diff --git a/README.md b/README.md
index 0644bea..46fb34b 100644
--- a/README.md
+++ b/README.md
@@ -49,6 +49,8 @@ Development
 
 After checking out the repo, run `bin/setup` to install dependencies. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
 
+To test this gem, run `bundle exec rake test`.
+
 To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
 
 Contributing
diff --git a/Rakefile b/Rakefile
index 43022f7..d433a1e 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,2 +1,10 @@
 require "bundler/gem_tasks"
-task :default => :spec
+require "rake/testtask"
+
+Rake::TestTask.new(:test) do |t|
+  t.libs << "test"
+  t.libs << "lib"
+  t.test_files = FileList["test/**/*_test.rb"]
+end
+
+task :default => :test
diff --git a/faker-okinawa.gemspec b/faker-okinawa.gemspec
index b80a007..c409727 100644
--- a/faker-okinawa.gemspec
+++ b/faker-okinawa.gemspec
@@ -20,4 +20,5 @@ Gem::Specification.new do |spec|
 
   spec.add_development_dependency "bundler", "~> 1.11"
   spec.add_development_dependency "rake", "~> 10.0"
+  spec.add_development_dependency "minitest", "~> 5.14"
 end
diff --git a/test/faker/okinawa/address_test.rb b/test/faker/okinawa/address_test.rb
new file mode 100644
index 0000000..d9727f0
--- /dev/null
+++ b/test/faker/okinawa/address_test.rb
@@ -0,0 +1,23 @@
+require 'test_helper'
+
+class AddressTest < Faker::Okinawa::TestCase
+  def setup
+    @tester = Faker::Okinawa::Address
+  end
+
+  def test_city
+    assert word?(@tester.city)
+  end
+
+  def test_district
+    assert word?(@tester.district)
+  end
+
+  def test_island
+    assert word?(@tester.island)
+  end
+
+  def test_park
+    assert word?(@tester.park)
+  end
+end
diff --git a/test/faker/okinawa/awamori_test.rb b/test/faker/okinawa/awamori_test.rb
new file mode 100644
index 0000000..5d2c50b
--- /dev/null
+++ b/test/faker/okinawa/awamori_test.rb
@@ -0,0 +1,11 @@
+require 'test_helper'
+
+class AwamoriTest < Faker::Okinawa::TestCase
+  def setup
+    @tester = Faker::Okinawa::Awamori
+  end
+
+  def test_name
+    assert word?(@tester.name)
+  end
+end
diff --git a/test/faker/okinawa/base_test.rb b/test/faker/okinawa/base_test.rb
new file mode 100644
index 0000000..1b1d5aa
--- /dev/null
+++ b/test/faker/okinawa/base_test.rb
@@ -0,0 +1,11 @@
+require 'test_helper'
+
+class BaseTest < Faker::Okinawa::TestCase
+  def setup
+    @tester = Faker::Okinawa::Base
+  end
+
+  def test_name
+    assert word?(@tester.name)
+  end
+end
diff --git a/test/faker/okinawa/fish_test.rb b/test/faker/okinawa/fish_test.rb
new file mode 100644
index 0000000..75c24a5
--- /dev/null
+++ b/test/faker/okinawa/fish_test.rb
@@ -0,0 +1,11 @@
+require 'test_helper'
+
+class FishTest < Faker::Okinawa::TestCase
+  def setup
+    @tester = Faker::Okinawa::Fish
+  end
+
+  def test_name
+    assert word?(@tester.name)
+  end
+end
diff --git a/test/faker/okinawa/food_test.rb b/test/faker/okinawa/food_test.rb
new file mode 100644
index 0000000..f8039f2
--- /dev/null
+++ b/test/faker/okinawa/food_test.rb
@@ -0,0 +1,11 @@
+require 'test_helper'
+
+class FoodTest < Faker::Okinawa::TestCase
+  def setup
+    @tester = Faker::Okinawa::Food
+  end
+
+  def test_name
+    assert word?(@tester.name)
+  end
+end
diff --git a/test/faker/okinawa/name_test.rb b/test/faker/okinawa/name_test.rb
new file mode 100644
index 0000000..16a6a6a
--- /dev/null
+++ b/test/faker/okinawa/name_test.rb
@@ -0,0 +1,11 @@
+require 'test_helper'
+
+class NameTest < Faker::Okinawa::TestCase
+  def setup
+    @tester = Faker::Okinawa::Name
+  end
+
+  def test_last_name
+    assert word?(@tester.last_name)
+  end
+end
diff --git a/test/faker/okinawa/odic_test.rb b/test/faker/okinawa/odic_test.rb
new file mode 100644
index 0000000..175e76e
--- /dev/null
+++ b/test/faker/okinawa/odic_test.rb
@@ -0,0 +1,77 @@
+# coding: utf-8
+require 'test_helper'
+
+class OdicTest < Faker::Okinawa::TestCase
+
+  def test_normal
+    odic = Faker::Okinawa::Odic.new(dic_path("normal_entries.dic"))
+
+    assert_equal Faker::Okinawa::Odic::Entry.new("まちかじ", "松風", "普通名詞", "菓子"),
+                 odic.entries[0]
+  end
+
+  def test_comment
+    odic = Faker::Okinawa::Odic.new(dic_path("comment.dic"))
+
+    # ignore comment line
+    assert_equal 23, File.readlines(dic_path("comment.dic"), encoding: 'utf-8').length
+    assert_equal  5, odic.entries.size
+
+    # tail comment
+    assert_equal "picked up",      odic.entries[0].comment
+    assert                        !odic.entries[1].comment
+
+    # trivial comment rules
+    assert_equal "亜",             odic.entries[2].word_class
+    assert_equal "コメント１",     odic.entries[2].comment
+    assert_equal "亜#",            odic.entries[3].word_class
+    assert                        !odic.entries[3].comment   
+    assert_equal "亜#コメント３",  odic.entries[4].word_class
+    assert                        !odic.entries[4].comment   
+  end
+
+  def test_empty
+    odic = Faker::Okinawa::Odic.new(dic_path("empty.dic"))
+    assert_equal 0, odic.entries.size
+  end
+
+  def test_entry_from_entry_line
+    # match ENTRY_WITH_COMMENT_REGEXP
+    entry = Faker::Okinawa::Odic::Entry.from_entry_line('1 2 3 #4')
+    assert_equal "1",  entry.phonate
+    assert_equal "2",  entry.word
+    assert_equal "3",  entry.word_class
+    assert_equal "4",  entry.comment
+
+    # match ENTRY_WITHOUT_COMMENT_REGEXP
+    entry = Faker::Okinawa::Odic::Entry.from_entry_line('1 2 3')
+    assert_equal "1",  entry.phonate
+    assert_equal "2",  entry.word
+    assert_equal "3",  entry.word_class
+    assert            !entry.comment
+
+    # doesn't match both regex(ENTRY_WITH_COMMENT_REGEXP, ENTRY_WITHOUT_COMMENT_REGEXP)
+    entry = Faker::Okinawa::Odic::Entry.from_entry_line('')
+    assert            !entry
+  end
+
+  def test_entry_valid?
+    # length(phonate: 40)
+    assert   !Faker::Okinawa::Odic::Entry.new('あ' * 40, 'い' * 63, 'う', nil).valid?
+    # length(word:    64)    
+    assert   !Faker::Okinawa::Odic::Entry.new('あ' * 39, 'い' * 64, 'う', nil).valid?
+
+    # character type(:phonate)
+    assert   !Faker::Okinawa::Odic::Entry.new('亜',      'い',      'う', nil).valid?
+    # character type(:word)
+    " \t\",#".each_char do |char|      
+      assert !Faker::Okinawa::Odic::Entry.new('あ',       char,     'う', nil).valid?
+    end
+  end
+
+  private
+
+    def dic_path(dic_name)
+      File.expand_path("../../fixtures/" + dic_name, __dir__)
+    end
+end
diff --git a/test/faker/okinawa/school_test.rb b/test/faker/okinawa/school_test.rb
new file mode 100644
index 0000000..1ccde65
--- /dev/null
+++ b/test/faker/okinawa/school_test.rb
@@ -0,0 +1,11 @@
+require 'test_helper'
+
+class SchoolTest < Faker::Okinawa::TestCase
+  def setup
+    @tester = Faker::Okinawa::School
+  end
+
+  def test_name
+    assert word?(@tester.name)
+  end
+end
diff --git a/test/faker/okinawa_test.rb b/test/faker/okinawa_test.rb
new file mode 100644
index 0000000..f9fc968
--- /dev/null
+++ b/test/faker/okinawa_test.rb
@@ -0,0 +1,7 @@
+require "test_helper"
+
+class FakerOkinawaTest < Faker::Okinawa::TestCase
+  def test_that_it_has_a_version_number
+    refute_nil Faker::Okinawa::VERSION
+  end
+end
diff --git a/test/fixtures/comment.dic b/test/fixtures/comment.dic
new file mode 100644
index 0000000..12a081d
--- /dev/null
+++ b/test/fixtures/comment.dic
@@ -0,0 +1,23 @@
+# This sample dic file describes a blank line, a comment line and a tail
+# comment
+#
+# A blank line is below.  ... very void. :-)
+
+# A comment line is me. It starts '#' or space.
+ So I am a comment line too.
+# These blank and comment lines are ignored.
+
+# A tail comment is below.  You can write a comment at tail of entry.  a tail
+# comment starts with/without '#'.  The former is picked up.  The latter is
+# ignored.
+あ	ア	亜	# picked up
+あ	ア	亜	ignored
+
+### Trivial rules for a tail comment.  It depend on spaces around '#'.
+
+# valid entry: word_class: "亜",  comment: "コメント１"
+あ	ア	亜 #コメント１
+# valid entry: word_class: "亜#", comment: nil
+あ	ア	亜# コメント２
+# valid entry: word_class: "亜#コメント３", comment: nil
+あ	ア	亜#コメント３
diff --git a/test/fixtures/empty.dic b/test/fixtures/empty.dic
new file mode 100644
index 0000000..e69de29
diff --git a/test/fixtures/normal_entries.dic b/test/fixtures/normal_entries.dic
new file mode 100644
index 0000000..681060b
--- /dev/null
+++ b/test/fixtures/normal_entries.dic
@@ -0,0 +1,2 @@
+#phonate	word	word_class	comment
+まちかじ	松風	普通名詞	# 菓子
diff --git a/test/helper_test.rb b/test/helper_test.rb
new file mode 100644
index 0000000..51a5c82
--- /dev/null
+++ b/test/helper_test.rb
@@ -0,0 +1,13 @@
+# coding: utf-8
+require "test_helper"
+
+class HelperTest < Faker::Okinawa::TestCase
+  def test_word?
+    assert  word?("English")
+    assert  word?("日本語")
+
+    assert !word?(""),               "should at least one character"
+    assert !word?("Boy meets girl"), "should not contain any spaces"
+    assert !word?(" "),              "should not spaces"
+  end
+end
diff --git a/test/test_helper.rb b/test/test_helper.rb
new file mode 100644
index 0000000..a92bc55
--- /dev/null
+++ b/test/test_helper.rb
@@ -0,0 +1,8 @@
+require "faker/okinawa"
+require "minitest/autorun"
+
+class Faker::Okinawa::TestCase < MiniTest::Test
+  def word?(str)
+    str.class == String && str.match(/^[^ \t\n]+$/)
+  end
+end