steepによる型チェックを修正してCIに組み込んだ

- `Gimei.addresses`の戻り値の型がおかしかったので直した
- Romajiの型がないので必要なものだけ定義した
- Array#sampleの戻り値にnilが含まれるためにエラーになっていたのをtype assertionを利用して解決した
  - ref: [steep/guides/src/nil-optional/nil-optional.md at master · soutaro/steep](https://github.com/soutaro/steep/blob/master/guides/src/nil-optional/nil-optional.md#handling-unwanted-nils)

- 次の2つのエラーは [`steep check` uses wrong context for `#define_method` in a singleton · Issue #380 · soutaro/steep](soutaro/steep#380
  - 実装側を変更することで対応した
  - 型のために実装を変えるのはあまりやりたくはないのだけど、define_methodよりclass_evalのほうが速いので許容した

```
lib/gimei.rb:44:13: [error] Unexpected positional argument
│ Diagnostic ID: Ruby::UnexpectedPositionalArgument
│
└         name(gender).public_send(method_name)
               ~~~~~~

lib/gimei/name.rb:19:12: [error] Unexpected positional argument
│ Diagnostic ID: Ruby::UnexpectedPositionalArgument
│
└         new(gender).public_send(method_name)
              ~~~~~~
```

- 次の2つのエラーは特異クラスに`extend Forwardable`する方法が現状ないため無視するようにした

```

lib/gimei.rb:27:4: [error] Type `singleton(::Class)` does not have method `def_delegators`
│ Diagnostic ID: Ruby::NoMethod
│
└     def_delegators 'Gimei::Name', :male, :female
      ~~~~~~~~~~~~~~

lib/gimei.rb:28:4: [error] Type `singleton(::Class)` does not have method `def_delegators`
│ Diagnostic ID: Ruby::NoMethod
│
└     def_delegators :address, :prefecture, :city, :town
      ~~~~~~~~~~~~~~
```

- `Gimei.names`と`@names`はsteepに期待通りに解釈させる方法が見つからなかったのでひとまずuntypedのままにしておく

.github/workflows/test.yml

@@ -32,7 +32,9 @@ jobs:
         with:
           ruby-version: ${{ matrix.ruby-version }}
           bundler-cache: true
-
+      - name: Run type check
+        run: bundle exec steep check --with-expectations
+        continue-on-error: ${{ matrix.allow_failures == 'true' }}
       - name: Run test
         run: |
           set -xe

Gemfile

@@ -3,3 +3,4 @@ source 'https://rubygems.org'
 # Specify your gem's dependencies in gimei.gemspec
 gemspec
 gem 'simplecov', require: false
+gem 'steep', require: false

Steepfile

@@ -0,0 +1,13 @@
+D = Steep::Diagnostic
+
+target :lib do
+  signature "sig"
+
+  check "lib"
+
+  library "forwardable"
+  library "yaml"
+
+  configure_code_diagnostics(D::Ruby.strict)
+end
+

lib/gimei.rb

@@ -9,7 +9,7 @@
 class Gimei
   extend Forwardable
 
-  GENDERS = [:male, :female].freeze
+  GENDERS = [:male, :female].freeze #: [:male, :female]
 
   def_delegators :@name,
                  :first, :last, :gender,
@@ -40,9 +40,11 @@ def addresses
     end
 
     %i[kanji hiragana katakana romaji first last family given].each do |method_name|
-      define_method(method_name) do |gender = nil|
-        name(gender).public_send(method_name)
-      end
+      class_eval(<<~METHOD, __FILE__, __LINE__ + 1)
+        def #{method_name}(gender = nil)
+          new(gender).#{method_name}
+        end
+       METHOD
     end
 
     def address

lib/gimei/address.rb

@@ -43,7 +43,7 @@ def romaji
     end
 
     def initialize
-      @prefectures = Gimei.addresses['addresses']['prefecture'].sample(random: Gimei.config.rng)
+      @prefectures = Gimei.addresses['addresses']['prefecture'].sample(random: Gimei.config.rng) #: [String, String, String]
     end
 
     alias_method :to_s, :kanji
@@ -67,7 +67,7 @@ def romaji
     end
 
     def initialize
-      @cities = Gimei.addresses['addresses']['city'].sample(random: Gimei.config.rng)
+      @cities = Gimei.addresses['addresses']['city'].sample(random: Gimei.config.rng) #: [String, String, String]
     end
 
     alias_method :to_s, :kanji
@@ -91,7 +91,7 @@ def romaji
     end
 
     def initialize
-      @towns = Gimei.addresses['addresses']['town'].sample(random: Gimei.config.rng)
+      @towns = Gimei.addresses['addresses']['town'].sample(random: Gimei.config.rng) #: [String, String, String]
     end
 
     alias_method :to_s, :kanji

lib/gimei/name.rb

@@ -15,14 +15,16 @@ def female
     end
 
     %i[kanji hiragana katakana romaji first last family given].each do |method_name|
-      define_method(method_name) do |gender = nil|
-        new(gender).public_send(method_name)
-      end
+      class_eval(<<~METHOD, __FILE__, __LINE__ + 1)
+        def #{method_name}(gender = nil)
+          new(gender).#{method_name}
+        end
+      METHOD
     end
   end
 
   def initialize(gender = nil)
-    @gender = gender || Gimei::GENDERS.sample(random: Gimei.config.rng)
+    @gender = gender || Gimei::GENDERS.sample(random: Gimei.config.rng) #: :male | :female
     @first = First.new @gender
     @last = Last.new
   end
@@ -71,7 +73,7 @@ def female
     def_delegators :@name, :kanji, :hiragana, :katakana, :to_s, :romaji
 
     def initialize(gender = nil)
-      @gender = gender || Gimei::GENDERS.sample(random: Gimei.config.rng)
+      @gender = gender || Gimei::GENDERS.sample(random: Gimei.config.rng) #: :male | :female
       @name = NameWord.new(Gimei.names['first_name'][@gender.to_s].sample(random: Gimei.config.rng))
     end
 
@@ -89,7 +91,8 @@ class Last
     def_delegators :@name, :kanji, :hiragana, :katakana, :to_s, :romaji
 
     def initialize
-      @name = NameWord.new(Gimei.names['last_name'].sample(random: Gimei.config.rng))
+      name = Gimei.names['last_name'].sample(random: Gimei.config.rng) #: [String, String, String]
+      @name = NameWord.new(name)
     end
   end
 

sig/gimei.rbs

@@ -3,7 +3,7 @@ class Gimei
 
   GENDERS: [:male, :female]
   extend Forwardable
-  self.@names: untyped # (Hash['first_name', Hash[('male' | 'female'), [String, String, String]]] | Hash['last_name', [String, String, String]])
+  self.@names: untyped # (Hash['first_name', Hash[('male' | 'female'), Array[[String, String, String]]]] | Hash['last_name', Array[[String, String, String]]])
   self.@addresses: Hash['addresses', Hash[('prefecture' | 'city' | 'town'), [String, String, String]]]
   self.@unique: UniqueGenerator
   self.@config: Config
@@ -13,8 +13,8 @@ class Gimei
   def self.male: -> Name
   def self.female: -> Name
   def self.name: (?gender_type? gender) -> Name
-  def self.names: -> untyped # (Hash['first_name', Hash[('male' | 'female'), [String, String, String]]] | Hash['last_name', [String, String, String]])
-  def self.addresses: -> Hash['addresses', Hash[('prefecture' | 'city' | 'town'), [String, String, String]]]
+  def self.names: -> untyped # (Hash['first_name', Hash[('male' | 'female'), Array[[String, String, String]]]] | Hash['last_name', Array[[String, String, String]]])
+  def self.addresses: -> Hash['addresses', Hash[('prefecture' | 'city' | 'town'), Array[[String, String, String]]]]
   def self.kanji: -> String
   def self.hiragana: -> String
   def self.katakana: -> String

sig/gimei/romaji.rbs

@@ -0,0 +1,4 @@
+module Romaji
+  def self.romaji2kana: (String, Hash[Symbol, Symbol]?) -> String
+  def self.kana2romaji: (String) -> String
+end

steep_expectations.yml

@@ -0,0 +1,23 @@
+---
+- file: lib/gimei.rb
+  diagnostics:
+  - range:
+      start:
+        line: 27
+        character: 4
+      end:
+        line: 27
+        character: 18
+    severity: ERROR
+    message: Type `singleton(::Class)` does not have method `def_delegators`
+    code: Ruby::NoMethod
+  - range:
+      start:
+        line: 28
+        character: 4
+      end:
+        line: 28
+        character: 18
+    severity: ERROR
+    message: Type `singleton(::Class)` does not have method `def_delegators`
+    code: Ruby::NoMethod