Add input plugin type API

Signed-off-by: Clinton Wolfe <clintoncwolfe@gmail.com>

lib/inspec/plugin/v2/plugin_types/input.rb

@@ -1,5 +1,37 @@
 module Inspec::Plugin::V2::PluginType
   class Input < Inspec::Plugin::V2::PluginBase
     register_plugin_type(:input)
+
+    #====================================================================#
+    #                         Input plugin type API
+    #====================================================================#
+    # Implementation classes must implement these methods.
+
+    # When an input is obtained from the plugin, this number determines what
+    # precedence to assign to the input.
+    # @return Integer range 0-100. Higher priority means higher precedence
+    def default_priority
+      60
+    end
+
+    # Indicates an attempt is being made to read the value for an input.
+    # Return nil or an Event if the plugin is choosing to respond with a value.
+    # Note that the Input system will still log the attempt in the event log,
+    # even if nil is returned.
+    # If you wish to indicate nil as a value for the input, return an
+    # Event explicitly setting value to nil.
+    # @return Inspec::Input::Event
+    def fetch(_profile_name, _input_name)
+      raise NotImplementedError, "Plugin #{plugin_name} must implement the #fetch method"
+    end
+
+    # Given a profile name, list all input names for which the plugin
+    # would offer a response.
+    # @param String profile_name Name of the profile
+    # @return Array[String] List of input names for which the plugin
+    # would offer a response.
+    def list_inputs(_profile)
+      raise NotImplementedError, "Plugin #{plugin_name} must implement the #list_inputs method"
+    end
   end
 end

test/unit/plugin/v2/api_input.rb

@@ -22,13 +22,14 @@ describe 'Input plugin type' do
 
   describe 'when examining the specific plugin type API' do
     [
-      # TODO - API instance methods
-      # fetch?
-      # default_priority?
+      # API instance methods
+      :fetch,
+      :default_priority,
+      :list_inputs,
     ].each do |api_method|
-      it "should define an #{api_method} in the superclass" do
-        klass = Inspec::Plugin::V2::PluginType::CliCommand
-        klass.method_defined?(api_method).must_eq true
+      it "should define a '#{api_method}' method in the superclass" do
+        klass = Inspec::Plugin::V2::PluginType::Input
+        klass.method_defined?(api_method).must_equal true
       end
     end
   end