Use Minitest module instead of MiniTest compatibility layer

sassc.gemspec

@@ -26,7 +26,7 @@ Gem::Specification.new do |spec|
  spec.platform = Gem::Platform::RUBY
  spec.extensions = ["ext/extconf.rb"]
 
- spec.add_development_dependency "minitest", "~> 5.5.1"
+ spec.add_development_dependency "minitest", ">= 5.5.1", "< 5.20"
  spec.add_development_dependency "minitest-around"
  spec.add_development_dependency "test_construct"
  spec.add_development_dependency "pry"

test/custom_importer_test.rb

@@ -3,7 +3,7 @@
 require_relative "test_helper"
 
 module SassC
- class CustomImporterTest < MiniTest::Test
+ class CustomImporterTest < Minitest::Test
  include TempFileTest
 
  class CustomImporter < Importer

test/engine_test.rb

@@ -3,7 +3,7 @@
 require_relative "test_helper"
 
 module SassC
- class EngineTest < MiniTest::Test
+ class EngineTest < Minitest::Test
  include TempFileTest
 
  def render(data)

test/error_test.rb

@@ -3,7 +3,7 @@
 require_relative "test_helper"
 
 module SassC
- class ErrorTest < MiniTest::Test
+ class ErrorTest < Minitest::Test
  def render(data, opts={})
  Engine.new(data, opts).render
  end

test/functions_test.rb

@@ -4,7 +4,7 @@
 require "stringio"
 
 module SassC
- class FunctionsTest < MiniTest::Test
+ class FunctionsTest < Minitest::Test
  include FixtureHelper
 
  def setup

test/native_test.rb

@@ -9,13 +9,13 @@ module NativeTest
  SAMPLE_CSS_OUTPUT = ".hi {\n width: 30px; }\n"
  BAD_SASS_STRING = "$size = 30px;"
 
- class General < MiniTest::Test
+ class General < Minitest::Test
  def test_it_reports_the_libsass_version
  assert_equal "3.6.4", Native.version
  end
  end
 
- class DataContext < MiniTest::Test
+ class DataContext < Minitest::Test
  def teardown
  Native.delete_data_context(@data_context) if @data_context
  end
@@ -105,7 +105,7 @@ def test_custom_function
  end
  end
 
- class FileContext < MiniTest::Test
+ class FileContext < Minitest::Test
  include TempFileTest
 
  def teardown

test/output_style_test.rb

@@ -3,7 +3,7 @@
 require_relative "test_helper"
 
 module SassC
- class OutputStyleTest < MiniTest::Test
+ class OutputStyleTest < Minitest::Test
  def input_scss
  input_scss = <<-CSS
 $color: #fff;

test/sass_2_scss_test.rb

@@ -3,7 +3,7 @@
 require_relative "test_helper"
 
 module SassC
- class Sass2ScssTest < MiniTest::Test
+ class Sass2ScssTest < Minitest::Test
  def test_compact_output
  assert_equal ".blat { color: red; }", Sass2Scss.convert(<<SASS)
 .blat