Check for more edge cases when parsing options and display help when …

…requested or options are invalid

features/help.feature

@@ -0,0 +1,60 @@
+Feature: get help on using trout
+
+  Scenario Outline: Specify an unknown command
+    When I run "trout <arguments>"
+    Then the output should contain:
+      """
+      I don't know how to "<command>."
+      Run "trout help" for usage information.
+      """
+    Examples:
+      | arguments | command |
+      | swim      | swim    |
+      | help swim | swim    |
+
+  Scenario Outline: Run an invalid command
+    When I run "<invalid command>"
+    Then the output should contain:
+      """
+      I don't understand the options you provided.
+      Run "<help command>" for usage information.
+      """
+    Examples:
+      | invalid command               | help command        |
+      | trout checkout                | trout help checkout |
+      | trout checkout file           | trout help checkout |
+      | trout checkout file url extra | trout help checkout |
+      | trout update                  | trout help update   |
+      | trout update file extra       | trout help update   |
+
+  Scenario Outline: Ask for help
+    When I run "<help command>"
+    Then the output should contain:
+      """
+      trout helps you sync individual files from other git repositories.
+      """
+    And the output should contain:
+      """
+      Commands:
+      """
+    And the output should not contain:
+      """
+      I don't know how
+      """
+    Examples:
+      | help command |
+      | trout        |
+      | trout help   |
+      | trout -h     |
+      | trout --help |
+
+  Scenario Outline: Ask for usage for a particular command
+    When I run "trout help <command>"
+    Then the output should contain:
+      """
+      Usage: trout <command> <usage>
+      """
+    Examples:
+      | command  | usage            |
+      | checkout | filename git_url |
+      | update   | filename         |

features/sync_gemfile.feature

@@ -78,3 +78,4 @@ Feature: sync a Gemfile between two repositories
       gem "mysql"
       gem "redcloth"
       """
+

lib/trout/cli.rb

@@ -1,3 +1,4 @@
+require 'optparse'
 require 'trout/managed_file'
 
 module Trout
@@ -6,31 +7,104 @@ def self.run(arguments)
       new(arguments).run
     end
 
-    attr_reader :arguments, :git_url, :filename, :file, :command
+    attr_accessor :command, :option_parser, :arguments, :file
 
     def initialize(arguments)
-      self.arguments = arguments
-      self.file = ManagedFile.new(filename)
+      self.arguments     = arguments
+      self.option_parser = parse_options
     end
 
     def run
       case command
       when 'checkout'
-        self.git_url = arguments[2]
+        build_file
+        git_url = next_argument
+        end_arguments
         file.copy_from(git_url)
       when 'update'
+        build_file
+        end_arguments
         file.update
+      when 'help', nil
+        puts option_parser
+        if arguments_left?
+          puts
+          usage_for(next_argument)
+        end
+      else
+        unknown_command(command)
       end
     end
 
     private
 
-    def arguments=(arguments)
-      @arguments    = arguments
-      self.command  = arguments[0]
-      self.filename = arguments[1]
+    def parse_options
+      option_parser = OptionParser.new do |parser|
+        parser.banner =
+          "trout helps you sync individual files from other git repositories.\n\n" +
+          "Usage: trout [options] command arguments"
+
+        parser.separator ""
+        parser.separator "Options:"
+        parser.separator ""
+
+        parser.on("-h", "--help", "View this help document")
+
+        parser.separator ""
+        parser.separator "Commands:"
+        parser.separator ""
+        parser.separator "  checkout - start tracking a file from another repository"
+        parser.separator "  help     - get usage details for a specific command"
+        parser.separator "  update   - synchronize changes to a tracked file"
+      end
+
+      option_parser.parse!(arguments)
+
+      if arguments_left?
+        self.command = next_argument
+      else
+        self.command = 'help'
+      end
+
+      option_parser
+    end
+
+    def next_argument
+      arguments.shift or invalid_arguments
     end
 
-    attr_writer :git_url, :filename, :file, :command
+    def arguments_left?
+      !arguments.empty?
+    end
+
+    def invalid_arguments
+      puts "I don't understand the options you provided."
+      puts %{Run "trout help #{command}" for usage information.}
+      exit
+    end
+
+    def end_arguments
+      invalid_arguments if arguments_left?
+    end
+
+    def build_file
+      self.file = ManagedFile.new(next_argument)
+    end
+
+    def usage_for(command)
+      case command
+      when 'checkout'
+        puts "Usage: trout checkout filename git_url"
+      when 'update'
+        puts "Usage: trout update filename"
+      else
+        unknown_command(command)
+      end
+    end
+
+    def unknown_command(command)
+      puts %{I don't know how to "#{command}."}
+      puts %{Run "trout help" for usage information.}
+    end
   end
 end