diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..b4ea5ba
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,24 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+This format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## 0.1.2
+
+### Added
+
+- basic tests for a library
+
+### Changed
+
+- #ensure_<attribute>_may_transition_to! method now actually verifies that an attribute can transition to a new state.
+
+## 0.1.1
+
+### Added
+
+- Provide real authorts of this gem.
+
+## 0.1.0
+
+- Initial release
diff --git a/Gemfile.lock b/Gemfile.lock
index a1ea20d..0e710c7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,12 +1,18 @@
 PATH
   remote: .
   specs:
-    state_machine_enum (0.1.1)
-      activesupport (>= 6.0)
+    state_machine_enum (0.1.2)
+      activesupport (~> 7)
 
 GEM
   remote: https://rubygems.org/
   specs:
+    activemodel (7.1.3.3)
+      activesupport (= 7.1.3.3)
+    activerecord (7.1.3.3)
+      activemodel (= 7.1.3.3)
+      activesupport (= 7.1.3.3)
+      timeout (>= 0.4.0)
     activesupport (7.1.3.3)
       base64
       bigdecimal
@@ -28,6 +34,7 @@ GEM
     json (2.7.2)
     language_server-protocol (3.17.0.3)
     lint_roller (1.1.0)
+    mini_portile2 (2.8.7)
     minitest (5.23.1)
     mutex_m (0.2.0)
     parallel (1.24.0)
@@ -57,6 +64,9 @@ GEM
       rubocop (>= 1.48.1, < 2.0)
       rubocop-ast (>= 1.31.1, < 2.0)
     ruby-progressbar (1.13.0)
+    sqlite3 (1.7.3)
+      mini_portile2 (~> 2.8.0)
+    sqlite3 (1.7.3-arm64-darwin)
     standard (1.36.0)
       language_server-protocol (~> 3.17.0.2)
       lint_roller (~> 1.0)
@@ -70,6 +80,7 @@ GEM
       lint_roller (~> 1.1)
       rubocop-performance (~> 1.21.0)
     strscan (3.1.0)
+    timeout (0.4.1)
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
     unicode-display_width (2.5.0)
@@ -79,8 +90,10 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  activerecord (~> 7)
   minitest (~> 5.16)
   rake (~> 13.0)
+  sqlite3 (~> 1.4)
   standard (~> 1.3)
   state_machine_enum!
 
diff --git a/lib/state_machine_enum.rb b/lib/state_machine_enum.rb
index 88e0e20..03b3120 100644
--- a/lib/state_machine_enum.rb
+++ b/lib/state_machine_enum.rb
@@ -114,6 +114,7 @@ def state_machine_enum(attribute_name, **options_for_enum)
         define_method(:"ensure_#{attribute_name}_may_transition_to!") do |next_state|
           val = self[attribute_name]
           raise InvalidState, "#{attribute_name} already is #{val.inspect}" if next_state.to_s == val
+          raise InvalidState, "#{attribute_name} may not transition from #{val.inspect} to #{next_state.inspect}" unless collector.may_transition?(val, next_state)
         end
 
         define_method(:"#{attribute_name}_may_transition_to?") do |next_state|
diff --git a/lib/state_machine_enum/version.rb b/lib/state_machine_enum/version.rb
index fa74b91..b9ae0cd 100644
--- a/lib/state_machine_enum/version.rb
+++ b/lib/state_machine_enum/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module StateMachineEnum
-  VERSION = "0.1.1"
+  VERSION = "0.1.2"
 end
diff --git a/state_machine_enum.gemspec b/state_machine_enum.gemspec
index 9ace760..c4637d9 100644
--- a/state_machine_enum.gemspec
+++ b/state_machine_enum.gemspec
@@ -14,11 +14,9 @@ Gem::Specification.new do |spec|
   spec.license = "MIT"
   spec.required_ruby_version = ">= 3.0.0"
 
-  # spec.metadata["allowed_push_host"] = "TODO: Set to your gem server 'https://example.com'"
-
   spec.metadata["homepage_uri"] = spec.homepage
   spec.metadata["source_code_uri"] = "https://github.com/cheddar-me/state_machine_enum"
-  #spec.metadata["changelog_uri"] = "TODO: Put your gem's CHANGELOG.md URL here."
+  spec.metadata["changelog_uri"] = "https://github.com/cheddar-me/state_machine_enum/blob/main/CHANGELOG.md"
 
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
@@ -29,9 +27,9 @@ Gem::Specification.new do |spec|
         f.start_with?(*%w[bin/ test/ spec/ features/ .git .github appveyor Gemfile])
     end
   end
-  spec.bindir = "exe"
-  spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_dependency "activesupport", ">= 6.0"
+  spec.add_dependency "activesupport", "~> 7"
+  spec.add_development_dependency "sqlite3", "~> 1.4"
+  spec.add_development_dependency "activerecord", "~> 7"
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 18a5dd3..8a8c55e 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -4,3 +4,22 @@
 require "state_machine_enum"
 
 require "minitest/autorun"
+require "active_support"
+require "active_support/test_case"
+require "active_record"
+
+class ActiveSupport::TestCase
+  def setup
+    ActiveRecord::Migration.verbose = false
+    ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
+    ActiveRecord::Schema.define do
+      create_table :users, force: true do |t|
+        t.string :state, default: "registered"
+      end
+    end
+  end
+
+  def teardown
+    ActiveRecord::Base.connection.disconnect!
+  end
+end
diff --git a/test/test_state_machine_enum.rb b/test/test_state_machine_enum.rb
index c5c1dc2..1bf2456 100644
--- a/test/test_state_machine_enum.rb
+++ b/test/test_state_machine_enum.rb
@@ -2,12 +2,72 @@
 
 require "test_helper"
 
-class TestStateMachineEnum < Minitest::Test
-  def test_that_it_has_a_version_number
-    refute_nil ::StateMachineEnum::VERSION
+class TestStateMachineEnum < ActiveSupport::TestCase
+  class User < ActiveRecord::Base
+    include StateMachineEnum
+
+    state_machine_enum :state do |s|
+      s.permit_transition(:registered, :active)
+      s.permit_transition(:active, :banned)
+      s.permit_transition(:banned, :active)
+      s.permit_transition(:active, :deleted)
+    end
+  end
+
+  def test_state_transitions
+    u = User.create!
+
+    assert u.active!
+    assert u.banned!
+    assert u.active!
+    assert u.deleted!
+  end
+
+  def test_callbacks
+    u = User.create!
+
+    assert u.active!
+    error = assert_raises(ActiveRecord::RecordInvalid) { u.registered! }
+    assert_equal("Validation failed: State Invalid transition from active to registered", error.message)
+
+    error = assert_raises(ArgumentError) { u.update!(state: "missing") }
+    assert_equal("'missing' is not a valid state", error.message)
+  end
+
+  def test_ensure_state_may_transition_to!
+    u = User.create!(state: "active")
+
+    assert_nil u.ensure_state_may_transition_to!(:banned)
+
+    assert_raises(StateMachineEnum::InvalidState) { u.ensure_state_may_transition_to!("active") }
+    error = assert_raises(StateMachineEnum::InvalidState) { u.ensure_state_may_transition_to!(:active) }
+    assert_equal("state already is \"active\"", error.message)
+
+    error = assert_raises(StateMachineEnum::InvalidState) { u.ensure_state_may_transition_to!(:registered) }
+    assert_equal("state may not transition from \"active\" to :registered", error.message)
+  end
+
+  def test_ensure_state_one_of!
+    u = User.create!(state: "active")
+
+    assert_nil u.ensure_state_one_of!(:active, :banned)
+    assert_nil u.ensure_state_one_of!("active", "banned")
+
+    error = assert_raises(StateMachineEnum::InvalidState) { u.ensure_state_one_of!(:banned, :deleted) }
+    assert_equal("state must be one of [:banned, :deleted] but was \"active\"", error.message)
+
+    error = assert_raises(StateMachineEnum::InvalidState) { u.ensure_state_one_of!("banned", "deleted") }
+    assert_equal("state must be one of [\"banned\", \"deleted\"] but was \"active\"", error.message)
   end
 
-  def test_it_does_something_useful
-    assert false
+  def test_may_transition_to?
+    u = User.create!
+
+    assert u.active!
+
+    assert u.state_may_transition_to?(:banned)
+    assert u.state_may_transition_to?("banned")
+    refute u.state_may_transition_to?(:registered)
+    refute u.state_may_transition_to?(:missing)
   end
 end