Camelize strategy name in shared examples

Following up on #681, we also need to camelize strategy names
in the RSpec shared examples for cleaning strategies.

For developer convenience, the methods for string manipulation
were moved from the Cleaner class to a dedicated StringHelper module.

Author: Leo Arnold

lib/database_cleaner/cleaner.rb

@@ -1,21 +1,24 @@
 require 'database_cleaner/null_strategy'
 require 'database_cleaner/strategy'
+require 'database_cleaner/string_helper'
 require 'forwardable'
 
 module DatabaseCleaner
   class UnknownStrategySpecified < ArgumentError; end
 
   class Cleaner
     def self.available_strategies(orm_module)
-      # introspect publically available constants for descendents of Strategy to get list of strategies
-      # ignore classes named Base, because its a common name for a shared base class that adds ORM access stuff to Strategy before being inherited by final concrete class
+      # introspect publicly available constants for descendents of Strategy to get list of strategies
+      # ignore classes named Base, because it's a common name for a shared base class that adds ORM access stuff to Strategy before being inherited by final concrete class
       # if you're writing an adapter and this method is falsely returning an internal constant that isn't a valid strategy, consider making it private with Module#private_constant.
-      orm_module.constants.select do |constant_name|
+      orm_module.constants.filter_map do |constant_name|
+        next if constant_name == :Base
+
         ancestors = orm_module.const_get(constant_name).ancestors rescue []
-        ancestors.include?(DatabaseCleaner::Strategy)
-      end.map do |constant_name|
-        underscore(constant_name).to_sym
-      end - [:base]
+        next unless ancestors.include?(DatabaseCleaner::Strategy)
+
+        StringHelper.underscore(constant_name).to_sym
+      end
     end
 
     include Comparable
@@ -86,37 +89,16 @@ def create_strategy(*args)
     end
 
     def orm_strategy(strategy)
-      strategy_module_name = camelize(strategy)
+      strategy_module_name = StringHelper.camelize(strategy)
       orm_module.const_get(strategy_module_name)
     rescue NameError
       available_strategies = self.class.available_strategies(orm_module)
       raise UnknownStrategySpecified, "The '#{strategy}' strategy does not exist for the #{orm} ORM!  Available strategies: #{available_strategies.join(', ')}"
     end
 
     def orm_module
-      orm_module_name = camelize(orm)
+      orm_module_name = StringHelper.camelize(orm)
       DatabaseCleaner.const_get(orm_module_name)
     end
-
-    # copied from ActiveSupport to avoid adding it as a dependency
-
-    def camelize(term)
-      string = term.to_s
-      string = string.sub(/^[a-z\d]*/) { |match| match.capitalize }
-      string.gsub!(/(?:_|(\/))([a-z\d]*)/i) { "#{$1}#{$2.capitalize}" }
-      string.gsub!("/", "::")
-      string
-    end
-
-    def self.underscore(camel_cased_word)
-      return camel_cased_word unless /[A-Z-]|::/.match?(camel_cased_word)
-      word = camel_cased_word.to_s.gsub("::", "/")
-      word.gsub!(/([A-Z\d]+)([A-Z][a-z])/, '\1_\2')
-      word.gsub!(/([a-z\d])([A-Z])/, '\1_\2')
-      word.tr!("-", "_")
-      word.downcase!
-      word
-    end
-    private_class_method :underscore
   end
 end

lib/database_cleaner/spec/shared_examples.rb

@@ -11,7 +11,7 @@
 RSpec.shared_examples_for "a database_cleaner adapter" do
   describe 'all strategies should adhere to a database_cleaner strategy interface' do
     DatabaseCleaner::Cleaner.available_strategies(described_class).each do |strategy|
-      subject { described_class.const_get(strategy.to_s.capitalize).new }
+      subject { described_class.const_get(DatabaseCleaner::StringHelper.camelize(strategy.to_s)).new }
 
       it_behaves_like 'a database_cleaner strategy'
     end

lib/database_cleaner/string_helper.rb

@@ -0,0 +1,22 @@
+module DatabaseCleaner
+  # Methods copied from ActiveSupport to avoid adding it as a dependency
+  module StringHelper
+    def self.camelize(term)
+      string = term.to_s
+      string = string.sub(/^[a-z\d]*/) { |match| match.capitalize }
+      string.gsub!(/(?:_|(\/))([a-z\d]*)/i) { "#{$1}#{$2.capitalize}" }
+      string.gsub!("/", "::")
+      string
+    end
+
+    def self.underscore(camel_cased_word)
+      return camel_cased_word unless /[A-Z-]|::/.match?(camel_cased_word)
+      word = camel_cased_word.to_s.gsub("::", "/")
+      word.gsub!(/([A-Z\d]+)([A-Z][a-z])/, '\1_\2')
+      word.gsub!(/([a-z\d])([A-Z])/, '\1_\2')
+      word.tr!("-", "_")
+      word.downcase!
+      word
+    end
+  end
+end