Default to watchexec when installed

exe/retest

@@ -12,7 +12,6 @@ Signal.trap(:INT) do
 end
 
 options = Retest::Options.new(ARGV)
-puts "Watcher: [#{options.watcher.upcase}]"
 
 if options.help?
   $stdout.puts options.help
@@ -28,8 +27,14 @@ prompt     = Retest::Prompt.new
 repository = Retest::Repository.new(files: Retest::VersionControl.files, prompt: prompt)
 command    = Retest::Command.for_options(options)
 runner     = Retest::Runner.new(command)
-watcher    = Retest::Watcher.for(options.watcher)
 sounds     = Retest::Sounds.for(options)
+watcher    = Retest::Watcher.for(options.watcher).tap do |tool|
+  if tool == Retest::Watcher::Watchexec
+    puts "Watcher: [WATCHEXEC]"
+  else Retest::Watcher::Default
+    puts "Watcher: [LISTEN]"
+  end
+end
 
 sounds.play(:start)
 runner.add_observer(sounds)

lib/retest/options.rb

@@ -169,7 +169,7 @@ def extensions
     end
 
     def watcher
-      params[:watcher] || :listen
+      params[:watcher] || :installed
     end
 
     def merge(options = [])

lib/retest/watcher.rb

@@ -2,8 +2,9 @@ module Retest
   module Watcher
     def self.for(watcher)
       tool = case watcher.to_s
-        when 'listen'    then Default
-        when 'watchexec' then Watchexec
+        when 'listen'        then Default
+        when 'watchexec'     then Watchexec
+        when '', 'installed' then installed
         else                  raise ArgumentError, "Unknown #{watcher}"
         end
 
@@ -14,6 +15,10 @@ def self.for(watcher)
       tool
     end
 
+    def self.installed
+      [Watchexec, Default].find(&:installed?)
+    end
+
     module Default
       def self.installed?
         true

test/retest/options_test.rb

@@ -82,10 +82,10 @@ def test_listener
       assert_equal :listen, @subject.watcher
 
       @subject.args = %w[-w hello]
-      assert_equal :listen, @subject.watcher
+      assert_equal :installed, @subject.watcher
 
       @subject.args = %w[] # default when no listeners are install by default
-      assert_equal :listen, @subject.watcher
+      assert_equal :installed, @subject.watcher
     end
   end
 end

test/retest/watcher_test.rb

@@ -5,8 +5,9 @@ class TestWatcher < Minitest::Test
     def test_for
       assert_equal Watcher::Default, Watcher.for('listen')
       assert_equal Watcher::Watchexec, Watcher.for('watchexec')
+      assert_equal Watcher::Watchexec, Watcher.for(nil)
 
-      assert_raises(ArgumentError) { Watcher.for(nil) }
+      assert_raises(ArgumentError) { Watcher.for('fswatch') }
     end
   end