Set up static type checking

.github/workflows/test.yml

@@ -29,6 +29,8 @@ jobs:
           bundler-cache: true
       - name: Lint code
         run: bundle exec rubocop
+      - name: Check types
+        run: bundle exec steep check
   specs:
     strategy:
       fail-fast: false

Gemfile

@@ -10,6 +10,11 @@ group :development, :test do
   gem "rubocop-rake", "~> 0.6.0", require: false
 end
 
+group :development do
+  gem "rbs", "~> 3.5", require: false
+  gem "steep", "~> 1.7", require: false
+end
+
 group :test do
   gem "rspec", "~> 3.0"
   gem "rubocop-rspec", "~> 2.29", require: false

Steepfile

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+target :lib do
+  signature "sig"
+
+  check "lib"
+
+  library "yaml"
+  library "set"
+
+  configure_code_diagnostics(Steep::Diagnostic::Ruby.strict)
+end

lib/envy.rb

@@ -36,7 +36,7 @@ def from_file!(*files, perm: nil)
   private
 
   def load_yaml(path, force:)
-    File.open(path) { |file| set_envs YAML.safe_load(file), force: force }
+    File.open(path) { |file| set_envs YAML.safe_load(file.read), force: force }
     nil
   end
 

sig/envy.rbs

@@ -1,4 +1,17 @@
 module Envy
-  VERSION: String
-  # See the writing guide of rbs: https://github.com/ruby/rbs#guides
+  extend ::Envy
+
+  def from_file: (*String files, ?perm: Integer?) -> nil
+
+  def from_file!: (*String files, ?perm: Integer?) -> nil
+
+  private
+
+  def load_yaml: (String path, force: bool) -> nil
+
+  def set_perms: (Array[String] files, ?perm: Integer?) -> void
+
+  def set_envs: (untyped yaml, ?String prev_key, force: bool) -> void
+
+  def load_wrap: () { () -> untyped } -> nil
 end

sig/envy/error.rbs

@@ -0,0 +1,4 @@
+module Envy
+  class Error < ::StandardError
+  end
+end

sig/envy/version.rbs

@@ -0,0 +1,3 @@
+module Envy
+  VERSION: String
+end