Correctly handle duplicate new friends/locations when editing

Fixes #199

lib/friends/introvert.rb

@@ -43,11 +43,17 @@ def clean(clean_command:)
       # locations.
       (@activities + @notes).each do |event|
         event.friend_names.each do |name|
-          add_friend(name: name) unless friend_names.include? name
+          unless friend_names.include? name
+            add_friend(name: name)
+            friend_names << name
+          end
         end
 
         event.location_names.each do |name|
-          add_location(name: name) unless location_names.include? name
+          unless location_names.include? name
+            add_location(name: name)
+            location_names << name
+          end
         end
       end
 

test/commands/edit_spec.rb

@@ -81,6 +81,7 @@
 - 2015-11-01: **Grace Hopper** and I went to _Marie's Diner_. George had to cancel at the last minute. @food
 - 2015-01-04: Got lunch with **Grace Hopper** and **George Washington Carver**. @food
 - 2014-12-31: Celebrated the new year in _Paris_ with **Marie Curie**. @partying
+- 2014-12-16: Okay, yep, I definitely just saw **Bigfoot** in the _Mysterious Mountains_!
 - 2014-12-15: I just had a possible **Bigfoot** sighting! I think I may have seen **Bigfoot** in the _Mysterious Mountains_.
 - 2014-11-15: Talked to **George Washington Carver** on the phone for an hour.
 

test/editor

@@ -9,7 +9,13 @@ filename = ARGV[0]
 current_file_contents = File.read(filename).split("\n")
 File.open(filename, "w") do |file|
   file.puts current_file_contents[0]
+
+  # We add two activities that contain the same new friend and new
+  # location, to test that this doesn't crash `friends edit` as
+  # previously happened.
   file.puts "- 2014-12-15: I just had a possible **Bigfoot** sighting! "\
             "I think I may have seen **Bigfoot** in the _Mysterious Mountains_."
+  file.puts "- 2014-12-16: Okay, yep, I definitely just saw **Bigfoot** in "\
+            "the _Mysterious Mountains_!"
   file.puts current_file_contents.drop(1)
 end