Support passing array commands to format_command

The use of an array with Open3 spawns a process directly without a shell
which removes the need to escape values for a shell.

lib/kafo/puppet_command.rb

@@ -50,11 +50,21 @@ def self.aio_puppet?
       false
     end
 
+    # Format a command for use in Open3 that properly filters the environment
+    # for use with Puppet
+    #
+    # @param command [String, Array]
+    #   The command to execute. A string implies it'll run with a shell while
+    #   an array runs without. That removes the need to escape input and is
+    #   recommended.
+    # @return [Array]
+    #   A command for use in Open3
     def self.format_command(command)
+      cmd = command.is_a?(Array) ? command : [command]
       if aio_puppet?
-        [clean_env_vars, command, :unsetenv_others => true]
+        [clean_env_vars] + cmd + [:unsetenv_others => true]
       else
-        [::ENV, command, :unsetenv_others => false]
+        [::ENV] + cmd + [:unsetenv_others => false]
       end
     end
 

test/kafo/puppet_command_test.rb

@@ -118,5 +118,43 @@ module Kafo
         end
       end
     end
+
+    describe '.format_command' do
+      describe 'with Puppet AIO' do
+        specify 'with a string' do
+          PuppetCommand.stub(:aio_puppet?, true) do
+            PuppetCommand.stub(:clean_env_vars, {'FOO' => 'bar'}) do
+              expected = [{'FOO' => 'bar'}, 'echo hello world', { :unsetenv_others => true }]
+              assert_equal(expected, PuppetCommand.format_command('echo hello world'))
+            end
+          end
+        end
+
+        specify 'with an array' do
+          PuppetCommand.stub(:aio_puppet?, true) do
+            PuppetCommand.stub(:clean_env_vars, {'FOO' => 'bar'}) do
+              expected = [{'FOO' => 'bar'}, 'echo', 'hello', 'world', { :unsetenv_others => true }]
+              assert_equal(expected, PuppetCommand.format_command(['echo', 'hello', 'world']))
+            end
+          end
+        end
+      end
+
+      describe 'with regular Puppet' do
+        specify 'with a string' do
+          PuppetCommand.stub(:aio_puppet?, false) do
+            expected = [::ENV, 'echo hello world', { :unsetenv_others => false }]
+            assert_equal(expected, PuppetCommand.format_command('echo hello world'))
+          end
+        end
+
+        specify 'with an array' do
+          PuppetCommand.stub(:aio_puppet?, false) do
+            expected = [::ENV, 'echo', 'hello', 'world', { :unsetenv_others => false }]
+            assert_equal(expected, PuppetCommand.format_command(['echo', 'hello', 'world']))
+          end
+        end
+      end
+    end
   end
 end