Enable caching for backend calls

inspec.gemspec

@@ -26,7 +26,7 @@ Gem::Specification.new do |spec|
 
   spec.required_ruby_version = '>= 2.3'
 
-  spec.add_dependency 'train', '~> 0.29', '>= 0.29.2'
+  spec.add_dependency 'train', '~> 0.30'
   spec.add_dependency 'thor', '~> 0.19'
   spec.add_dependency 'json', '>= 1.8', '< 3.0'
   spec.add_dependency 'rainbow', '~> 2'

lib/inspec/backend.rb

@@ -53,6 +53,18 @@ def self.create(config)
         raise "Can't connect to transport backend '#{name}'."
       end
 
+      # Set caching settings. We always want to enable caching for
+      # the Mock transport for testing.
+      if config[:backend_cache] || config[:backend] == :mock
+        connection.enable_cache(:file)
+        connection.enable_cache(:command)
+      elsif config[:debug_shell]
+        connection.disable_cache(:file)
+        connection.disable_cache(:command)
+      else
+        connection.disable_cache(:command)
+      end
+
       cls = Class.new do
         include Base
 

lib/inspec/base_cli.rb

@@ -67,6 +67,8 @@ def self.exec_options
         desc: 'Use the given path for caching dependencies. (default: ~/.inspec/cache)'
       option :create_lockfile, type: :boolean, default: true,
         desc: 'Write out a lockfile based on this execution (unless one already exists)'
+      option :backend_cache, type: :boolean, default: false,
+        desc: 'Allow caching for backend command output.'
     end
 
     private

lib/inspec/cli.rb

@@ -189,6 +189,7 @@ def detect
   def shell_func
     diagnose
     o = opts.dup
+    o[:debug_shell] = true
 
     json_output = ['json', 'json-min'].include?(opts['format'])
     log_device = json_output ? nil : STDOUT

test/functional/inspec_shell_test.rb

@@ -14,6 +14,16 @@ def do_shell_c(code, exit_status, json = false, stderr = '')
       out
     end
 
+    it 'confirm file caching is disabled' do
+      out = do_shell_c('inspec.backend.cache_enabled?(:file)', 0)
+      out.stdout.chop.must_equal 'false'
+    end
+
+    it 'confirm command caching is disabled' do
+      out = do_shell_c('inspec.backend.cache_enabled?(:command)', 0)
+      out.stdout.chop.must_equal 'false'
+    end
+
     it 'can run ruby expressions (json output)' do
       x = rand
       y = rand

test/unit/runner_test.rb

@@ -11,6 +11,29 @@
       Inspec::Runner.any_instance.stubs(:validate_attributes_file_readability!)
     end
 
+    describe 'when backend caching is enabled' do
+      it 'returns a backend with caching' do
+        opts = { backend_cache: true }
+        runner = Inspec::Runner.new(opts)
+        backend = runner.instance_variable_get(:@backend)
+        backend.backend.cache_enabled?(:command).must_equal true
+      end
+    end
+
+    describe 'when backend caching is disabled' do
+      it 'returns a backend without caching' do
+        opts = { backend_cache: false }
+        runner = Inspec::Runner.new(opts)
+        backend = runner.instance_variable_get(:@backend)
+        backend.backend.cache_enabled?(:command).must_equal false
+      end
+
+      it 'returns a backend without caching as default' do
+        backend = runner.instance_variable_get(:@backend)
+        backend.backend.cache_enabled?(:command).must_equal false
+      end
+    end
+
     describe 'when no attrs are specified' do
       it 'returns an empty hash' do
         options = {}