Add ability for app to run without application.yml file

config/initializers/figaro.rb

@@ -1,4 +1,4 @@
-require File.expand_path('../../../lib/figaro_yaml_validator', __FILE__)
+require File.join(Rails.root, 'lib', 'config_validator')
 
 Figaro.require_keys(
   'allow_third_party_auth',
@@ -38,4 +38,4 @@
   'valid_service_providers'
 )
 
-FigaroYamlValidator.new.validate
+ConfigValidator.new.validate

lib/config_validator.rb

@@ -0,0 +1,24 @@
+class ConfigValidator
+  def validate(env = ENV)
+    bad_keys = keys_with_bad_values(env, candidate_keys(env))
+    return unless bad_keys.any?
+    raise warning(bad_keys).tr("\\\n", ' ')
+  end
+
+  private
+
+  def candidate_keys(env)
+    env.keys.delete_if { |key| key.starts_with?(Figaro::Application::FIGARO_ENV_PREFIX) }
+  end
+
+  def keys_with_bad_values(env, keys)
+    keys.keep_if { |key| %w(yes no).include?(env[key]) }
+  end
+
+  def warning(bad_keys)
+    <<~HEREDOC
+      You have invalid values for #{bad_keys.uniq.to_sentence} in
+      config/application.yml. Please change them to true or false
+    HEREDOC
+  end
+end

spec/lib/config_validator_spec.rb

@@ -0,0 +1,24 @@
+require 'rails_helper'
+
+describe ConfigValidator do
+  describe '#validator' do
+    it 'raises if one or more candidate key values is set to yes or no' do
+      bad_key = 'bad_key'
+      other_bad_key = 'other_bad_key'
+      noncandidate_key = '_FIGARO_KEY'
+      good_key = 'good_key'
+
+      env = {
+        bad_key => 'yes',
+        other_bad_key => 'no',
+        noncandidate_key => 'yes',
+        good_key => 'foo'
+      }
+
+      expect { ConfigValidator.new.validate(env) }.to raise_error(
+        RuntimeError,
+        /You have invalid values for #{bad_key} and #{other_bad_key}/
+      )
+    end
+  end
+end