diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index e44d90e..5d60383 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby-version: ['2.6']
+        ruby-version: ['3.0']
     steps:
     - uses: actions/checkout@v2
     - name: Set up Ruby
@@ -32,7 +32,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby-version: ['2.6', '2.7', '3.0', '3.1']
+        ruby-version: ['3.0', '3.1', '3.2']
 
     steps:
     - uses: actions/checkout@v2
diff --git a/.rubocop.yml b/.rubocop.yml
index a1fb4cc..e39181b 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -6,7 +6,7 @@ require:
   - rubocop-rake
 
 AllCops:
-  TargetRubyVersion: 2.6
+  TargetRubyVersion: 3.0
   NewCops: enable
   DefaultFormatter: progress
   DisplayCopNames: true
diff --git a/Gemfile b/Gemfile
index 81c0ea8..583e6e1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,8 +7,8 @@ gemspec
 
 gem "debug", ">= 1.0.0", require: false
 gem "minitest", "~> 5.0"
-gem "rake", "~> 13.0", ">= 13.0.6"
-gem "rubocop", "~> 1.23"
-gem "rubocop-minitest", "~> 0.17.0"
-gem "rubocop-performance", "~> 1.12"
+gem "rake", "~> 13.0.0", ">= 13.0.6"
+gem "rubocop", "~> 1.48.0"
+gem "rubocop-minitest", "~> 0.29.0"
+gem "rubocop-performance", "~> 1.16.0"
 gem "rubocop-rake", "~> 0.6.0"
diff --git a/Gemfile.lock b/Gemfile.lock
index c2202c2..e26a7ea 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    annealing (0.3.0)
+    annealing (0.4.0)
 
 GEM
   remote: https://rubygems.org/
@@ -10,40 +10,42 @@ GEM
     debug (1.4.0)
       irb (>= 1.3.6)
       reline (>= 0.2.7)
-    io-console (0.5.11)
-    irb (1.4.1)
+    io-console (0.6.0)
+    irb (1.6.3)
       reline (>= 0.3.0)
-    minitest (5.14.4)
-    parallel (1.21.0)
-    parser (3.0.3.2)
+    json (2.6.3)
+    minitest (5.18.0)
+    parallel (1.22.1)
+    parser (3.2.1.1)
       ast (~> 2.4.1)
-    rainbow (3.0.0)
+    rainbow (3.1.1)
     rake (13.0.6)
-    regexp_parser (2.2.0)
-    reline (0.3.1)
+    regexp_parser (2.7.0)
+    reline (0.3.2)
       io-console (~> 0.5)
     rexml (3.2.5)
-    rubocop (1.23.0)
+    rubocop (1.48.0)
+      json (~> 2.3)
       parallel (~> 1.10)
-      parser (>= 3.0.0.0)
+      parser (>= 3.2.0.0)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 1.8, < 3.0)
-      rexml
-      rubocop-ast (>= 1.12.0, < 2.0)
+      rexml (>= 3.2.5, < 4.0)
+      rubocop-ast (>= 1.26.0, < 2.0)
       ruby-progressbar (~> 1.7)
-      unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.14.0)
-      parser (>= 3.0.1.1)
-    rubocop-minitest (0.17.0)
-      rubocop (>= 0.90, < 2.0)
-    rubocop-performance (1.12.0)
+      unicode-display_width (>= 2.4.0, < 3.0)
+    rubocop-ast (1.27.0)
+      parser (>= 3.2.1.0)
+    rubocop-minitest (0.29.0)
+      rubocop (>= 1.39, < 2.0)
+    rubocop-performance (1.16.0)
       rubocop (>= 1.7.0, < 2.0)
       rubocop-ast (>= 0.4.0)
     rubocop-rake (0.6.0)
       rubocop (~> 1.0)
-    ruby-prof (1.4.3)
-    ruby-progressbar (1.11.0)
-    unicode-display_width (2.1.0)
+    ruby-prof (1.6.1)
+    ruby-progressbar (1.13.0)
+    unicode-display_width (2.4.2)
 
 PLATFORMS
   ruby
@@ -52,12 +54,12 @@ DEPENDENCIES
   annealing!
   debug (>= 1.0.0)
   minitest (~> 5.0)
-  rake (~> 13.0, >= 13.0.6)
-  rubocop (~> 1.23)
-  rubocop-minitest (~> 0.17.0)
-  rubocop-performance (~> 1.12)
+  rake (~> 13.0.0, >= 13.0.6)
+  rubocop (~> 1.48.0)
+  rubocop-minitest (~> 0.29.0)
+  rubocop-performance (~> 1.16.0)
   rubocop-rake (~> 0.6.0)
-  ruby-prof (~> 1.4, >= 1.4.3)
+  ruby-prof (~> 1.6, >= 1.6.1)
 
 BUNDLED WITH
-   2.1.4
+   2.4.4
diff --git a/annealing.gemspec b/annealing.gemspec
index 55929c9..ad61307 100644
--- a/annealing.gemspec
+++ b/annealing.gemspec
@@ -12,7 +12,7 @@ Gem::Specification.new do |spec|
   spec.summary       = "Simulated Annealing"
   spec.description   = "Simulated Annealing algoritm implementation."
   spec.homepage      = "https://github.com/3zcurdia/annealing"
-  spec.required_ruby_version = Gem::Requirement.new(">= 2.6.0")
+  spec.required_ruby_version = Gem::Requirement.new(">= 3.0.0")
 
   # spec.metadata["allowed_push_host"] = "TODO: Set to 'http://mygemserver.com'"
 
@@ -29,6 +29,6 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_development_dependency "ruby-prof", "~> 1.4", ">= 1.4.3"
+  spec.add_development_dependency "ruby-prof", "~> 1.6", ">= 1.6.1"
   spec.metadata["rubygems_mfa_required"] = "true"
 end
diff --git a/bin/run b/bin/run
index 268e652..0a0b941 100755
--- a/bin/run
+++ b/bin/run
@@ -45,13 +45,13 @@ solution = simulator.run(locations,
                          state_change: state_change)
 
 puts "\nInitial itinerary:"
-locations.each_cons(2).each_with_index do |(location1, location2), index|
+locations.each_cons(2).with_index do |(location1, location2), index|
   puts "Stop ##{index + 1}: #{location1.name} -> #{location2.name} (#{location1.distance(location2)})"
 end
 puts "-------\nEnergy: #{energy_calculator.call(locations)}"
 
 puts "\nAnnealed itinerary:"
-solution.state.each_cons(2).each_with_index do |(location1, location2), index|
+solution.state.each_cons(2).with_index do |(location1, location2), index|
   puts "Stop ##{index + 1}: #{location1.name} -> #{location2.name} (#{location1.distance(location2)})"
 end
 puts "-------\nEnergy: #{solution.energy}"
diff --git a/lib/annealing/version.rb b/lib/annealing/version.rb
index e2e00aa..d37757b 100644
--- a/lib/annealing/version.rb
+++ b/lib/annealing/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Annealing
-  VERSION = "0.3.0"
+  VERSION = "0.4.0"
 end
diff --git a/test/annealing/configuration/coolers_test.rb b/test/annealing/configuration/coolers_test.rb
index b751f1b..3c3ef9b 100644
--- a/test/annealing/configuration/coolers_test.rb
+++ b/test/annealing/configuration/coolers_test.rb
@@ -15,6 +15,7 @@ def setup
       def test_linear_cooler_reduces_temperature_linearly
         cooler = @coolers.linear
         cooled_temp = cooler.call(nil, @temperature, @cooling_rate, @step)
+
         assert_in_delta @temperature - @cooling_rate,
                         cooled_temp
       end
@@ -22,6 +23,7 @@ def test_linear_cooler_reduces_temperature_linearly
       def test_exponential_cooler_reduces_temperature_exponentially
         cooler = @coolers.exponential
         cooled_temp = cooler.call(nil, @temperature, @cooling_rate, @step)
+
         assert_in_delta @temperature - (Math.exp(@step - 1) * @cooling_rate),
                         cooled_temp
       end
@@ -30,6 +32,7 @@ def test_geometric_cooler_reduces_temperature_geometrically
         ratio = 3
         cooler = @coolers.geometric(ratio)
         cooled_temp = cooler.call(nil, @temperature, @cooling_rate, @step)
+
         assert_in_delta @temperature - (@cooling_rate * (ratio**(@step - 1))),
                         cooled_temp
       end
diff --git a/test/annealing/configuration/terminators_test.rb b/test/annealing/configuration/terminators_test.rb
index dee8fb3..e173708 100644
--- a/test/annealing/configuration/terminators_test.rb
+++ b/test/annealing/configuration/terminators_test.rb
@@ -11,6 +11,7 @@ def setup
 
       def test_zero_temperature_terminator_true_when_temperature_is_zero
         terminator = @terminators.temp_is_zero?
+
         assert terminator.call(nil, nil, 0)
         assert terminator.call(nil, nil, -1)
         refute terminator.call(nil, nil, 1)
@@ -18,6 +19,7 @@ def test_zero_temperature_terminator_true_when_temperature_is_zero
 
       def test_zero_energy_terminator_true_when_energy_or_temperature_is_zero
         terminator = @terminators.energy_or_temp_is_zero?
+
         assert terminator.call(nil, 0, 0)
         assert terminator.call(nil, 0, 1)
         assert terminator.call(nil, 1, 0)
diff --git a/test/annealing/configuration_test.rb b/test/annealing/configuration_test.rb
index 457d6bb..bf11101 100644
--- a/test/annealing/configuration_test.rb
+++ b/test/annealing/configuration_test.rb
@@ -15,6 +15,7 @@ def setup
 
     def test_sets_a_default_linear_cool_down_function
       cool_down = @subject.new.cool_down
+
       assert_respond_to cool_down, :call
       assert_equal 1, cool_down.call(nil, 2, 1, nil)
     end
@@ -31,6 +32,7 @@ def test_sets_a_default_initial_temperature
 
     def test_sets_a_default_termination_condition_function
       termination_condition = @subject.new.termination_condition
+
       assert_respond_to termination_condition, :call
       refute termination_condition.call(nil, nil, 1)
       assert termination_condition.call(nil, nil, 0)
@@ -47,12 +49,14 @@ def test_does_not_set_a_default_state_change_function
 
     def test_forces_cooling_rate_to_float
       configuration = @subject.new(cooling_rate: 99)
+
       assert_kind_of Float, configuration.cooling_rate
       assert_in_delta 99.0, configuration.cooling_rate
     end
 
     def test_forces_temperature_to_float
       configuration = @subject.new(temperature: 999)
+
       assert_kind_of Float, configuration.temperature
       assert_in_delta 999.0, configuration.temperature
     end
@@ -60,6 +64,7 @@ def test_forces_temperature_to_float
     def test_merge_creates_new_configuration_from_config_hash
       new_temperature = 3000
       new_config = @valid_configuration.merge(temperature: new_temperature)
+
       refute_equal @valid_configuration.object_id, new_config.object_id
       assert_equal new_config.temperature, new_temperature
       refute_equal @valid_configuration.temperature, new_config.temperature
@@ -67,6 +72,7 @@ def test_merge_creates_new_configuration_from_config_hash
 
     def test_merge_inherits_current_configuration_attributes
       new_config = @valid_configuration.merge({})
+
       assert_equal @valid_configuration.cool_down,
                    new_config.cool_down
       assert_equal @valid_configuration.cooling_rate,
@@ -85,6 +91,7 @@ def test_merge_changing_new_configuration_does_not_affect_original
       new_config = @valid_configuration.merge({})
       new_config.cooling_rate += 0.005
       new_config.temperature -= 100
+
       refute_equal @valid_configuration.cooling_rate,
                    new_config.cooling_rate
       refute_equal @valid_configuration.temperature,
@@ -93,48 +100,48 @@ def test_merge_changing_new_configuration_does_not_affect_original
 
     def test_validates_temperature_is_not_negative
       @valid_configuration.validate!
+      @valid_configuration.temperature = -100
       assert_raises(@error_class, "Initial temperature cannot be negative") do
-        @valid_configuration.temperature = -100
         @valid_configuration.validate!
       end
     end
 
     def test_validates_cooling_rate_is_not_negative
       @valid_configuration.validate!
+      @valid_configuration.cooling_rate = -0.005
       assert_raises(@error_class, "Cooling rate cannot be negative") do
-        @valid_configuration.cooling_rate = -0.005
         @valid_configuration.validate!
       end
     end
 
     def test_validates_cool_down_funtion_is_callable
       @valid_configuration.validate!
+      @valid_configuration.cool_down = nil
       assert_raises(@error_class, "Missing cool down function") do
-        @valid_configuration.cool_down = nil
         @valid_configuration.validate!
       end
     end
 
     def test_validates_energy_calculator_is_callable
       @valid_configuration.validate!
+      @valid_configuration.termination_condition = nil
       assert_raises(@error_class, "Missing energy calculator function") do
-        @valid_configuration.termination_condition = nil
         @valid_configuration.validate!
       end
     end
 
     def test_validates_state_change_is_callable
       @valid_configuration.validate!
+      @valid_configuration.energy_calculator = nil
       assert_raises(@error_class, "Missing state change function") do
-        @valid_configuration.energy_calculator = nil
         @valid_configuration.validate!
       end
     end
 
     def test_validates_termination_condition_is_callable
       @valid_configuration.validate!
+      @valid_configuration.state_change = nil
       assert_raises(@error_class, "Missing termination condition function") do
-        @valid_configuration.state_change = nil
         @valid_configuration.validate!
       end
     end
diff --git a/test/annealing/metal_test.rb b/test/annealing/metal_test.rb
index 3afc38a..142c1fc 100644
--- a/test/annealing/metal_test.rb
+++ b/test/annealing/metal_test.rb
@@ -22,6 +22,7 @@ def test_energy_calls_energy_calculator_with_current_state
       custom_calculator.expect(:call, 42, [@collection])
       local_config = @global_config.merge(energy_calculator: custom_calculator)
       metal = Annealing::Metal.new(@collection, @temperature, local_config)
+
       assert_equal 42, metal.energy
     end
 
@@ -29,6 +30,7 @@ def test_cooled_returns_metal_instance_with_new_temperature
       metal = Annealing::Metal.new(@collection, @temperature)
       new_temperature = @temperature - 1
       cooled_metal = metal.cool!(new_temperature)
+
       assert_instance_of Annealing::Metal, cooled_metal
       assert_equal new_temperature, cooled_metal.temperature
     end
@@ -48,6 +50,7 @@ def test_cooled_returns_cooled_metal_when_preferred
       cooled_metal = metal.stub(:prefer?, true) do
         metal.cool!(new_temperature)
       end
+
       refute_same metal, cooled_metal
       refute_equal new_temperature, metal.temperature
     end
@@ -58,6 +61,7 @@ def test_cooled_returns_the_original_metal_when_not_preferred
       cooled_metal = metal.stub(:prefer?, false) do
         metal.cool!(new_temperature)
       end
+
       assert_same metal, cooled_metal
       assert_equal new_temperature, metal.temperature
     end
diff --git a/test/annealing/simulator_test.rb b/test/annealing/simulator_test.rb
index 910a243..bd44abd 100644
--- a/test/annealing/simulator_test.rb
+++ b/test/annealing/simulator_test.rb
@@ -24,6 +24,7 @@ def setup
 
     def test_inherits_global_configuration_by_default
       simulator_config = @simulator.configuration
+
       assert_equal @global_config.cool_down,
                    simulator_config.cool_down
       assert_equal @global_config.cooling_rate,
@@ -45,6 +46,7 @@ def test_can_specify_custom_configuration_values_on_initialization
         state_change: ->(state) { state.shuffle },
         temperature: 99
       ).configuration
+
       refute_equal @global_config.cooling_rate,
                    simulator_config.cooling_rate
       refute_equal @global_config.energy_calculator,
@@ -61,6 +63,7 @@ def test_can_specify_custom_configuration_values_on_run
       }
       state = @simulator.run(@collection,
                              termination_condition: termination_condition)
+
       assert_equal @temperature - 10, state.temperature
     end
 
@@ -86,6 +89,7 @@ def test_runs_simulation_until_termination_condition_is_met
                                                  final_temp])
       state = @simulator.run(@collection,
                              termination_condition: termination_condition)
+
       assert_equal final_temp, state.temperature
       termination_condition.verify
     end
@@ -99,6 +103,7 @@ def test_uses_cool_down_function_to_reduce_temperature_at_each_step
                                            @cooling_rate, step + 1])
       end
       state = @simulator.run(@collection, cool_down: cool_down)
+
       assert_equal 0, state.temperature
       cool_down.verify
     end