brew ln --force is now brew ln --overwrite

* Renames --force to --overwrite, freeing up brew ln --force for Homebrew/homebrew#13349
* Changes --dry-run to preview linking by default, rather than
  overwriting. An overwrite dry-run can be simulated via both
  --dry-run --overwrite
* Adds some basic Keg tests

1 files changed, 13 insertions, 5 deletions

diff --git a/Library/Homebrew/cmd/link.rb b/Library/Homebrew/cmd/link.rb
index 8e942cd91..66d8e9583 100644
--- a/Library/Homebrew/cmd/link.rb
+++ b/Library/Homebrew/cmd/link.rb
@@ -1,3 +1,5 @@
+require 'ostruct'
+
 module Homebrew extend self
 
   def link
@@ -7,10 +9,10 @@ module Homebrew extend self
       raise "Cowardly refusing to `sudo brew link'\n#{SUDO_BAD_ERRMSG}"
     end
 
-    if ARGV.force? then mode = :force
-    elsif ARGV.dry_run? then mode = :dryrun
-    else mode = nil
-    end
+    mode = OpenStruct.new
+
+    mode.overwrite = true if ARGV.include? '--overwrite'
+    mode.dry_run = true if ARGV.dry_run?
 
     ARGV.kegs.each do |keg|
       if keg.linked?
@@ -18,12 +20,18 @@ module Homebrew extend self
         next
       end
 
-      if mode == :dryrun
+      if mode.dry_run and mode.overwrite
         print "Would remove:\n" do
           keg.link(mode)
         end
 
         next
+      elsif mode.dry_run
+        print "Would link:\n" do
+          keg.link(mode)
+        end
+
+        next
       end
 
       print "Linking #{keg}... " do