diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 000000000..532d726e6
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,21 @@
+---
+name: Tests
+on: [ push, pull_request ]
+jobs:
+  test:
+    name: Test (Ruby ${{ matrix.ruby }}, Rails ${{ matrix.rails }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby: [ '2.7', '3.0' ]
+        rails: [ '5.2', '6.0', '6.1' ]
+    env:
+      BUNDLE_GEMFILE: gemfiles/rails-${{ matrix.rails }}.gemfile
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - run: bundle exec rake
\ No newline at end of file
diff --git a/active_shipping.gemspec b/active_shipping.gemspec
index d07eed7da..9ead2444a 100644
--- a/active_shipping.gemspec
+++ b/active_shipping.gemspec
@@ -21,11 +21,11 @@ Gem::Specification.new do |s|
 
 
   s.add_dependency("measured", ">= 2.0")
-  s.add_dependency("activesupport", ">= 4.2", "< 6.1")
+  s.add_dependency("activesupport", ">= 5.2", "< 6.2")
   s.add_dependency("active_utils", "~> 3.3.1")
   s.add_dependency("nokogiri", ">= 1.6")
 
-  s.add_development_dependency("minitest")
+  s.add_development_dependency("minitest", "~> 5.18.0")
   s.add_development_dependency("minitest-reporters")
   s.add_development_dependency("rake")
   s.add_development_dependency("mocha", "~> 1")
diff --git a/gemfiles/activesupport42.gemfile b/gemfiles/activesupport42.gemfile
deleted file mode 100644
index 67f93e540..000000000
--- a/gemfiles/activesupport42.gemfile
+++ /dev/null
@@ -1,5 +0,0 @@
-source "https://rubygems.org"
-
-gemspec path: '..'
-
-gem 'activesupport', '~> 4.2.0'
diff --git a/gemfiles/activesupport50.gemfile b/gemfiles/activesupport50.gemfile
deleted file mode 100644
index 50391f95c..000000000
--- a/gemfiles/activesupport50.gemfile
+++ /dev/null
@@ -1,6 +0,0 @@
-source "https://rubygems.org"
-
-gemspec path: '..'
-
-gem 'activesupport', '~> 5.0.0'
-gem 'active_utils', '~> 3.3.0'
diff --git a/gemfiles/activesupport51.gemfile b/gemfiles/activesupport51.gemfile
deleted file mode 100644
index feffe1399..000000000
--- a/gemfiles/activesupport51.gemfile
+++ /dev/null
@@ -1,5 +0,0 @@
-source "https://rubygems.org"
-
-gemspec path: '..'
-
-gem 'activesupport', '~> 5.1.0'
\ No newline at end of file
diff --git a/gemfiles/activesupport52.gemfile b/gemfiles/activesupport52.gemfile
deleted file mode 100644
index 95534b373..000000000
--- a/gemfiles/activesupport52.gemfile
+++ /dev/null
@@ -1,5 +0,0 @@
-source "https://rubygems.org"
-
-gemspec path: '..'
-
-gem 'activesupport', '~> 5.2.0'
\ No newline at end of file
diff --git a/gemfiles/activesupport_master.gemfile b/gemfiles/activesupport_master.gemfile
deleted file mode 100644
index 94fcb951b..000000000
--- a/gemfiles/activesupport_master.gemfile
+++ /dev/null
@@ -1,5 +0,0 @@
-source "https://rubygems.org"
-
-gemspec path: '..'
-
-gem 'activesupport', github: 'rails/rails'
diff --git a/gemfiles/rails-5.2.gemfile b/gemfiles/rails-5.2.gemfile
new file mode 100644
index 000000000..6d85f7ffb
--- /dev/null
+++ b/gemfiles/rails-5.2.gemfile
@@ -0,0 +1,6 @@
+source "https://rubygems.org"
+
+gem 'activesupport', '~> 5.2.0'
+gem 'i18n'
+
+gemspec path: '..'
\ No newline at end of file
diff --git a/gemfiles/rails-6.0.gemfile b/gemfiles/rails-6.0.gemfile
new file mode 100644
index 000000000..2c12cdcef
--- /dev/null
+++ b/gemfiles/rails-6.0.gemfile
@@ -0,0 +1,6 @@
+source "https://rubygems.org"
+
+gem 'activesupport', '~> 6.0.0'
+gem 'i18n'
+
+gemspec path: '..'
\ No newline at end of file
diff --git a/gemfiles/rails-6.1.gemfile b/gemfiles/rails-6.1.gemfile
new file mode 100644
index 000000000..ad0cff774
--- /dev/null
+++ b/gemfiles/rails-6.1.gemfile
@@ -0,0 +1,6 @@
+source "https://rubygems.org"
+
+gem 'activesupport', '~> 6.1.0'
+gem 'i18n'
+
+gemspec path: '..'
\ No newline at end of file
diff --git a/test/unit/carriers/usps_test.rb b/test/unit/carriers/usps_test.rb
index 6855aa8cf..437cb0bf1 100644
--- a/test/unit/carriers/usps_test.rb
+++ b/test/unit/carriers/usps_test.rb
@@ -384,7 +384,7 @@ def test_package_valid_for_max_dimensions
   end
 
   def test_strip_9_digit_zip_codes
-    request = URI.decode(@carrier.send(:build_us_rate_request, package_fixtures[:book], "90210-1234", "123456789"))
+    request = CGI.unescape(@carrier.send(:build_us_rate_request, package_fixtures[:book], "90210-1234", "123456789"))
     assert !(request =~ /\>90210-1234\</)
     assert request =~ /\>90210\</
     assert !(request =~ /\>123456789\</)
@@ -392,7 +392,7 @@ def test_strip_9_digit_zip_codes
   end
 
   def test_strip_9_digit_zip_codes_world_rates
-    request = URI.decode(@carrier.send(:build_world_rate_request, location_fixtures[:beverly_hills_9_zip],
+    request = CGI.unescape(@carrier.send(:build_world_rate_request, location_fixtures[:beverly_hills_9_zip],
                                         package_fixtures[:book], location_fixtures[:auckland], {}))
     refute_match /\<OriginZip\>90210-1234/, request
     assert_match /\<OriginZip\>90210/, request