration/dry/configurable/settings_spec.rb
+++ b/spec/integration/dry/configurable/settings_spec.rb
@@ -96,7 +96,7 @@
         expect(other_klass.config.database.dsn).to eql("localhost")
       end
 
-      it "shouldn't blow up when merging a non nested setting to a nested setting" do 
+      it "shouldn't blow up when merging a non nested setting to a nested setting" do
         klass.setting :database, "hello"
         other_klass.setting :database do
           setting :dsn, "localhost"

From 16238c93133c66c08fdcae965793b6f9f22534d9 Mon Sep 17 00:00:00 2001
From: Sean Gregory <sean.christopher.gregory@gmail.com>
Date: Tue, 27 Jul 2021 08:30:48 -0400
Subject: [PATCH 15/15] add replace back

---
 lib/dry/configurable/settings.rb              |  8 +++++++
 .../dry/configurable/settings_spec.rb         | 23 +++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/lib/dry/configurable/settings.rb b/lib/dry/configurable/settings.rb
index cb081fc1..899809ec 100644
--- a/lib/dry/configurable/settings.rb
+++ b/lib/dry/configurable/settings.rb
@@ -23,6 +23,14 @@ def initialize(elements = EMPTY_ARRAY)
         initialize_elements(elements)
       end
 
+      def replace(settings)
+        ensure_arguments(settings)
+
+        settings.dup.each do |setting|
+          self << setting
+        end
+      end
+
       def merge!(settings)
         merge(settings).each do |setting|
           self << setting
diff --git a/spec/integration/dry/configurable/settings_spec.rb b/spec/integration/dry/configurable/settings_spec.rb
index b95d94a9..104595a2 100644
--- a/spec/integration/dry/configurable/settings_spec.rb
+++ b/spec/integration/dry/configurable/settings_spec.rb
@@ -10,6 +10,29 @@
       end
     end
 
+    context "with replace" do
+      let(:other_klass) do
+        Class.new do
+          extend Dry::Configurable
+        end
+      end
+
+      it "should replace nested fields" do
+        klass.setting :database do
+          setting :host, "localhost"
+        end
+
+        other_klass.setting :database do
+          setting :type, "postgresql"
+        end
+        other_klass._settings.replace(klass._settings)
+        expect(other_klass.config.database.host).to eql("localhost")
+        expect { other_klass.config.database.type }.to raise_error do |error|
+          expect(error.class).to eql(NoMethodError)
+        end
+      end
+    end
+
     context "with merge" do
       let(:other_klass) do
         Class.new do