Introduce customizable error descriptions.

bin/bacon

@@ -7,6 +7,7 @@ module Bacon; end
 
 automatic = false
 output = 'SpecDoxOutput'
+error  = 'InlineErrorDescription'
 
 options = OptionParser.new("", 24, '  ') { |opts|
   opts.banner = "Usage: bacon [options] [files | -a] [-- untouched arguments]"
@@ -57,6 +58,22 @@ options = OptionParser.new("", 24, '  ') { |opts|
           "do FORMAT (SpecDox/TestUnit/Tap) output") { |format|
     output = format + "Output" 
   }
+
+  opts.on("-i", "--inline",  "show errors inlined (default)") {
+    error = 'InlineErrorDescription'
+  }
+  opts.on("-l", "--newline", "show errors with newlines") {
+    error = 'NewlineErrorDescription'
+  }
+  opts.on("-f", "--diff",    "show errors with diff command") {
+    error = 'DiffErrorDescription'
+  }
+
+  opts.on("--error DESCRIPTOR",
+          "show errors with DESCRIPTOR (Inline/Newline/Diff)") { |descriptor|
+    error = descriptor + "ErrorDescription"
+  }
+
   opts.on("-Q", "--no-backtrace", "don't print backtraces") {
     Bacon.const_set :Backtraces, false
   }
@@ -110,6 +127,7 @@ end
 require 'bacon'
 
 Bacon.extend Bacon.const_get(output) rescue abort "No such formatter: #{output}"
+Bacon.extend Bacon.const_get(error) rescue abort "No such error descriptor: #{error}"
 Bacon.summary_on_exit
 
 files.each { |file|

lib/bacon.rb

@@ -121,6 +121,42 @@ def handle_summary;  end
 
   extend SpecDoxOutput          # default
 
+  module InlineErrorDescription
+    def handle_error_description negated, object, name, args
+      desc = negated ? "not " : ""
+      desc << object.inspect << "." << name
+      desc << "(" << args.map{|x|x.inspect}.join(", ") << ") failed"
+    end
+  end
+
+  module NewlineErrorDescription
+    def handle_error_description negated, object, name, args
+      desc = negated ? "not " : ""
+      desc << "\n#{object.inspect}\n.#{name}(\n"
+      desc << args.map{|x|x.inspect}.join(",\n") << "\n) failed"
+    end
+  end
+
+  module DiffErrorDescription
+    def handle_error_description negated, object, name, args
+      require 'tempfile'
+      desc = negated ? "not " : ""
+      Tempfile.open('expect') do |expect|
+        Tempfile.open('was') do |was|
+          expect.puts(object.to_s)
+          expect.close
+          was.puts(args.map{|x|x.to_s}.join(",\n"))
+          was.close
+          desc << "#{object.class}##{name}(\n"
+          desc << `diff #{expect.path} #{was.path}`
+        end
+      end
+      desc << ") failed"
+    end
+  end
+
+  extend InlineErrorDescription # default
+
   class Error < RuntimeError
     attr_accessor :count_as
 
@@ -334,11 +370,7 @@ def satisfy(description="", &block)
 
   def method_missing(name, *args, &block)
     name = "#{name}?"  if name.to_s =~ /\w[^?]\z/
-
-    desc = @negated ? "not " : ""
-    desc << @object.inspect << "." << name.to_s
-    desc << "(" << args.map{|x|x.inspect}.join(", ") << ") failed"
-
+    desc = Bacon.handle_error_description(@negated, @object, name.to_s, args)
     satisfy(desc) { |x| x.__send__(name, *args, &block) }
   end