Change Examiner to always expect a SourceCode

Also allow `SourceCode.from` to noop if the provided source is already a
`SourceCode`

features/command_line_interface/stdin.feature

@@ -67,6 +67,7 @@ Feature: Reek reads from $stdin when no files are given
       end
       """
     Then it succeeds
+    And it reports nothing
 
 
 

lib/reek/cli/command/report_command.rb

@@ -23,8 +23,8 @@ def execute
 
         def populate_reporter_with_smells
           sources.each do |source|
-            reporter.add_examiner Examiner.new(source,
-                                               stdin_filename: options.stdin_filename,
+            reporter.add_examiner Examiner.new(Source::SourceCode.from(source),
+                                               origin: options.stdin_filename,
                                                filter_by_smells: smell_names,
                                                configuration: configuration,
                                                error_handler: LoggingErrorHandler.new)

lib/reek/examiner.rb

@@ -11,6 +11,7 @@ module Reek
   # Applies all available smell detectors to a source.
   #
   # @public
+  # :reek:TooManyInstanceVariables { max_instance_variables: 5 }
   class Examiner
     # Handles no errors
     class NullHandler
@@ -33,14 +34,16 @@ def handle(_exception)
     #   The configuration for this Examiner.
     #
     # @public
+    # :reek:ControlParameter
     # :reek:LongParameterList { max_params: 6 }
     def initialize(source,
-                   stdin_filename: nil,
+                   origin: nil,
                    filter_by_smells: [],
                    configuration: Configuration::AppConfiguration.default,
                    detector_repository_class: DetectorRepository,
                    error_handler: NullHandler.new)
-      @source              = Source::SourceCode.from(source, filename: stdin_filename)
+      @source              = Source::SourceCode.from(source)
+      @origin              = origin || @source.origin
       @smell_types         = detector_repository_class.eligible_smell_types(filter_by_smells)
       @detector_repository = detector_repository_class.new(smell_types: @smell_types,
                                                            configuration: configuration.directive_for(description))
@@ -50,17 +53,13 @@ def initialize(source,
     # @return [String] origin of the source being analysed
     #
     # @public
-    def origin
-      @origin ||= source.origin
-    end
+    attr_reader :origin
 
     # @return [String] description of the source being analysed
     #
     # @public
     # @deprecated Use origin
-    def description
-      origin
-    end
+    alias description origin
 
     #
     # @return [Array<SmellWarning>] the smells found in the source

lib/reek/source/source_code.rb

@@ -59,13 +59,13 @@ def initialize(code:, origin:, parser: self.class.default_parser)
       #
       # @return an instance of SourceCode
       # :reek:DuplicateMethodCall { max_calls: 2 }
-      # :reek:ControlParameter
-      def self.from(source, filename: nil)
+      def self.from(source)
         case source
+        when self     then source
         when File     then new(code: source.read,           origin: source.path)
-        when IO       then new(code: source.readlines.join, origin: filename || IO_IDENTIFIER)
+        when IO       then new(code: source.readlines.join, origin: IO_IDENTIFIER)
         when Pathname then new(code: source.read,           origin: source.to_s)
-        when String   then new(code: source,                origin: filename || STRING_IDENTIFIER)
+        when String   then new(code: source,                origin: STRING_IDENTIFIER)
         end
       end