diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index c4c202d..9d48e6b 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -13,7 +13,7 @@ jobs:
 
     strategy:
       matrix:
-        ruby-version: [jruby-9.3]
+        ruby-version: [jruby-9.3, jruby-9.4]
 
     steps:
       - uses: actions/checkout@v2
@@ -24,7 +24,7 @@ jobs:
           bundler-cache: true
       - name: Install dependencies
         run: bundle install
-      - name: Run RuboCop
-        run: bundle exec rubocop
       - name: Run test
-        run: bundle exec rake specs
+        run: jruby -Ilib -rbundler/setup -S rake specs
+      - name: Run RuboCop
+        run: jruby -Ilib -rbundler/setup -S rubocop lib
diff --git a/Gemfile b/Gemfile
index 7f4f5e9..e5449c6 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,3 +3,12 @@
 source 'https://rubygems.org'
 
 gemspec
+
+group :development do 
+  gem 'rake', require: false
+  gem 'ruby-debug', '~> 0.11', require: false
+
+  gem 'rubocop', '~> 1.50.2', require: false
+  gem 'rubocop-performance', require: false
+  gem 'rubocop-rake', require: false
+end
diff --git a/Gemfile.lock b/Gemfile.lock
deleted file mode 100644
index 94430c6..0000000
--- a/Gemfile.lock
+++ /dev/null
@@ -1,63 +0,0 @@
-PATH
-  remote: .
-  specs:
-    jar-dependencies (0.4.1)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    ast (2.4.2)
-    columnize (0.9.0)
-    json (2.6.2-java)
-    linecache (1.3.1-java)
-    minitest (5.10.3)
-    parallel (1.22.1)
-    parser (3.1.2.0)
-      ast (~> 2.4.1)
-    rainbow (3.1.1)
-    rake (13.0.6)
-    regexp_parser (2.5.0)
-    rexml (3.2.5)
-    rubocop (1.31.1)
-      json (~> 2.3)
-      parallel (~> 1.10)
-      parser (>= 3.1.0.0)
-      rainbow (>= 2.2.2, < 4.0)
-      regexp_parser (>= 1.8, < 3.0)
-      rexml (>= 3.2.5, < 4.0)
-      rubocop-ast (>= 1.18.0, < 2.0)
-      ruby-progressbar (~> 1.7)
-      unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.18.0)
-      parser (>= 3.1.1.0)
-    rubocop-performance (1.14.2)
-      rubocop (>= 1.7.0, < 2.0)
-      rubocop-ast (>= 0.4.0)
-    rubocop-rake (0.6.0)
-      rubocop (~> 1.0)
-    ruby-debug (0.11.0)
-      columnize (>= 0.1)
-      linecache (~> 1.3.1)
-      ruby-debug-base (~> 0.11.0.0)
-    ruby-debug-base (0.11.0-java)
-    ruby-maven (3.3.13)
-      ruby-maven-libs (~> 3.3.9)
-    ruby-maven-libs (3.3.9)
-    ruby-progressbar (1.11.0)
-    unicode-display_width (2.2.0)
-
-PLATFORMS
-  universal-java-11
-
-DEPENDENCIES
-  jar-dependencies!
-  minitest (~> 5.10.0)
-  rake (~> 13.0)
-  rubocop (~> 1.31)
-  rubocop-performance (~> 1.14)
-  rubocop-rake (~> 0.6)
-  ruby-debug (~> 0.11)
-  ruby-maven (~> 3.3)
-
-BUNDLED WITH
-   2.3.16
diff --git a/jar-dependencies.gemspec b/jar-dependencies.gemspec
index 4f506ef..094aa4b 100644
--- a/jar-dependencies.gemspec
+++ b/jar-dependencies.gemspec
@@ -29,12 +29,7 @@ Gem::Specification.new do |s|
 
   s.required_ruby_version = '>= 2.6'
 
-  s.add_development_dependency 'minitest', '~> 5.10.0'
-  s.add_development_dependency 'rake', '~> 13.0'
-  s.add_development_dependency 'rubocop', '~> 1.31'
-  s.add_development_dependency 'rubocop-performance', '~> 1.14'
-  s.add_development_dependency 'rubocop-rake', '~> 0.6'
-  s.add_development_dependency 'ruby-debug', '~> 0.11'
+  s.add_development_dependency 'minitest', '~> 5.10'
   s.add_development_dependency 'ruby-maven', ruby_maven_version = '~> 3.3'
 
   s.post_install_message = <<~TEXT
diff --git a/lib/jar_dependencies.rb b/lib/jar_dependencies.rb
index 9e24e34..39bb7a0 100644
--- a/lib/jar_dependencies.rb
+++ b/lib/jar_dependencies.rb
@@ -91,7 +91,6 @@ def skip?
     end
 
     def require?
-      @require = nil unless instance_variable_defined?(:@require)
       if @require.nil?
         if (require = to_boolean(REQUIRE)).nil?
           no_require = to_boolean(NO_REQUIRE)
@@ -105,7 +104,12 @@ def require?
     attr_writer :require
 
     def quiet?
-      (@silent ||= false) || to_boolean(QUIET)
+      @quiet = to_boolean(QUIET) if @quiet.nil?
+      @quiet
+    end
+
+    def no_more_warnings
+      @quiet = true
     end
 
     def jarfile
@@ -124,10 +128,6 @@ def vendor?
       to_boolean(VENDOR)
     end
 
-    def no_more_warnings
-      @silent = true
-    end
-
     def freeze_loading
       self.require = false
     end
@@ -198,7 +198,7 @@ def local_maven_repo
     end
 
     def home
-      absolute(to_prop(HOME)) || local_maven_repo
+      @home ||= absolute(to_prop(HOME)) || local_maven_repo
     end
 
     def require_jars_lock!(scope = :runtime)
@@ -242,7 +242,7 @@ def setup(options = nil)
       when Symbol
         require_jars_lock!(options)
       when Hash
-        @jars_home = options[:jars_home]
+        @home = options[:jars_home]
         @jars_lock = options[:jars_lock]
         require_jars_lock!(options[:scope] || :runtime)
       else
@@ -341,18 +341,15 @@ def to_jar(group_id, artifact_id, version, classifier = nil)
 
     def do_require(*args)
       jar = to_jar(*args)
-      local = File.join(Dir.pwd, 'jars', jar)
-      vendor = File.join(Dir.pwd, 'vendor', 'jars', jar)
-      file = File.join(home, jar)
-      # use jar from local repository if exists
-      if File.exist?(file)
-        require file
-      # use jar from PWD/jars if exists
-      elsif File.exist?(local)
-        require local
       # use jar from PWD/vendor/jars if exists
-      elsif File.exist?(vendor)
+      if File.exist?(vendor = File.join(Dir.pwd, 'vendor', 'jars', jar))
         require vendor
+      # use jar from PWD/jars if exists
+      elsif File.exist?(local = File.join(Dir.pwd, 'jars', jar))
+        require local
+      # use jar from local repository if exists
+      elsif File.exist?(file = File.join(home, jar))
+        require file
       else
         # otherwise try to find it on the load path
         require jar
diff --git a/lib/jars/attach_jars_pom.rb b/lib/jars/attach_jars_pom.rb
index 37c20d4..d08ba36 100644
--- a/lib/jars/attach_jars_pom.rb
+++ b/lib/jars/attach_jars_pom.rb
@@ -2,13 +2,13 @@
 
 # this file is maven DSL
 
-(0..10_000).each do |i|
+10_000.times do |i|
   coord = ENV_JAVA["jars.#{i}"]
   break unless coord
 
   artifact = Maven::Tools::Artifact.from_coordinate(coord)
   exclusions = []
-  (0..10_000).each do |j|
+  10_000.times do |j|
     exclusion = ENV_JAVA["jars.#{i}.exclusions.#{j}"]
     break unless exclusion
 
diff --git a/lib/jars/gemspec_artifacts.rb b/lib/jars/gemspec_artifacts.rb
index 9def815..7a4a6b3 100644
--- a/lib/jars/gemspec_artifacts.rb
+++ b/lib/jars/gemspec_artifacts.rb
@@ -17,7 +17,7 @@ def new(*args)
         end
       end
 
-    private
+      private
 
       def convert(arg, low = nil, high = nil)
         if arg.include?('~>')
@@ -58,7 +58,7 @@ def snapshot_version(val)
           val
         end
       end
-  end
+    end
   end
 
   class GemspecArtifacts
@@ -83,7 +83,7 @@ def to_s
       def initialize(line)
         super()
         line.gsub(/'"|^\s*\[|\]\s*$/, '').split(/,\s*/).each do |exclusion|
-          self.<< Exclusion.new(exclusion)
+          self << Exclusion.new(exclusion)
         end
         freeze
       end
@@ -97,7 +97,7 @@ class Artifact
       def initialize(options, *args)
         @type, @group_id, @artifact_id, @classifier, @version, @exclusions = *args
         options.each do |k, v|
-          instance_variable_set("@#{k}", v)
+          instance_variable_set(:"@#{k}", v)
         end
       end
 
diff --git a/lib/jars/lock.rb b/lib/jars/lock.rb
index e776f35..960dba7 100644
--- a/lib/jars/lock.rb
+++ b/lib/jars/lock.rb
@@ -26,7 +26,9 @@ def version
     end
 
     def classifier
-      size == 5 ? nil : self[2]
+      return nil if size == 5
+
+      self[2]
     end
 
     def gacv
diff --git a/lib/jars/maven_factory.rb b/lib/jars/maven_factory.rb
index 4a22f08..c78fee9 100644
--- a/lib/jars/maven_factory.rb
+++ b/lib/jars/maven_factory.rb
@@ -110,7 +110,7 @@ def add_gem_to_load_path(name)
 
     def requirement(name)
       jars = Gem.loaded_specs['jar-dependencies']
-      dep = jars.nil? ? nil : jars.dependencies.detect { |d| d.name == name }
+      dep = jars&.dependencies&.detect { |d| d.name == name }
       dep.nil? ? Gem::Requirement.create('>0') : dep.requirement
     end
 
@@ -122,7 +122,7 @@ def install_gem(name, req)
       inst.install(name, req).first
     rescue => e
       if Jars.verbose?
-        warn e.inspect.to_s
+        warn e.inspect
         warn e.backtrace.join("\n")
       end
       raise "there was an error installing '#{name} (#{req})' " \
diff --git a/lib/jars/maven_settings.rb b/lib/jars/maven_settings.rb
index 7fbe1c6..7f1b291 100644
--- a/lib/jars/maven_settings.rb
+++ b/lib/jars/maven_settings.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require 'rubygems/uri_formatter'
 module Jars
   class MavenSettings
     LINE_SEPARATOR = ENV_JAVA['line.separator']
@@ -8,8 +7,14 @@ class MavenSettings
     class << self
       def local_settings
         @_jars_maven_local_settings_ = nil unless instance_variable_defined?(:@_jars_maven_local_settings_)
-        if @_jars_maven_local_settings_.nil? && (settings = Jars.absolute('settings.xml')) && File.exist?(settings)
-          @_jars_maven_local_settings_ = settings
+        if @_jars_maven_local_settings_.nil?
+          settings = Jars.absolute('settings.xml')
+          @_jars_maven_local_settings_ =
+            if settings && File.exist?(settings)
+              settings
+            else
+              false
+            end
         end
         @_jars_maven_local_settings_ || nil
       end
diff --git a/lib/jars/post_install_hook.rb b/lib/jars/post_install_hook.rb
index d755671..d979b71 100644
--- a/lib/jars/post_install_hook.rb
+++ b/lib/jars/post_install_hook.rb
@@ -23,7 +23,7 @@
 
 if defined?(JRUBY_VERSION) && Gem.post_install_hooks.empty?
   Gem.post_install do |gem_installer|
-    unless (ENV['JARS_SKIP'] || ENV_JAVA['jars.skip']) == 'true'
+    if ENV['JARS_SKIP'] != 'true' && ENV_JAVA['jars.skip'] != 'true'
       require 'jars/installer'
       jars = Jars::Installer.new(gem_installer.spec)
       jars.ruby_maven_install_options = gem_installer.options || {}
diff --git a/specs/classpath_spec.rb b/specs/classpath_spec.rb
index 3676f8a..6f8bd29 100644
--- a/specs/classpath_spec.rb
+++ b/specs/classpath_spec.rb
@@ -123,40 +123,40 @@ def self.prepare(array)
   it 'resolves classpath from gemspec' do
     ENV_JAVA['jars.quiet'] = 'true'
     Dir.chdir(File.dirname(example_spec)) do
-      Helper.prepare(subject.classpath).must_equal Helper.prepare(example_expected)
+      _(Helper.prepare(subject.classpath)).must_equal Helper.prepare(example_expected)
 
-      Helper.prepare(subject.classpath(:compile)).must_equal Helper.prepare(
+      _(Helper.prepare(subject.classpath(:compile))).must_equal Helper.prepare(
         expected_with_bc + ['org/slf4j/slf4j-simple/1.7.7/slf4j-simple-1.7.7.jar']
       )
 
-      Helper.prepare(subject.classpath(:test)).must_equal Helper.prepare(expected_with_bc + [
+      _(Helper.prepare(subject.classpath(:test))).must_equal Helper.prepare(expected_with_bc + [
         'junit/junit/4.12/junit-4.12.jar',
         'org/slf4j/slf4j-simple/1.7.7/slf4j-simple-1.7.7.jar',
         'org/hamcrest/hamcrest-core/1.3/hamcrest-core-1.3.jar'
       ])
 
-      Helper.prepare(subject.classpath(:runtime)).must_equal Helper.prepare(example_expected)
+      _(Helper.prepare(subject.classpath(:runtime))).must_equal Helper.prepare(example_expected)
     end
   end
 
   it 'resolves classpath_string from gemspec' do
     ENV_JAVA['jars.quiet'] = 'true'
     Dir.chdir(File.dirname(example_spec)) do
-      Helper.prepare(subject.classpath_string.split(File::PATH_SEPARATOR)).must_equal Helper.prepare(example_expected)
+      _(Helper.prepare(subject.classpath_string.split(File::PATH_SEPARATOR))).must_equal Helper.prepare(example_expected)
 
-      Helper.prepare(subject.classpath_string(:compile).split(File::PATH_SEPARATOR))
+      _(Helper.prepare(subject.classpath_string(:compile).split(File::PATH_SEPARATOR)))
             .must_equal Helper.prepare(
               expected_with_bc + ['org/slf4j/slf4j-simple/1.7.7/slf4j-simple-1.7.7.jar']
             )
 
-      Helper.prepare(subject.classpath_string(:test).split(File::PATH_SEPARATOR))
+      _(Helper.prepare(subject.classpath_string(:test).split(File::PATH_SEPARATOR)))
             .must_equal Helper.prepare(expected_with_bc + [
               'junit/junit/4.12/junit-4.12.jar',
               'org/slf4j/slf4j-simple/1.7.7/slf4j-simple-1.7.7.jar',
               'org/hamcrest/hamcrest-core/1.3/hamcrest-core-1.3.jar'
             ])
 
-      Helper.prepare(subject.classpath_string(:runtime).split(File::PATH_SEPARATOR))
+      _(Helper.prepare(subject.classpath_string(:runtime).split(File::PATH_SEPARATOR)))
             .must_equal Helper.prepare(example_expected)
     end
   end
@@ -166,8 +166,6 @@ def self.prepare(array)
 
     skip('TODO just use some empty jars for this spec')
 
-    skip('jruby-9.0.0.x can not require jruby core jars') if JRUBY_VERSION.match?(/9.0.0.0/)
-
     old = $CLASSPATH.to_a
 
     # sometimes the $CLASSPATH can already have BC jars
@@ -186,26 +184,26 @@ def self.prepare(array)
 
     subject.require(:runtime)
 
-    Helper.reduce($CLASSPATH.to_a, old).must_equal Helper.prepare(expected)
+    _(Helper.reduce($CLASSPATH.to_a, old)).must_equal Helper.prepare(expected)
 
     expected += example_expected
     subject.require(:compile)
-    Helper.reduce($CLASSPATH.to_a, old).must_equal Helper.prepare(expected)
+    _(Helper.reduce($CLASSPATH.to_a, old)).must_equal Helper.prepare(expected)
 
     expected << 'junit/junit/4.1/junit-4.1.jar'
     subject.require(:test)
-    Helper.reduce($CLASSPATH.to_a, old).must_equal Helper.prepare(expected)
+    _(Helper.reduce($CLASSPATH.to_a, old)).must_equal Helper.prepare(expected)
   end
 
   it 'processes Jars.lock if exists' do
     subject.instance_variable_set(:@deps, jars_lock)
 
-    Helper.prepare(subject.classpath).must_equal Helper.prepare(lock_expected_runtime)
-    Helper.prepare(subject.classpath(:compile)).must_equal Helper.prepare(lock_expected)
+    _(Helper.prepare(subject.classpath)).must_equal Helper.prepare(lock_expected_runtime)
+    _(Helper.prepare(subject.classpath(:compile))).must_equal Helper.prepare(lock_expected)
 
-    Helper.prepare(subject.classpath(:test)).must_equal Helper.prepare(lock_expected_test)
+    _(Helper.prepare(subject.classpath(:test))).must_equal Helper.prepare(lock_expected_test)
 
-    Helper.prepare(subject.classpath(:runtime)).must_equal Helper.prepare(lock_expected_runtime)
+    _(Helper.prepare(subject.classpath(:runtime))).must_equal Helper.prepare(lock_expected_runtime)
   end
 
   it 'processes Jars.lock and block loading of jars' do
@@ -214,6 +212,6 @@ def self.prepare(array)
     subject.require
 
     require_jar 'example', 'example', '1'
-    $CLASSPATH.detect { |c| c.include?('example') }.must_be_nil
+    _($CLASSPATH.detect { |c| c.include?('example') }).must_be_nil
   end
 end
diff --git a/specs/dependency_spec.rb b/specs/dependency_spec.rb
index ab3ba92..4b34190 100644
--- a/specs/dependency_spec.rb
+++ b/specs/dependency_spec.rb
@@ -7,87 +7,87 @@
 # rubocop:disable Layout/LineLength
 describe Jars::Installer::Dependency do
   it 'should parse dependency line only if it is jar or pom' do
-    Jars::Installer::Dependency.new(+'something').must_be_nil
-    Jars::Installer::Dependency.new(+'   org.apache.maven:maven-repository-metadata:jar:3.1.0:compile:/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar').wont_be_nil
-    Jars::Installer::Dependency.new(+'   org.apache.maven:maven-repository-metadata:pom:3.1.0:compile:/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar').wont_be_nil
+    assert_nil Jars::Installer::Dependency.new(+'something')
+    assert Jars::Installer::Dependency.new(+'   org.apache.maven:maven-repository-metadata:jar:3.1.0:compile:/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar')
+    assert Jars::Installer::Dependency.new(+'   org.apache.maven:maven-repository-metadata:pom:3.1.0:compile:/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar')
   end
 
   it 'should parse dependency line test scope' do
     dep = Jars::Installer::Dependency.new(+'   org.apache.maven:maven-repository-metadata:jar:3.1.0:test:/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar')
-    dep.type.must_equal :jar
-    dep.scope.must_equal :test
-    dep.gav.must_equal 'org.apache.maven:maven-repository-metadata:3.1.0'
-    dep.coord.must_equal 'org.apache.maven:maven-repository-metadata:jar:3.1.0'
-    dep.path.must_equal 'org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
-    dep.file.must_equal '/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
+    _(dep.type).must_equal :jar
+    _(dep.scope).must_equal :test
+    _(dep.gav).must_equal 'org.apache.maven:maven-repository-metadata:3.1.0'
+    _(dep.coord).must_equal 'org.apache.maven:maven-repository-metadata:jar:3.1.0'
+    _(dep.path).must_equal 'org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
+    _(dep.file).must_equal '/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
   end
 
   it 'should parse dependency line provided scope' do
     dep = Jars::Installer::Dependency.new(+'   org.apache.maven:maven-repository-metadata:jar:3.1.0:provided:/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar')
-    dep.type.must_equal :jar
-    dep.scope.must_equal :provided
-    dep.gav.must_equal 'org.apache.maven:maven-repository-metadata:3.1.0'
-    dep.coord.must_equal 'org.apache.maven:maven-repository-metadata:jar:3.1.0'
-    dep.path.must_equal 'org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
-    dep.file.must_equal '/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
+    _(dep.type).must_equal :jar
+    _(dep.scope).must_equal :provided
+    _(dep.gav).must_equal 'org.apache.maven:maven-repository-metadata:3.1.0'
+    _(dep.coord).must_equal 'org.apache.maven:maven-repository-metadata:jar:3.1.0'
+    _(dep.path).must_equal 'org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
+    _(dep.file).must_equal '/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
   end
 
   it 'should parse dependency line runtim scope' do
     dep = Jars::Installer::Dependency.new(+'   org.apache.maven:maven-repository-metadata:jar:3.1.0:compile:/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar')
-    dep.type.must_equal :jar
-    dep.scope.must_equal :runtime
-    dep.gav.must_equal 'org.apache.maven:maven-repository-metadata:3.1.0'
-    dep.coord.must_equal 'org.apache.maven:maven-repository-metadata:jar:3.1.0'
-    dep.path.must_equal 'org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
-    dep.file.must_equal '/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
+    _(dep.type).must_equal :jar
+    _(dep.scope).must_equal :runtime
+    _(dep.gav).must_equal 'org.apache.maven:maven-repository-metadata:3.1.0'
+    _(dep.coord).must_equal 'org.apache.maven:maven-repository-metadata:jar:3.1.0'
+    _(dep.path).must_equal 'org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
+    _(dep.file).must_equal '/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
 
     dep = Jars::Installer::Dependency.new(+'   org.apache.maven:maven-repository-metadata:jar:3.1.0:runtime:/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar')
-    dep.type.must_equal :jar
-    dep.scope.must_equal :runtime
-    dep.gav.must_equal 'org.apache.maven:maven-repository-metadata:3.1.0'
-    dep.coord.must_equal 'org.apache.maven:maven-repository-metadata:jar:3.1.0'
-    dep.path.must_equal 'org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
-    dep.file.must_equal '/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
+    _(dep.type).must_equal :jar
+    _(dep.scope).must_equal :runtime
+    _(dep.gav).must_equal 'org.apache.maven:maven-repository-metadata:3.1.0'
+    _(dep.coord).must_equal 'org.apache.maven:maven-repository-metadata:jar:3.1.0'
+    _(dep.path).must_equal 'org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
+    _(dep.file).must_equal '/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.jar'
   end
 
   it 'should parse pom dependency' do
     dep = Jars::Installer::Dependency.new(+'   org.apache.maven:maven-repository-metadata:pom:3.1.0:compile:/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.pom')
-    dep.type.must_equal :pom
-    dep.scope.must_equal :runtime
-    dep.gav.must_equal 'org.apache.maven:maven-repository-metadata:3.1.0'
-    dep.coord.must_equal 'org.apache.maven:maven-repository-metadata:pom:3.1.0'
-    dep.path.must_equal 'org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.pom'
-    dep.file.must_equal '/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.pom'
+    _(dep.type).must_equal :pom
+    _(dep.scope).must_equal :runtime
+    _(dep.gav).must_equal 'org.apache.maven:maven-repository-metadata:3.1.0'
+    _(dep.coord).must_equal 'org.apache.maven:maven-repository-metadata:pom:3.1.0'
+    _(dep.path).must_equal 'org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.pom'
+    _(dep.file).must_equal '/usr/local/repository/org/apache/maven/maven-repository-metadata/3.1.0/maven-repository-metadata-3.1.0.pom'
   end
 
   it 'should parse dependency where artifact_id has dots' do
     dep = Jars::Installer::Dependency.new(+'   org.eclipse.sisu:org.eclipse.sisu.plexus:jar:0.0.0.M2a:compile:/usr/local/repository/org/eclipse/sisu/org.eclipse.sisu.plexus/0.0.0.M2a/org.eclipse.sisu.plexus-0.0.0.M2a.jar')
-    dep.type.must_equal :jar
-    dep.scope.must_equal :runtime
-    dep.gav.must_equal 'org.eclipse.sisu:org.eclipse.sisu.plexus:0.0.0.M2a'
-    dep.coord.must_equal 'org.eclipse.sisu:org.eclipse.sisu.plexus:jar:0.0.0.M2a'
-    dep.path.must_equal 'org/eclipse/sisu/org.eclipse.sisu.plexus/0.0.0.M2a/org.eclipse.sisu.plexus-0.0.0.M2a.jar'
-    dep.file.must_equal '/usr/local/repository/org/eclipse/sisu/org.eclipse.sisu.plexus/0.0.0.M2a/org.eclipse.sisu.plexus-0.0.0.M2a.jar'
+    _(dep.type).must_equal :jar
+    _(dep.scope).must_equal :runtime
+    _(dep.gav).must_equal 'org.eclipse.sisu:org.eclipse.sisu.plexus:0.0.0.M2a'
+    _(dep.coord).must_equal 'org.eclipse.sisu:org.eclipse.sisu.plexus:jar:0.0.0.M2a'
+    _(dep.path).must_equal 'org/eclipse/sisu/org.eclipse.sisu.plexus/0.0.0.M2a/org.eclipse.sisu.plexus-0.0.0.M2a.jar'
+    _(dep.file).must_equal '/usr/local/repository/org/eclipse/sisu/org.eclipse.sisu.plexus/0.0.0.M2a/org.eclipse.sisu.plexus-0.0.0.M2a.jar'
   end
 
   it 'should parse dependency with classifier' do
     dep = Jars::Installer::Dependency.new(+'   org.sonatype.sisu:sisu-guice:jar:no_aop:3.1.0:compile:/usr/local/repository/org/sonatype/sisu/sisu-guice/3.1.0/sisu-guice-3.1.0-no_aop.jar')
-    dep.type.must_equal :jar
-    dep.scope.must_equal :runtime
-    dep.gav.must_equal 'org.sonatype.sisu:sisu-guice:no_aop:3.1.0'
-    dep.coord.must_equal 'org.sonatype.sisu:sisu-guice:jar:no_aop:3.1.0'
-    dep.path.must_equal 'org/sonatype/sisu/sisu-guice/3.1.0/sisu-guice-3.1.0-no_aop.jar'
-    dep.file.must_equal '/usr/local/repository/org/sonatype/sisu/sisu-guice/3.1.0/sisu-guice-3.1.0-no_aop.jar'
+    _(dep.type).must_equal :jar
+    _(dep.scope).must_equal :runtime
+    _(dep.gav).must_equal 'org.sonatype.sisu:sisu-guice:no_aop:3.1.0'
+    _(dep.coord).must_equal 'org.sonatype.sisu:sisu-guice:jar:no_aop:3.1.0'
+    _(dep.path).must_equal 'org/sonatype/sisu/sisu-guice/3.1.0/sisu-guice-3.1.0-no_aop.jar'
+    _(dep.file).must_equal '/usr/local/repository/org/sonatype/sisu/sisu-guice/3.1.0/sisu-guice-3.1.0-no_aop.jar'
   end
 
   it 'should parse dependency on windows' do
     dep = Jars::Installer::Dependency.new(+'   org.sonatype.sisu:sisu-guice:jar:no_aop:3.1.0:compile:C:\\Users\\Local\\repository\\org\\sonatype\\sisu\\sisu-guice\\3.1.0\\sisu-guice-3.1.0-no_aop.jar')
-    dep.type.must_equal :jar
-    dep.scope.must_equal :runtime
-    dep.gav.must_equal 'org.sonatype.sisu:sisu-guice:no_aop:3.1.0'
-    dep.coord.must_equal 'org.sonatype.sisu:sisu-guice:jar:no_aop:3.1.0'
-    dep.path.must_equal 'org/sonatype/sisu/sisu-guice/3.1.0/sisu-guice-3.1.0-no_aop.jar'
-    dep.file.must_equal 'C:\\Users\\Local\\repository\\org\\sonatype\\sisu\\sisu-guice\\3.1.0\\sisu-guice-3.1.0-no_aop.jar'
+    _(dep.type).must_equal :jar
+    _(dep.scope).must_equal :runtime
+    _(dep.gav).must_equal 'org.sonatype.sisu:sisu-guice:no_aop:3.1.0'
+    _(dep.coord).must_equal 'org.sonatype.sisu:sisu-guice:jar:no_aop:3.1.0'
+    _(dep.path).must_equal 'org/sonatype/sisu/sisu-guice/3.1.0/sisu-guice-3.1.0-no_aop.jar'
+    _(dep.file).must_equal 'C:\\Users\\Local\\repository\\org\\sonatype\\sisu\\sisu-guice\\3.1.0\\sisu-guice-3.1.0-no_aop.jar'
   end
 end
 # rubocop:enable Layout/LineLength
diff --git a/specs/gemspec_artifacts_spec.rb b/specs/gemspec_artifacts_spec.rb
index 2165943..f2ba2b3 100644
--- a/specs/gemspec_artifacts_spec.rb
+++ b/specs/gemspec_artifacts_spec.rb
@@ -9,16 +9,16 @@
     expected = 'group:artifact'
     line = ' group:artifact '
     ex = Jars::GemspecArtifacts::Exclusion.new(line)
-    ex.to_s.must_equal expected
+    _(ex.to_s).must_equal expected
     line = ' "group:artifact" '
     ex = Jars::GemspecArtifacts::Exclusion.new(line)
-    ex.to_s.must_equal expected
+    _(ex.to_s).must_equal expected
     line = "'group:artifact'"
     ex = Jars::GemspecArtifacts::Exclusion.new(line)
-    ex.to_s.must_equal expected
+    _(ex.to_s).must_equal expected
     line = ' group:artifact '
     ex = Jars::GemspecArtifacts::Exclusion.new("#{line} :extra:asd")
-    ex.to_s.must_equal expected
+    _(ex.to_s).must_equal expected
   end
 end
 
@@ -27,170 +27,170 @@
     expected = '[group:artifact]'
     line = ' [group:artifact] '
     ex = Jars::GemspecArtifacts::Exclusions.new(line)
-    ex.to_s.must_equal expected
+    _(ex.to_s).must_equal expected
     line = " [' group:artifact'] "
     ex = Jars::GemspecArtifacts::Exclusions.new(line)
-    ex.to_s.must_equal expected
+    _(ex.to_s).must_equal expected
     line = ' [ "group:artifact "] '
     ex = Jars::GemspecArtifacts::Exclusions.new(line)
-    ex.to_s.must_equal expected
+    _(ex.to_s).must_equal expected
     expected = '[group-id:artifact-id]'
     line = ' [ "group-id:artifact-id "] '
     ex = Jars::GemspecArtifacts::Exclusions.new(line)
-    ex.to_s.must_equal expected
+    _(ex.to_s).must_equal expected
   end
 
   it 'parse and to_s of list of exclusions' do
     expected = '[group1:artifact1, group2:artifact2]'
     line = ' [group1:artifact1, group2:artifact2] '
     ex = Jars::GemspecArtifacts::Exclusions.new(line)
-    ex.to_s.must_equal expected
+    _(ex.to_s).must_equal expected
     line = " ['group1:artifact1', ' group2:artifact2'] "
     ex = Jars::GemspecArtifacts::Exclusions.new(line)
-    ex.to_s.must_equal expected
+    _(ex.to_s).must_equal expected
     line = ' [ "group1:artifact1", " group2:artifact2"] '
     ex = Jars::GemspecArtifacts::Exclusions.new(line)
-    ex.to_s.must_equal expected
+    _(ex.to_s).must_equal expected
   end
 end
 
 describe Jars::GemspecArtifacts::Artifact do
   it 'ignore unknow type' do
-    Jars::GemspecArtifacts::Artifact.new('bla').must_be_nil
-    Jars::GemspecArtifacts::Artifact.new(' bla').must_be_nil
-    Jars::GemspecArtifacts::Artifact.new('bla bla bla').must_be_nil
+    _(Jars::GemspecArtifacts::Artifact.new('bla')).must_be_nil
+    _(Jars::GemspecArtifacts::Artifact.new(' _(bla')).must_be_nil
+    _(Jars::GemspecArtifacts::Artifact.new('bla bla _(bla')).must_be_nil
   end
 
   %i[jar pom].each do |type|
     it "parse and to_s of simple GAV #{type}" do
       expected = "#{type} g:a, 1"
       a = Jars::GemspecArtifacts::Artifact.new(expected)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} 'g:a', '1'"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} g,a,1"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} 'g',\"a\", 1"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} g:a:1"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} 'g:a:1'"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
     end
 
     it "parse and to_s of simple GAV #{type} with range" do
       expected = "#{type} g:a, [1, 2)"
       a = Jars::GemspecArtifacts::Artifact.new(expected)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} g:a:[1, 2)"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} g:a,'[1, 2)'"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} 'g', \"a\", ' [1, 2) '"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
     end
 
     it "parse and to_s of simple GAV #{type} with one exclusion" do
       expected = "#{type} g:a, 1, [a:b]"
       a = Jars::GemspecArtifacts::Artifact.new(expected)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} 'g:a', '1', '[a:b]'"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} 'g:a', '1', ['a:b']"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} g,a,1,[a:b]"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
     end
 
     it "parse and to_s of simple GAV #{type} with exclusions" do
       expected = "#{type} g:a, 1, [a:b, c:d]"
       a = Jars::GemspecArtifacts::Artifact.new(expected)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} 'g:a', '1', ['a:b', 'c:d']'"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} g,a,1,[a:b,c:d]"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
     end
 
     it "parse and to_s of simple GAV #{type} with exclusions and range" do
       expected = "#{type} g:a, (1, 2], [a:b, c:d]"
       a = Jars::GemspecArtifacts::Artifact.new(expected)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} 'g:a', '(1,2]', ['a:b', 'c:d']'"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} g,a,(1,2],[a:b,c:d]"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} g,a,(1,2],  :exclusions : [a:b,c:d]"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
     end
 
     it "parse and to_s of simple GACV #{type}" do
       expected = "#{type} g:a, c, 1"
       a = Jars::GemspecArtifacts::Artifact.new(expected)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} 'g:a', 'c', '1'"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} g,a,\"c\",1"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type}  g,a, 1  ,:classifier : c"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
     end
 
     it "parse and to_s of simple GACV #{type} with range" do
       expected = "#{type} g:a, c, [1, 2)"
       a = Jars::GemspecArtifacts::Artifact.new(expected)
-      a.to_s.must_equal expected
-      a.scope.must_be_nil
+      _(a.to_s).must_equal expected
+      _(a.scope).must_be_nil
       line = "#{type} g:a:c:[1, 2),:scope=>:runtime"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
-      a.scope.must_equal 'runtime'
+      _(a.to_s).must_equal expected
+      _(a.scope).must_equal 'runtime'
       line = "#{type} g:a:c,'[1, 2)'"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type} 'g', \"a\", 'c', ' [1, 2) '"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
       line = "#{type}  g,a,[1,  2),:classifier => c"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
     end
 
     it "parse and to_s of simple GACV #{type} with exclusions and range" do
       expected = "#{type} g:a, c, (1, 2], [a:b, c:d]"
       a = Jars::GemspecArtifacts::Artifact.new(expected)
-      a.to_s.must_equal expected
-      a.scope.must_be_nil
+      _(a.to_s).must_equal expected
+      _(a.scope).must_be_nil
       line = "#{type} 'g:a:c', '(1,2]', ['a:b', 'c:d']'"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
-      a.scope.must_be_nil
+      _(a.to_s).must_equal expected
+      _(a.scope).must_be_nil
       line = "#{type} g,a,c,(1,2],[a:b,c:d], :scope => :compile"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
-      a.scope.must_equal 'compile'
+      _(a.to_s).must_equal expected
+      _(a.scope).must_equal 'compile'
       line = "#{type}  g,a,(1,2],:classifier => c,:exclusions => [a:b,c:d]"
       a = Jars::GemspecArtifacts::Artifact.new(line)
-      a.to_s.must_equal expected
+      _(a.to_s).must_equal expected
     end
   end
 end
@@ -205,34 +205,34 @@
       eval(File.read(example_spec)) # rubocop:disable Security/Eval
     end
     artifacts = Jars::GemspecArtifacts.new(spec)
-    artifacts[0].to_s.must_equal('jar org.bouncycastle:bcpkix-jdk15on, 1.49')
-    artifacts[1].to_s.must_equal('jar org.bouncycastle:bcprov-jdk15on, 1.49')
-    artifacts[3].to_s.must_equal('jar io.dropwizard:dropwizard-logging, 0.8.0-rc5, [joda-time:joda-time]')
-    artifacts[4].to_s.must_equal('jar com.google.protobuf:protobuf-java, lite, 2.2.0')
-    artifacts[5].to_s.must_equal('jar junit:junit, 4.12')
-    artifacts[0].scope.must_be_nil
-    artifacts[1].scope.must_be_nil
-    artifacts[2].scope.must_be_nil
-    artifacts[3].scope.must_be_nil
-    artifacts[4].scope.must_be_nil
-    artifacts[5].scope.must_equal('test')
-    artifacts[0].classifier.must_be_nil
-    artifacts[1].classifier.must_be_nil
-    artifacts[2].classifier.must_be_nil
-    artifacts[3].classifier.must_be_nil
-    artifacts[4].classifier.must_equal('lite')
-    artifacts[5].classifier.must_be_nil
-    artifacts[0].exclusions.must_be_nil
-    artifacts[1].exclusions.must_be_nil
-    artifacts[2].exclusions.must_be_nil
-    artifacts[3].exclusions.to_s.must_equal('[joda-time:joda-time]')
-    artifacts[4].exclusions.must_be_nil
-    artifacts[5].exclusions.must_be_nil
+    _(artifacts[0].to_s).must_equal('jar org.bouncycastle:bcpkix-jdk15on, 1.49')
+    _(artifacts[1].to_s).must_equal('jar org.bouncycastle:bcprov-jdk15on, 1.49')
+    _(artifacts[3].to_s).must_equal('jar io.dropwizard:dropwizard-logging, 0.8.0-rc5, [joda-time:joda-time]')
+    _(artifacts[4].to_s).must_equal('jar com.google.protobuf:protobuf-java, lite, 2.2.0')
+    _(artifacts[5].to_s).must_equal('jar junit:junit, 4.12')
+    _(artifacts[0].scope).must_be_nil
+    _(artifacts[1].scope).must_be_nil
+    _(artifacts[2].scope).must_be_nil
+    _(artifacts[3].scope).must_be_nil
+    _(artifacts[4].scope).must_be_nil
+    _(artifacts[5].scope).must_equal('test')
+    _(artifacts[0].classifier).must_be_nil
+    _(artifacts[1].classifier).must_be_nil
+    _(artifacts[2].classifier).must_be_nil
+    _(artifacts[3].classifier).must_be_nil
+    _(artifacts[4].classifier).must_equal('lite')
+    _(artifacts[5].classifier).must_be_nil
+    _(artifacts[0].exclusions).must_be_nil
+    _(artifacts[1].exclusions).must_be_nil
+    _(artifacts[2].exclusions).must_be_nil
+    _(artifacts[3].exclusions.to_s).must_equal('[joda-time:joda-time]')
+    _(artifacts[4].exclusions).must_be_nil
+    _(artifacts[5].exclusions).must_be_nil
 
     artifacts.each do |a|
-      a.to_s.must_equal Jars::GemspecArtifacts::Artifact.new(a.to_s).to_s
+      _(a.to_s).must_equal Jars::GemspecArtifacts::Artifact.new(a.to_s).to_s
     end
 
-    artifacts.size.must_equal 7
+    _(artifacts.size).must_equal 7
   end
 end
diff --git a/specs/jar_installer_spec.rb b/specs/jar_installer_spec.rb
index e580a8b..c9e97e8 100644
--- a/specs/jar_installer_spec.rb
+++ b/specs/jar_installer_spec.rb
@@ -34,17 +34,17 @@ def do_install(vendor, write)
 
   it 'loads dependencies from maven' do
     deps = Jars::Installer.load_from_maven(file)
-    deps.size.must_equal 45
-    deps.each { |d| d.must_be_kind_of Jars::Installer::Dependency }
+    _(deps.size).must_equal 45
+    deps.each { |d| _(d).must_be_kind_of(Jars::Installer::Dependency) }
   end
 
   it 'generates non-vendored require-file' do
     deps = Jars::Installer.load_from_maven(file)
     Jars::Installer.write_require_jars(deps, jars)
     File.read(jars).each_line do |line|
-      line.must_match(/^\s{2}require(_jar)?\s'.+'$/) if line.size > 30 && !line.match(/^#/)
+      _(line).must_match(/^\s{2}require(_jar)?\s'.+'$/) if line.size > 30 && !line.match(/^#/)
     end
-    Dir[File.join(dir, '**')].size.must_equal 1
+    _( Dir[File.join(dir, '**')].size ).must_equal 1
   end
 
   it 'generates vendored require-file' do
@@ -52,19 +52,19 @@ def do_install(vendor, write)
     Jars::Installer.write_require_jars(deps, jars)
     Jars::Installer.vendor_jars(deps, dir)
     File.read(jars).each_line do |line|
-      line.must_match(/^\s{2}require(_jar)?\s'.+'$/) if line.size > 30 && !line.match(/^#/)
+      _(line).must_match(/^\s{2}require(_jar)?\s'.+'$/) if line.size > 30 && !line.match(/^#/)
     end
-    Dir[File.join(dir, '**', '*.jar')].size.must_equal 45
+    _( Dir[File.join(dir, '**', '*.jar')].size ).must_equal 45
   end
 
   it 'just skips install_jars and vendor_jars if there are no requirements' do
     jar = Jars::Installer.new
     jar.install_jars
     # vendor method is a mocked method
-    jar.vendor.must_be_nil
+    _(jar.vendor).must_be_nil
     jar.vendor_jars
     # vendor method is a mocked method
-    jar.vendor.must_be_nil
+    _(jar.vendor).must_be_nil
   end
 
   it 'just skips install_jars and vendor_jars if platform is not java' do
@@ -73,10 +73,10 @@ def do_install(vendor, write)
     jar = Jars::Installer.new(spec)
     jar.install_jars
     # vendor method is a mocked method
-    jar.vendor.must_be_nil
+    _(jar.vendor).must_be_nil
     jar.vendor_jars
     # vendor method is a mocked method
-    jar.vendor.must_be_nil
+    _(jar.vendor).must_be_nil
   end
 
   it 'does install_jars and vendor_jars' do
@@ -92,7 +92,7 @@ def do_install(vendor, write)
     ENV['JARS_VENDOR'] = 'true'
     jar.vendor_jars
     # vendor method is a mocked method
-    jar.vendor.must_equal 'lib'
+    _(jar.vendor).must_equal 'lib'
     java.lang.System.set_property('jars.vendor', 'false')
     jar.vendor_jars
     # vendor method is a mocked method
@@ -104,10 +104,10 @@ def do_install(vendor, write)
     Jars.reset
     jar = Jars::Installer.new(example_spec)
     result = jar.send :install_dependencies
-    result.size.must_equal 30
+    _(result.size).must_equal 30
     result.each do |d|
-      d.type.must_equal :jar
-      d.scope.must_equal :runtime
+      _(d.type).must_equal :jar
+      _(d.scope).must_equal :runtime
     end
     ENV['JARS_HOME'] = nil
   end
diff --git a/specs/jars_spec.rb b/specs/jars_spec.rb
index b880c2a..cfd4c93 100644
--- a/specs/jars_spec.rb
+++ b/specs/jars_spec.rb
@@ -5,7 +5,7 @@
 require 'stringio'
 describe Jars do
   before do
-    @env = ENV.dup
+    @env = ENV.to_h
     # helpful when debugging
     Jars.reset
   end
@@ -18,10 +18,10 @@
 
   it 'extract property' do
     ENV['SOME_JARS_HOME'] = 'bla'
-    Jars.to_prop('some_jars_home').must_equal 'bla'
+    _(Jars.to_prop('some_jars_home')).must_equal 'bla'
     if defined? JRUBY_VERSION
       java.lang.System.set_property('some.jars.home', 'blabla')
-      Jars.to_prop('some_jars_home').must_equal 'blabla'
+      _(Jars.to_prop('some_jars_home')).must_equal 'blabla'
     end
   end
 
@@ -29,12 +29,12 @@
     assert_nil Jars.to_boolean('JARS_SOMETHING')
 
     ENV['JARS_SOMETHING'] = 'falsy'
-    Jars.to_boolean('JARS_SOMETHING').must_equal false
+    _(Jars.to_boolean('JARS_SOMETHING')).must_equal false
 
     ENV[jars_verbose = 'JARS_VERBOSE'] = 'true'
-    Jars.to_boolean(jars_verbose).must_equal true
-    Jars.verbose?.must_equal true
-    jars_verbose.must_equal 'JARS_VERBOSE' # no mod
+    _(Jars.to_boolean(jars_verbose)).must_equal true
+    _(Jars.verbose?).must_equal true
+    _(jars_verbose).must_equal 'JARS_VERBOSE' # no mod
 
     if defined? JRUBY_VERSION
       jars_skip = 'JARS_SKIP'
@@ -43,12 +43,12 @@
         java.lang.System.set_property('jars.quiet', 'false')
         java.lang.System.set_property('jars.debug', '')
 
-        Jars.to_boolean(jars_skip).must_equal true
-        Jars.skip?.must_equal true
-        jars_skip.must_equal 'JARS_SKIP' # no mod
+        _(Jars.to_boolean(jars_skip)).must_equal true
+        _(Jars.skip?).must_equal true
+        _(jars_skip).must_equal 'JARS_SKIP' # no mod
 
-        Jars.to_boolean('JARS_DEBUG').must_equal true
-        Jars.to_boolean('jars.quiet').must_equal false
+        _(Jars.to_boolean('JARS_DEBUG')).must_equal true
+        _(Jars.to_boolean('jars.quiet')).must_equal false
       ensure
         java.lang.System.clear_property('jars.skip')
         java.lang.System.clear_property('jars.quiet')
@@ -58,20 +58,19 @@
   end
 
   it 'extract maven settings' do
-    settings = Jars.maven_settings
-    settings&.sub(/.*\.m2./, '')&.must_equal 'settings.xml'
+    settings = Jars.maven_settings # likely nil on CI
 
     ENV['JARS_MAVEN_SETTINGS'] = 'specs/settings.xml'
     Jars.reset
-    settings.wont_equal Jars.maven_settings
-    Jars.maven_settings.must_equal File.expand_path('specs/settings.xml')
+    _(settings).wont_equal Jars.maven_settings
+    _(Jars.maven_settings).must_equal File.expand_path('specs/settings.xml')
 
     ENV['JARS_MAVEN_SETTINGS'] = nil
 
     Jars.reset
     Dir.chdir(File.dirname(__FILE__)) do
-      settings.wont_equal Jars.maven_settings
-      Jars.maven_settings.must_equal File.expand_path('settings.xml')
+      _(settings).wont_equal Jars.maven_settings
+      _(Jars.maven_settings).must_equal File.expand_path('settings.xml')
     end
   end
 
@@ -80,13 +79,13 @@
     ENV['JARS_QUIET'] = 'true'
     ENV['JARS_MAVEN_SETTINGS'] = 'does-not-exist/settings.xml'
     home = Jars.home
-    home.must_equal(File.join(ENV['HOME'], '.m2', 'repository'))
+    _(home).must_equal(File.join(ENV['HOME'], '.m2', 'repository'))
 
     ENV['JARS_LOCAL_MAVEN_REPO'] = nil
     ENV['JARS_MAVEN_SETTINGS'] = File.join('specs', 'settings.xml')
     Jars.reset
-    Jars.home.wont_equal home
-    Jars.home.must_equal 'specs'
+    _(Jars.home).wont_equal home
+    _(Jars.home).must_equal 'specs'
 
     ENV['JARS_MAVEN_SETTINGS'] = nil
   end
@@ -97,7 +96,7 @@
     ENV.delete('HOME')
     ENV['JARS_QUIET'] = true.to_s
     ENV['JARS_MAVEN_SETTINGS'] = 'does-not-exist/settings.xml'
-    Jars.home.must_equal(File.join(env_home, '.m2', 'repository'))
+    _(Jars.home).must_equal(File.join(env_home, '.m2', 'repository'))
   end
 
   it 'determines JARS_HOME (from global settings.xml)' do
@@ -105,12 +104,12 @@
     ENV['HOME'] = "/tmp/oul'bollocks!"
     ENV['M2_HOME'] = __dir__
     ENV_JAVA['repo.path'] = 'specs'
-    Jars.home.must_equal('specs/repository')
+    _(Jars.home).must_equal('specs/repository')
     ENV['JARS_LOCAL_MAVEN_REPO'] = nil
   end
 
   it 'raises RuntimeError on requires of unknown group-id' do
-    -> { require_jar('org.something', 'slf4j-simple', '1.6.6') }.must_raise RuntimeError
+    _ { require_jar('org.something', 'slf4j-simple', '1.6.6') }.must_raise RuntimeError
   end
 
   # rubocop:disable Layout/LineLength
@@ -119,12 +118,12 @@
     Jars.reset
 
     begin
-      require_jar('org.slf4j', 'slf4j-simple') { nil }.must_equal true
+      _(require_jar('org.slf4j', 'slf4j-simple') { nil }).must_equal true
 
       $stderr = StringIO.new
-      require_jar('org.slf4j', 'slf4j-simple') { '1.6.6' }.must_equal false
+      _(require_jar('org.slf4j', 'slf4j-simple') { '1.6.6' }).must_equal false
 
-      $stderr.string.must_equal "--- jar coordinate org.slf4j:slf4j-simple already loaded with version unknown - omit version 1.6.6\n"
+      _($stderr.string).must_equal "--- jar coordinate org.slf4j:slf4j-simple already loaded with version unknown - omit version 1.6.6\n"
     ensure
       $stderr = STDERR
       ENV['JARS_HOME'] = nil
@@ -136,22 +135,22 @@
     Jars.reset
 
     begin
-      require_jar('org.slf4j', 'slf4j-simple', '1.6.6').must_equal true
+      _(require_jar('org.slf4j', 'slf4j-simple', '1.6.6')).must_equal true
       $stderr = StringIO.new
-      require_jar('org.slf4j', 'slf4j-simple') { '1.6.6' }.must_equal false
-      $stderr.string.must_equal ''
+      _(require_jar('org.slf4j', 'slf4j-simple') { '1.6.6' }).must_equal false
+      _($stderr.string).must_equal ''
 
       $stderr = StringIO.new
-      require_jar('org.slf4j', 'slf4j-simple', '1.6.4').must_equal false
-      $stderr.string.must_equal "--- jar coordinate org.slf4j:slf4j-simple already loaded with version 1.6.6 - omit version 1.6.4\n"
+      _(require_jar('org.slf4j', 'slf4j-simple', '1.6.4')).must_equal false
+      _($stderr.string).must_equal "--- jar coordinate org.slf4j:slf4j-simple already loaded with version 1.6.6 - omit version 1.6.4\n"
 
       $stderr = StringIO.new
-      require_jar('org.slf4j', 'slf4j-simple') { '1.6.4' }.must_equal false
-      $stderr.string.must_equal "--- jar coordinate org.slf4j:slf4j-simple already loaded with version 1.6.6 - omit version 1.6.4\n"
+      _(require_jar('org.slf4j', 'slf4j-simple') { '1.6.4' }).must_equal false
+      _($stderr.string).must_equal "--- jar coordinate org.slf4j:slf4j-simple already loaded with version 1.6.6 - omit version 1.6.4\n"
 
       $stderr = StringIO.new
-      require_jar('org.slf4j', 'slf4j-simple') { nil }.must_equal false
-      $stderr.string.must_equal "--- jar coordinate org.slf4j:slf4j-simple already loaded with version 1.6.6 - omit version unknown\n"
+      _(require_jar('org.slf4j', 'slf4j-simple') { nil }).must_equal false
+      _($stderr.string).must_equal "--- jar coordinate org.slf4j:slf4j-simple already loaded with version 1.6.6 - omit version unknown\n"
     ensure
       $stderr = STDERR
       ENV['JARS_HOME'] = nil
@@ -171,11 +170,11 @@
       $stderr.flush
 
       $stderr = StringIO.new
-      require_jar('org.slf4j', 'slf4j-simple', '1.6.4').must_equal true
+      _(require_jar('org.slf4j', 'slf4j-simple', '1.6.4')).must_equal true
 
-      require_jar('org.slf4j', 'slf4j-simple', '1.6.6').must_equal false
+      _(require_jar('org.slf4j', 'slf4j-simple', '1.6.6')).must_equal false
 
-      $stderr.string.must_equal "--- jar coordinate org.slf4j:slf4j-simple already loaded with version 1.6.4 - omit version 1.6.6\n"
+      _($stderr.string).must_equal "--- jar coordinate org.slf4j:slf4j-simple already loaded with version 1.6.4 - omit version 1.6.6\n"
     ensure
       $stderr = STDERR
       ENV['JARS_HOME'] = nil
@@ -192,16 +191,13 @@
 
     require_jar 'org.bouncycastle', 'bcpkix-jdk15on', JOpenSSL::BOUNCY_CASTLE_VERSION
 
-    $CLASSPATH.length.must_equal size
+    _($CLASSPATH.length).must_equal size
 
     $stderr = StringIO.new
 
     require_jar 'org.bouncycastle', 'bcpkix-jdk15on', '1.46'
 
-    $stderr.string.must_equal ''
-  rescue LoadError, NameError => e
-    p e
-    skip 'assume we have an old jruby'
+    _($stderr.string).must_equal ''
   ensure
     $stderr = STDERR
   end
@@ -219,35 +215,29 @@
     out = require_jar 'org.jruby', 'jruby-rack', '1.1.16'
     assert_nil out
 
-    $CLASSPATH.length.must_equal size
-  rescue LoadError, NameError => e
-    p e
-    skip 'assume we have an old jruby'
+    _($CLASSPATH.length).must_equal size
   end
 
   it 'does not warn on conflicts after turning into silent mode' do
+    skip('$CLASSPATH is not clean - need to skip spec') if $CLASSPATH.detect { |a| a.include?('bcpkix-jdk18on') }
+
     size = $CLASSPATH.length
-    # TODO: use jline instead to avoid this skip
-    skip('$CLASSPATH is not clean - need to skip spec') if $CLASSPATH.detect { |a| a.include?('bcpkix-jdk15on') }
 
     Jars.no_more_warnings
 
     require 'jopenssl/version'
 
-    if require_jar('org.bouncycastle', 'bcpkix-jdk15on', JOpenSSL::BOUNCY_CASTLE_VERSION)
-      $CLASSPATH.length.must_equal(size + 1)
+    if require_jar('org.bouncycastle', 'bcpkix-jdk18on', JOpenSSL::BOUNCY_CASTLE_VERSION)
+      _($CLASSPATH.length).must_equal(size + 1)
     end
 
     $stderr = StringIO.new
 
-    require_jar 'org.bouncycastle', 'bcpkix-jdk15on', '1.46'
-
-    $stderr.string.must_equal ''
+    require_jar 'org.bouncycastle', 'bcpkix-jdk18on', '1.70'
 
+    _($stderr.string).must_equal ''
+  ensure
     $stderr = STDERR
-  rescue LoadError, NameError => e
-    p e
-    skip 'assume we have an old jruby'
   end
 
   it 'no warnings on reload' do
@@ -255,8 +245,9 @@
 
     load File.expand_path('lib/jar_dependencies.rb')
 
-    $stderr.string.must_equal ''
+    _($stderr.string).must_equal ''
 
+  ensure
     $stderr = STDERR
   end
 
@@ -272,11 +263,12 @@
       require_jar 'more', 'sample', '3'
     end
 
-    $stderr.string.wont_match(/omit version 1/)
-    $stderr.string.must_match(/omit version 2/)
-    $stderr.string.must_match(/omit version 3/)
-    $stderr.string.wont_match(/omit version 4/)
+    _($stderr.string).wont_match(/omit version 1/)
+    _($stderr.string).must_match(/omit version 2/)
+    _($stderr.string).must_match(/omit version 3/)
+    _($stderr.string).wont_match(/omit version 4/)
 
+  ensure
     $stderr = STDERR
 
     $LOAD_PATH.delete(File.join(pwd, 'path'))
diff --git a/specs/maven_exec_spec.rb b/specs/maven_exec_spec.rb
index 06c57c1..ace3695 100644
--- a/specs/maven_exec_spec.rb
+++ b/specs/maven_exec_spec.rb
@@ -22,7 +22,7 @@
     Dir.chdir File.dirname(spec_with_require_relative) do
       $stderr = StringIO.new
       Jars::MavenExec.new
-      $stderr.string.must_equal ''
+      _($stderr.string).must_equal ''
     ensure
       $stderr = STDERR
     end
@@ -46,7 +46,7 @@ def spec.gem_dir
     spec.gem_dir = File.dirname(example_spec)
     # now test finding the gemspec file
     jar = Jars::MavenExec.new(spec)
-    jar.instance_variable_get(:@basedir).must_equal File.expand_path(spec.gem_dir)
-    jar.instance_variable_get(:@specfile).must_equal File.expand_path(example_spec)
+    _(jar.instance_variable_get(:@basedir)).must_equal File.expand_path(spec.gem_dir)
+    _(jar.instance_variable_get(:@specfile)).must_equal File.expand_path(example_spec)
   end
 end
diff --git a/specs/maven_factory_spec.rb b/specs/maven_factory_spec.rb
index c45d756..a248b08 100644
--- a/specs/maven_factory_spec.rb
+++ b/specs/maven_factory_spec.rb
@@ -17,36 +17,36 @@
     ENV['JARS_DEBUG'] = nil
     Jars.reset
     maven = Jars::MavenFactory.new.maven_new('pom')
-    maven.options.key?('--quiet').must_equal true
-    maven.options.key?('-X').must_equal false
-    maven.options['-Dverbose'].must_equal false
+    _(maven.options.key?('--quiet')).must_equal true
+    _(maven.options.key?('-X')).must_equal false
+    _(maven.options['-Dverbose']).must_equal false
 
     ENV['JARS_VERBOSE'] = 'true'
     ENV['JARS_DEBUG'] = nil
     Jars.reset
     maven = Jars::MavenFactory.new.maven_new('pom')
-    maven.options.key?('--quiet').must_equal false
-    maven.options.key?('-e').must_equal true
-    maven.options.key?('-X').must_equal false
-    maven.options['-Dverbose'].must_equal true
+    _(maven.options.key?('--quiet')).must_equal false
+    _(maven.options.key?('-e')).must_equal true
+    _(maven.options.key?('-X')).must_equal false
+    _(maven.options['-Dverbose']).must_equal true
 
     ENV['JARS_VERBOSE'] = nil
     ENV['JARS_DEBUG'] = 'true'
     Jars.reset
     maven = Jars::MavenFactory.new.maven_new('pom')
-    maven.options.key?('--quiet').must_equal false
-    maven.options.key?('-e').must_equal false
-    maven.options.key?('-X').must_equal true
-    maven.options['-Dverbose'].must_equal true
+    _(maven.options.key?('--quiet')).must_equal false
+    _(maven.options.key?('-e')).must_equal false
+    _(maven.options.key?('-X')).must_equal true
+    _(maven.options['-Dverbose']).must_equal true
 
     ENV['JARS_VERBOSE'] = 'true'
     ENV['JARS_DEBUG'] = 'true'
     Jars.reset
     maven = Jars::MavenFactory.new.maven_new('pom')
-    maven.options.key?('--quiet').must_equal false
-    maven.options.key?('-e').must_equal true
-    maven.options.key?('-X').must_equal true
-    maven.options['-Dverbose'].must_equal true
+    _(maven.options.key?('--quiet')).must_equal false
+    _(maven.options.key?('-e')).must_equal true
+    _(maven.options.key?('-X')).must_equal true
+    _(maven.options['-Dverbose']).must_equal true
   end
 
   it 'uses proxy settings from Gem.configuration' do
@@ -55,23 +55,23 @@
     Gem.configuration[:proxy] = 'https://localhost:3128'
     Jars.reset
     maven = Jars::MavenFactory.new.maven_new('pom')
-    maven.options.key?('-DproxySet=true').must_equal true
-    maven.options.key?('-DproxyHost=localhost').must_equal true
-    maven.options.key?('-DproxyPort=3128').must_equal true
+    _(maven.options.key?('-DproxySet=true')).must_equal true
+    _(maven.options.key?('-DproxyHost=localhost')).must_equal true
+    _(maven.options.key?('-DproxyPort=3128')).must_equal true
 
     Gem.configuration[:proxy] = :noproxy
     Jars.reset
     maven = Jars::MavenFactory.new.maven_new('pom')
-    maven.options.key?('-DproxySet=true').must_equal false
-    maven.options.key?('-DproxyHost=localhost').must_equal false
-    maven.options.key?('-DproxyPort=3128').must_equal false
+    _(maven.options.key?('-DproxySet=true')).must_equal false
+    _(maven.options.key?('-DproxyHost=localhost')).must_equal false
+    _(maven.options.key?('-DproxyPort=3128')).must_equal false
 
     ENV['JARS_MAVEN_SETTINGS'] = 'specs/settings.xml'
     Gem.configuration[:proxy] = 'https://localhost:3128'
     Jars.reset
     maven = Jars::MavenFactory.new.maven_new('pom')
-    maven.options.key?('-DproxySet=true').must_equal false
-    maven.options.key?('-DproxyHost=localhost').must_equal false
-    maven.options.key?('-DproxyPort=3128').must_equal false
+    _(maven.options.key?('-DproxySet=true')).must_equal false
+    _(maven.options.key?('-DproxyHost=localhost')).must_equal false
+    _(maven.options.key?('-DproxyPort=3128')).must_equal false
   end
 end