diff --git a/.travis.yml b/.travis.yml
index 98c9853..19d978b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,7 @@ addons:
   postgresql: "9.6"
 services:
   - postgresql
+  - redis-server
 sudo: false
 language: ruby
 cache: bundler
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index cff0041..d505f4e 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -3,6 +3,12 @@ class ApplicationController < ActionController::Base
 
   private
 
+  def development_enabled?
+    Util::DevelopmentHelper.development_enabled?
+  end
+
+  helper_method :development_enabled?
+
   def raise_404(message: nil)
     raise ActionController::RoutingError, (message || 'Not Found')
   end
diff --git a/app/controllers/auth_controller.rb b/app/controllers/auth_controller.rb
deleted file mode 100644
index c804bd8..0000000
--- a/app/controllers/auth_controller.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-class AuthController < ApplicationController
-  layout false
-end
diff --git a/app/controllers/auth_tokens_controller.rb b/app/controllers/auth_tokens_controller.rb
index 36dbc1f..5c078f3 100644
--- a/app/controllers/auth_tokens_controller.rb
+++ b/app/controllers/auth_tokens_controller.rb
@@ -8,7 +8,7 @@ def destroy
   end
 
   def dev_login
-    raise_404 unless Rails.env.development?
+    raise_404 unless development_enabled?
 
     warden.logout
     authenticate!(:developer)
diff --git a/app/controllers/dev/base_controller.rb b/app/controllers/dev/base_controller.rb
index 44a0ac8..3772f91 100644
--- a/app/controllers/dev/base_controller.rb
+++ b/app/controllers/dev/base_controller.rb
@@ -7,7 +7,9 @@ class BaseController < UIController
     private
 
     def ensure_development
-      raise_404 unless Rails.env.development?
+      return if development_enabled?
+
+      raise_404
     end
   end
-end
\ No newline at end of file
+end
diff --git a/app/controllers/ledgers/test_controller.rb b/app/controllers/ledgers/test_controller.rb
new file mode 100644
index 0000000..f1715fa
--- /dev/null
+++ b/app/controllers/ledgers/test_controller.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+module Ledgers
+  class TestController < DashboardBaseController
+    before_action :ensure_test_env
+    before_action :set_ledger, only: %i[show]
+
+    private
+
+    def ensure_test_env
+      return if Rails.env.test?
+
+      raise_404
+    end
+
+    def set_ledger
+      @ledger = current_organization
+                .ledgers(kind: LedgerSync.adaptors.test.root_key.to_s)
+                .object
+                .find(params[:id])
+                .decorate
+    end
+  end
+end
diff --git a/app/controllers/ledgers_controller.rb b/app/controllers/ledgers_controller.rb
index 357e147..4802729 100644
--- a/app/controllers/ledgers_controller.rb
+++ b/app/controllers/ledgers_controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LedgersController < DashboardBaseController
   before_action :set_ledger, only: :show
 
@@ -10,4 +12,4 @@ def show
   def set_ledger
     @ledger = Ledger.find(params[:id]).decorate
   end
-end
\ No newline at end of file
+end
diff --git a/app/decorators/ledger_decorator.rb b/app/decorators/ledger_decorator.rb
index e1c5253..8004902 100644
--- a/app/decorators/ledger_decorator.rb
+++ b/app/decorators/ledger_decorator.rb
@@ -12,9 +12,12 @@ def name
   end
 
   def show_path
-    case kind
+    case kind.to_s
     when Util::QuickBooksOnline::KEY
       r.ledgers_quickbooks_online_path(self)
+    when LedgerSync.adaptors.test.root_key.to_s
+      raise NotImplementedError unless Rails.env.test?
+      r.ledgers_test_path(self)
     else
       raise NotImplementedError
     end
diff --git a/app/errors/routing_error.rb b/app/errors/routing_error.rb
deleted file mode 100644
index d5c47f8..0000000
--- a/app/errors/routing_error.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-class RoutingError < APIError
-  def initialize
-    super(
-      "Invalid route. Please check that the path is typed correctly.",
-      type: 'routing_error',
-      status: 404
-    )
-  end
-end
diff --git a/app/jobs/event_jobs.rb b/app/jobs/event_jobs.rb
index 7ce276e..b9b293e 100644
--- a/app/jobs/event_jobs.rb
+++ b/app/jobs/event_jobs.rb
@@ -18,8 +18,10 @@ def perform(data, event_object_type, event_object_id, organization_id, type)
 
   class Emit < ApplicationJob
     def perform(event_id)
+      event = Event.find(event_id)
+
       Forms::Events::Emit.new(
-        event: Event.find(event_id)
+        event: event
       ).save.raise_if_error
     end
   end
diff --git a/app/lib/acl.rb b/app/lib/acl.rb
deleted file mode 100644
index a0754c3..0000000
--- a/app/lib/acl.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-# TODO: Remove before launch.  Here for convenience.
-ACL = LedgerSync
\ No newline at end of file
diff --git a/app/lib/forms/events/emit.rb b/app/lib/forms/events/emit.rb
index c4f0262..da76ebb 100644
--- a/app/lib/forms/events/emit.rb
+++ b/app/lib/forms/events/emit.rb
@@ -38,9 +38,22 @@ def emit
         response = HTTP.headers(headers).post(url, body: serialized_event_json_string)
         status = response.status
 
-        return failure(status.inspect) unless status.success?
+        return success(event) if status.success?
 
-        success(event)
+        notify_provider
+        failure(status.inspect)
+      end
+
+      def notify_provider
+        redis = Redis.new
+        key = 'webhooks/provider_last_notified_at'
+
+        provider_last_notified_at = redis.get(key)
+
+        return if provider_last_notified_at.present? && (Time.zone.now - Time.parse(provider_last_notified_at)) < 24.hours
+
+        redis.set(key, Time.zone.now.to_s)
+        DeveloperMailer.webhook_failure(event.id).deliver_later
       end
 
       def serialized_event_json_string
diff --git a/app/lib/util/development_helper.rb b/app/lib/util/development_helper.rb
new file mode 100644
index 0000000..bc4be41
--- /dev/null
+++ b/app/lib/util/development_helper.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+module Util
+  module DevelopmentHelper
+    def self.development_enabled?
+      Rails.env.development? || (Rails.env.test? && ENV['DEVELOPMENT'] == 'true')
+    end
+  end
+end
diff --git a/app/mailers/application_mailer.rb b/app/mailers/application_mailer.rb
index 286b223..56349a7 100644
--- a/app/mailers/application_mailer.rb
+++ b/app/mailers/application_mailer.rb
@@ -1,4 +1,4 @@
 class ApplicationMailer < ActionMailer::Base
-  default from: 'from@example.com'
+  default from: Settings.mailer.from_email
   layout 'mailer'
 end
diff --git a/app/mailers/developer_mailer.rb b/app/mailers/developer_mailer.rb
new file mode 100644
index 0000000..227c951
--- /dev/null
+++ b/app/mailers/developer_mailer.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class DeveloperMailer < ApplicationMailer
+  def webhook_failure(event_id)
+    @event = Event.find(event_id)
+    mail(
+      subject: "Webhook failure at #{Time.zone.now}",
+      to: Settings.application.developer_email
+    )
+  end
+end
diff --git a/app/views/developer_mailer/webhook_failure.html.haml b/app/views/developer_mailer/webhook_failure.html.haml
new file mode 100644
index 0000000..d6b9588
--- /dev/null
+++ b/app/views/developer_mailer/webhook_failure.html.haml
@@ -0,0 +1,4 @@
+%h1 Webhook Failure
+
+%p
+  Event ID: #{@event.id}
diff --git a/app/views/layouts/_nav.html.haml b/app/views/layouts/_nav.html.haml
index 9d01423..b155cb9 100644
--- a/app/views/layouts/_nav.html.haml
+++ b/app/views/layouts/_nav.html.haml
@@ -25,7 +25,8 @@
       %li.nav-item.mr-3
         = link_to '#', class: 'nav-link' do
           Log In
-      - if Rails.env.development?
-        %li.nav-item.mr-3
-          = link_to dev_login_path, class: 'btn btn-danger' do
-            Dev Log In
+- if development_enabled?
+  %ul
+    %li.nav-item.mr-3
+      = link_to dev_login_path, class: 'btn btn-danger' do
+        Dev Log In
diff --git a/app/views/layouts/mailer.html.erb b/app/views/layouts/mailer.html.erb
deleted file mode 100644
index cbd34d2..0000000
--- a/app/views/layouts/mailer.html.erb
+++ /dev/null
@@ -1,13 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <head>
-    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
-    <style>
-      /* Email styles need to be inline */
-    </style>
-  </head>
-
-  <body>
-    <%= yield %>
-  </body>
-</html>
diff --git a/app/views/layouts/mailer.html.haml b/app/views/layouts/mailer.html.haml
new file mode 100644
index 0000000..cbf6b8e
--- /dev/null
+++ b/app/views/layouts/mailer.html.haml
@@ -0,0 +1,8 @@
+!!!
+%html
+  %head
+    %meta{:content => "text/html; charset=utf-8", "http-equiv" => "Content-Type"}/
+    :css
+      /* Email styles need to be inline */
+  %body
+    = yield
diff --git a/app/views/layouts/mailer.text.erb b/app/views/layouts/mailer.text.erb
deleted file mode 100644
index 37f0bdd..0000000
--- a/app/views/layouts/mailer.text.erb
+++ /dev/null
@@ -1 +0,0 @@
-<%= yield %>
diff --git a/app/views/ledgers/test/show.html.haml b/app/views/ledgers/test/show.html.haml
new file mode 100644
index 0000000..a4679b1
--- /dev/null
+++ b/app/views/ledgers/test/show.html.haml
@@ -0,0 +1,2 @@
+.container
+  %h1 Test Adaptor - You made it!
\ No newline at end of file
diff --git a/config/initializers/config.rb b/config/initializers/config.rb
index cf2f79a..2461115 100644
--- a/config/initializers/config.rb
+++ b/config/initializers/config.rb
@@ -79,6 +79,7 @@
     end
 
     required(:application).schema do
+      required(:developer_email).filled(:str?)
       required(:host_port).maybe(:int?)
       required(:host_url).filled(:str?)
       required(:login_url).maybe(:str?)
@@ -102,6 +103,7 @@
     required(:mailer).filled do
       schema do
         required(:delivery_method).filled(:str?)
+        required(:from_email).filled(:str?)
         optional(:smtp).filled do
           schema do
             required(:address).filled(:str?)
diff --git a/config/initializers/warden.rb b/config/initializers/warden.rb
index 5567223..2f76462 100644
--- a/config/initializers/warden.rb
+++ b/config/initializers/warden.rb
@@ -18,7 +18,7 @@ def result
 
 Warden::Strategies.add(:developer) do
   def valid?
-    raise 'Invalid strategy' unless Rails.env.development?
+    raise 'Invalid strategy' unless Util::DevelopmentHelper.development_enabled?
 
     true
   end
diff --git a/config/routes.rb b/config/routes.rb
index 981a11f..9b63dc9 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -98,6 +98,7 @@
     resources :ledgers, only: %i[index show]
 
     namespace :ledgers do
+      resources :tests, path: :test, only: %i[show], controller: :test
       resources :quickbooks_onlines, path: :quickbooks_online, only: %i[destroy new show update], controller: :quickbooks_online do
         collection do
           get :callback
diff --git a/config/settings.yml b/config/settings.yml
index 51ece03..08d04a4 100644
--- a/config/settings.yml
+++ b/config/settings.yml
@@ -20,9 +20,10 @@ api:
   root_secret_key:                  # required: The API key your application will use to send data to the Ledger Sync App
 
 application:
-  login_url:                        # required: the url where users will be redirect if authentication is required
+  developer_email:                  # required: email for developer notifications (e.g. webhook failure)
   host_port:                        # optional
   host_url:                         # required: where this app is hosted (e.g. `sync.example.com`)
+  login_url:                        # required: the url where users will be redirect if authentication is required
   name: 'Ledger Sync'               # required: usually your company name
   theme: modern_treasury            # optional: Name of theme in app/assets/stylesheets/themes
   webhooks:
@@ -39,6 +40,7 @@ customization:
 mailer:
   delivery_method:                  # required: letter_opener (only in development), smtp, test (only in test)
   disable_email_to_users: false     # optional
+  from_email:                       # required: email address for replies
   # smtp:                           # required if delivery_method=smtp
   #   address:                      # - required
   #   authentication:               # - required
diff --git a/config/settings/development.yml b/config/settings/development.yml
index 489e494..a44fe8a 100644
--- a/config/settings/development.yml
+++ b/config/settings/development.yml
@@ -1,4 +1,5 @@
 application:
+  developer_email: me@example.com
   host_url: 'localhost'
   host_port: 3000
 
@@ -7,3 +8,4 @@ dev:
 
 mailer:
   delivery_method: 'letter_opener'
+  from_email: 'no-reply-dev@example.com'
diff --git a/config/settings/test.yml b/config/settings/test.yml
index bfc92e5..d2c040b 100644
--- a/config/settings/test.yml
+++ b/config/settings/test.yml
@@ -9,10 +9,12 @@ add_ons:
 api:
   root_secret_key: 'test_api_key'
 application:
+  developer_email: test@example.com
   host_url: 'lvh.me'
   host_port: 3000
   webhooks:
     key: 'foobarbaz'
-    url: 'http://lvh.me'
+    url: 'http://127.0.0.1:3000'
 mailer:
-  delivery_method: 'test'
\ No newline at end of file
+  delivery_method: 'test'
+  from_email: 'no-reply-test@example.com'
\ No newline at end of file
diff --git a/spec/decorators/ledger_decorator_spec.rb b/spec/decorators/ledger_decorator_spec.rb
index d3139e3..030a726 100644
--- a/spec/decorators/ledger_decorator_spec.rb
+++ b/spec/decorators/ledger_decorator_spec.rb
@@ -13,6 +13,11 @@
 
     it do
       ledger = create(:ledger, :test)
+      expect(ledger.decorate.show_path).to eq(r.ledgers_test_path(ledger))
+    end
+
+    it do
+      ledger = create(:ledger, kind: :asdf)
       expect { ledger.decorate.show_path }.to raise_error(NotImplementedError)
     end
   end
diff --git a/spec/features/dev/authentication_spec.rb b/spec/features/dev/authentication_spec.rb
new file mode 100644
index 0000000..4e7c27d
--- /dev/null
+++ b/spec/features/dev/authentication_spec.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+require 'formify/spec_helpers'
+
+describe 'dev/authentication', js: true, type: :feature do
+  def expect_authorized
+    expect_content('authorized')
+  end
+
+  def expect_unauthorized
+    expect_content('unauthorized')
+  end
+
+  it do
+    visit r.root_path
+    expect_no_content :invisible, 'Dev Log In'
+    visit r.auth_tokens_path
+    expect_unauthorized
+  end
+
+  it do
+    ClimateControl.modify(DEVELOPMENT: 'true') do
+      visit r.root_path
+      click_on 'Dev Log In'
+      visit r.auth_tokens_path
+      expect_authorized
+    end
+  end
+end
diff --git a/spec/features/dev/home_spec.rb b/spec/features/dev/home_spec.rb
new file mode 100644
index 0000000..a68df67
--- /dev/null
+++ b/spec/features/dev/home_spec.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+require 'formify/spec_helpers'
+
+describe 'dev/home', js: true, type: :feature do
+  it do
+    ClimateControl.modify(DEVELOPMENT: 'true') do
+      visit r.root_path
+      click_on 'Dev Log In'
+      visit r.dev_path
+      expect_content 'Create Sync'
+    end
+  end
+end
diff --git a/spec/features/dev/syncs_spec.rb b/spec/features/dev/syncs_spec.rb
new file mode 100644
index 0000000..a0f8276
--- /dev/null
+++ b/spec/features/dev/syncs_spec.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe 'sync_ledgers/create', js: true, type: :feature do
+  xit do
+    login
+    expect { visit r.new_dev_sync_path }.to raise_error(ActionController::RoutingError)
+  end
+
+  it do
+    ClimateControl.modify(DEVELOPMENT: 'true') do
+      login(FactoryBot.create(:user, :admin))
+      visit r.new_dev_sync_path
+      expect_content 'Create Sync'
+      expect do
+        click_on 'Send'
+        expect_content 'Operation'
+      end.to change(Sync, :count).from(0).to(1)
+    end
+  end
+end
diff --git a/spec/features/ledgers_spec.rb b/spec/features/ledgers_spec.rb
new file mode 100644
index 0000000..41a4276
--- /dev/null
+++ b/spec/features/ledgers_spec.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe 'ledgers/test', js: true, type: :feature do
+  let(:ledger) { FactoryBot.create(:ledger) }
+
+  it do
+    login
+    visit r.ledgers_path
+    expect_content 'Ledgers'
+    expect_content 'Connect QuickBooks'
+  end
+
+  it do
+    login
+    ledger
+    visit r.ledgers_path
+    expect_content 'Test Ledger Adaptor'
+    click_on 'View'
+    expect_content 'You made it!'
+    expect_path ledger.decorate.show_path
+  end
+end
diff --git a/spec/fixtures/developer/webhook_failure b/spec/fixtures/developer/webhook_failure
new file mode 100644
index 0000000..93ff7c6
--- /dev/null
+++ b/spec/fixtures/developer/webhook_failure
@@ -0,0 +1,3 @@
+Developer#webhook_failure
+
+Hi, find me in app/views/developer/webhook_failure
diff --git a/spec/jobs/event_jobs/create_and_emit_spec.rb b/spec/jobs/event_jobs/create_and_emit_spec.rb
index df244e3..ec28ae4 100644
--- a/spec/jobs/event_jobs/create_and_emit_spec.rb
+++ b/spec/jobs/event_jobs/create_and_emit_spec.rb
@@ -14,6 +14,13 @@
   let(:perform) { Sidekiq::Testing.inline! { described_class.perform_async(*args) } }
   let(:result) { described_class.new.perform(*args) }
 
+  before do
+    stub_request(
+      :post,
+      Settings.application.webhooks.url
+    )
+  end
+
   it { expect(result).to be_success }
   it { expect { result.value }.to change(EventJobs::Emit.jobs, :count).from(0).to(1) }
 end
diff --git a/spec/lib/util/webhook_signer_spec.rb b/spec/lib/util/webhook_signer_spec.rb
index 20b256f..1a6af6d 100644
--- a/spec/lib/util/webhook_signer_spec.rb
+++ b/spec/lib/util/webhook_signer_spec.rb
@@ -24,12 +24,12 @@
       end
     end
 
-    it { expect { subject }.to raise_error }
+    it { expect { subject }.to raise_error(RuntimeError, 'Missing Settings.application.webhooks.key') }
   end
 
   context 'without data as string' do
     let(:data) { {} }
 
-    it { expect { subject }.to raise_error }
+    it { expect { subject }.to raise_error(RuntimeError, 'data must be a string') }
   end
 end
diff --git a/spec/mailers/developer_spec.rb b/spec/mailers/developer_spec.rb
new file mode 100644
index 0000000..d43aaa1
--- /dev/null
+++ b/spec/mailers/developer_spec.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe DeveloperMailer, type: :mailer do
+  describe 'webhook_failure' do
+    let(:event) { FactoryBot.create(:event) }
+    let(:mail) { described_class.webhook_failure(event.id) }
+
+    it 'renders the headers' do
+      expect(mail.subject).to include('Webhook failure at ')
+      expect(mail.to).to eq(['test@example.com'])
+      expect(mail.from).to eq(['no-reply-test@example.com'])
+    end
+
+    it 'renders the body' do
+      expect(mail.body.encoded).to include("Event ID: #{event.id}")
+    end
+  end
+end
diff --git a/spec/mailers/previews/developer_preview.rb b/spec/mailers/previews/developer_preview.rb
new file mode 100644
index 0000000..7825b08
--- /dev/null
+++ b/spec/mailers/previews/developer_preview.rb
@@ -0,0 +1,9 @@
+# Preview all emails at http://localhost:3000/rails/mailers/developer
+class DeveloperPreview < ActionMailer::Preview
+
+  # Preview this email at http://localhost:3000/rails/mailers/developer/webhook_failure
+  def webhook_failure
+    DeveloperMailer.webhook_failure
+  end
+
+end
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index 6dd2e54..0d9877f 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -13,6 +13,7 @@
 )
 
 SimpleCov.start do
+  add_filter '/channels'
   add_filter '/config/initializers'
   add_filter '/spec/support'
 end
diff --git a/spec/support/feature_helpers.rb b/spec/support/feature_helpers.rb
index 70f8632..ece2e56 100644
--- a/spec/support/feature_helpers.rb
+++ b/spec/support/feature_helpers.rb
@@ -31,10 +31,16 @@ def expect_404
   #   end
   # end
 
-  def expect_content(content)
-    raise 'content cannot be blank' if content.blank?
+  def expect_content(*args, **keywords)
+    raise 'content cannot be blank' if args.last.blank?
 
-    expect(page).to have_content(content, wait: 10)
+    expect(page).to have_content(*args, wait: 10, **keywords)
+  end
+
+  def expect_no_content(*args, **keywords)
+    raise 'content cannot be blank' if args.last.blank?
+
+    expect(page).not_to have_content(*args, wait: 10, **keywords)
   end
 
   def expect_count(selector, num = 1)