Refactor in order to add support for class variables

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## Main
 
-Nothing so far
+#### Additions
+* Refactor to support class variables as well
 
 ## 0.1.0
 

README.md

@@ -41,13 +41,6 @@ require 'minitest/substitute'
 
 ## Usage
 
-This lightweight gem implements features on a "as needed" basis, as of now:
-
-* substitution of instance variables
-* substitution of global variables
-
-Please [create an issue describing your use case](https://github.com/svoop/minitest-substitute/issues) in case you need more features such as the substitution of class variables or substitution via accessor methods.
-
 ### Block
 
 To substitute the value of an instance variable for the duration of a block:
@@ -59,11 +52,27 @@ class Config
   end
 end
 
-Config.instance_variable_get('@version')     # => 1
-with '@version', 2, on: Config do
-  Config.instance_variable_get('@version')   # => 2
+config = Config.new
+
+config.instance_variable_get('@version')     # => 1
+with '@version', 2, on: config do
+  config.instance_variable_get('@version')   # => 2
+end
+config.instance_variable_get('@version')     # => 1
+```
+
+Class variables can be substituted as well:
+
+```ruby
+class Config
+  @@counter = 0
+end
+
+Config.class_variable_get('@@counter')     # => 0
+with '@@counter', 42, on: Config do
+  Config.class_variable_get('@@counter')   # => 42
 end
-Config.instance_variable_get('@version')     # => 1
+Config.class_variable_get('@@counter')     # => 0
 ```
 
 Same goes for global variables:

lib/minitest/substitute.rb

@@ -2,6 +2,7 @@
 
 require_relative 'substitute/version'
 
+require_relative 'substitute/substitutor'
 require_relative 'substitute/with'
 require_relative 'substitute/spec'
 

lib/minitest/substitute/spec.rb

@@ -3,9 +3,6 @@
 require 'minitest/spec'
 
 Minitest::Spec::DSL.class_eval do
-  class Substitutor
-    include Minitest::Substitute::With
-  end
 
   # Substitute the variable value for the duration of the current description
   #
@@ -14,12 +11,13 @@ class Substitutor
   # @param on [Object, nil] substitute in the context of this object
   # @yield temporary substitution value (takes precedence over +substitute+ param)
   def with(variable, substitute=nil, on: self)
+    substitute = yield if block_given?
+    substitutor = Minitest::Substitute::Substitutor.new(variable, substitute, on: on)
     before do
-      substitute = yield if block_given?
-      Substitutor.send(:commit_substitution, variable, substitute, on: on)
+      substitutor.commit
     end
     after do
-      Substitutor.send(:rollback_substitution, variable, on: on)
+      substitutor.rollback
     end
   end
 
@@ -44,4 +42,5 @@ def after(_type=nil, &block)
       end
     end)  #.then &:include
   end
+
 end

lib/minitest/substitute/substitutor.rb

@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+module Minitest
+  module Substitute
+    class Substitutor
+
+      EVAL_METHODS = [:instance_eval, :instance_eval, :class_eval].freeze
+
+      def initialize(variable, substitute, on:)
+        @variable, @substitute, @on = variable, substitute, on
+        @original = get
+      end
+
+      def commit
+        set @substitute
+      end
+
+      def rollback
+        set @original
+      end
+
+      private
+
+      def eval_method
+        EVAL_METHODS[@variable.count('@')]
+      end
+
+      def get
+        @on.send(eval_method, @variable.to_s)
+      end
+
+      def set(value)
+        @on.send(eval_method, "#{@variable} = value")
+      end
+
+    end
+  end
+end

lib/minitest/substitute/with.rb

@@ -3,10 +3,6 @@
 module Minitest
   module Substitute
     module With
-      @original = {}
-      class << self
-        attr_accessor :original
-      end
 
       # Substitute the variable value for the duration of the given block
       #
@@ -16,22 +12,13 @@ class << self
       # @yield block during which the substitution is made
       # @return [Object] return value of the yielded block
       def with(variable, substitute, on: self)
-        commit_substitution(variable, substitute, on: on)
+        substitutor = Minitest::Substitute::Substitutor.new(variable, substitute, on: on)
+        substitutor.commit
         yield.tap do
-          rollback_substitution(variable, on: on)
+          substitutor.rollback
         end
       end
 
-      private
-
-      def commit_substitution(variable, substitute, on:)
-        Minitest::Substitute::With.original[variable.hash] = on.instance_eval variable.to_s
-        on.instance_eval "#{variable} = substitute"
-      end
-
-      def rollback_substitution(variable, on:)
-        on.instance_eval "#{variable} = Minitest::Substitute::With.original.delete(variable.hash)"
-      end
     end
   end
 end

spec/factory.rb

@@ -5,6 +5,8 @@ def initialize
     @version = 1
     @released_on = '2023-08-24'
   end
+
+  @@counter = 0
 end
 
 $_spec_config_instance = Config.new

spec/lib/minitest/substitute/spec_spec.rb

@@ -4,7 +4,7 @@
 require_relative '../../../factory'
 
 describe :with do
-  10.times do   # test value reset even though order is random
+  10.times do   # test rollback even though order is random
     describe "instance variable" do
       context 'untouched' do
         it "returns the original value" do
@@ -22,7 +22,25 @@
     end
   end
 
-  10.times do   # test value reset even though order is random
+  10.times do   # test rollback even though order is random
+    describe "class variable" do
+      context 'untouched' do
+        it "returns the original value" do
+          _(Config.class_variable_get(:@@counter)).must_equal 0
+        end
+      end
+
+      context 'substituted' do
+        with '@@counter', 42, on: Config
+
+        it "returns the substitute value" do
+          _(Config.class_variable_get(:@@counter)).must_equal 42
+        end
+      end
+    end
+  end
+
+  10.times do   # test rollback even though order is random
     describe "global variable" do
       context 'untouched' do
         it "returns the original value" do
@@ -40,7 +58,7 @@
     end
   end
 
-  10.times do   # test value reset even though order is random
+  10.times do   # test rollback even though order is random
     describe "environment variable" do
       context 'untouched' do
         it "returns the original value" do
@@ -58,7 +76,7 @@
     end
   end
 
-  10.times do   # test value reset even though order is random
+  10.times do   # test rollback even though order is random
     describe "multiple substitutions" do
       context 'untouched' do
         it "returns the original values" do

spec/lib/minitest/substitute/substitutor_spec.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+require_relative '../../../spec_helper'
+require_relative '../../../factory'
+
+describe :eval_method do
+  subject do
+    Minitest::Substitute::Substitutor
+  end
+
+  it "returns instance_eval for instance variables" do
+    _(subject.new('@version', nil, on: $_spec_config_instance).send(:eval_method)).must_equal :instance_eval
+  end
+
+  it "returns class_eval for class variables" do
+    _(subject.new('@@counter', nil, on: Config).send(:eval_method)).must_equal :class_eval
+  end
+
+  it "returns instance_eval for global variables" do
+    _(subject.new('$foobar', nil, on: Object).send(:eval_method)).must_equal :instance_eval
+  end
+
+  it "returns instance_eval for global accessors" do
+    _(subject.new('ENV', nil, on: Object).send(:eval_method)).must_equal :instance_eval
+  end
+end

spec/lib/minitest/substitute/with_spec.rb

@@ -14,6 +14,16 @@
     end
   end
 
+  describe "class variable" do
+    it "substitutes the value for the duration of a block" do
+      _(Config.class_variable_get(:@@counter)).must_equal 0
+      with '@@counter', 42, on: Config do
+        _(Config.class_variable_get(:@@counter)).must_equal 42
+      end
+      _(Config.class_variable_get(:@@counter)).must_equal 0
+    end
+  end
+
   describe "global variable" do
     it "substitutes the value for the duration of a block" do
       _($_spec_global_variable).must_equal :original