1 files changed, 54 insertions, 0 deletions
diff --git a/spec/mspec/lib/mspec/runner/evaluate.rb b/spec/mspec/lib/mspec/runner/evaluate.rb
new file mode 100644
index 0000000000..fded84421f
--- /dev/null
+++ b/spec/mspec/lib/mspec/runner/evaluate.rb
@@ -0,0 +1,54 @@
+class SpecEvaluate
+  def self.desc=(desc)
+    @desc = desc
+  end
+
+  def self.desc
+    @desc ||= "evaluates "
+  end
+
+  def initialize(ruby, desc)
+    @ruby = ruby.rstrip
+    @desc = desc || self.class.desc
+  end
+
+  # Formats the Ruby source code for reabable output in the -fs formatter
+  # option. If the source contains no newline characters, wraps the source in
+  # single quotes to set if off from the rest of the description string. If
+  # the source does contain newline characters, sets the indent level to four
+  # characters.
+  def format(ruby, newline=true)
+    if ruby.include?("\n")
+      lines = ruby.each_line.to_a
+      if /( *)/ =~ lines.first
+        if $1.size > 4
+          dedent = $1.size - 4
+          ruby = lines.map { |l| l[dedent..-1] }.join
+        else
+          indent = " " * (4 - $1.size)
+          ruby = lines.map { |l| "#{indent}#{l}" }.join
+        end
+      end
+      "\n#{ruby}"
+    else
+      "'#{ruby.lstrip}'"
+    end
+  end
+
+  def define(&block)
+    ruby = @ruby
+    desc = @desc
+    evaluator = self
+
+    specify "#{desc} #{format ruby}" do
+      evaluator.instance_eval(ruby)
+      evaluator.instance_eval(&block)
+    end
+  end
+end
+
+class Object
+  def evaluate(str, desc=nil, &block)
+    SpecEvaluate.new(str, desc).define(&block)
+  end
+end