Marshalize mismatch errors

Implements functionality to make MismatchErrors Marshalizeable.

lib/scientist/experiment.rb

@@ -84,6 +84,7 @@ def raise_on_mismatches?
   #
   # Returns the configured block.
   def before_run(&block)
+    marshalize(block)
     @_scientist_before_run = block
   end
 
@@ -99,6 +100,7 @@ def behaviors
   #
   # Returns the configured block.
   def clean(&block)
+    marshalize(block)
     @_scientist_cleaner = block
   end
 
@@ -131,6 +133,7 @@ def clean_value(value)
   #
   # Returns the block.
   def compare(*args, &block)
+    marshalize(block)
     @_scientist_comparator = block
   end
 
@@ -141,6 +144,7 @@ def compare(*args, &block)
   #
   # Returns the block.
   def compare_errors(*args, &block)
+    marshalize(block)
     @_scientist_error_comparator = block
   end
 
@@ -159,6 +163,7 @@ def context(context = nil)
   #
   # This can be called more than once with different blocks to use.
   def ignore(&block)
+    marshalize(block)
     @_scientist_ignores ||= []
     @_scientist_ignores << block
   end
@@ -251,6 +256,7 @@ def run(name = nil)
 
   # Define a block that determines whether or not the experiment should run.
   def run_if(&block)
+    marshalize(block)
     @_scientist_run_if_block = block
   end
 
@@ -276,6 +282,7 @@ def should_experiment_run?
 
   # Register a named behavior for this experiment, default "candidate".
   def try(name = nil, &block)
+    marshalize(block)
     name = (name || "candidate").to_s
 
     if behaviors.include?(name)
@@ -287,6 +294,7 @@ def try(name = nil, &block)
 
   # Register the control behavior for this experiment.
   def use(&block)
+    marshalize(block)
     try "control", &block
   end
 
@@ -318,4 +326,12 @@ def generate_result(name)
     control = observations.detect { |o| o.name == name }
     Scientist::Result.new(self, observations, control)
   end
+
+  private
+
+  def marshalize(block)
+    def block._dump(_)
+      to_s
+    end
+  end
 end

test/scientist/experiment_test.rb

@@ -491,6 +491,27 @@ def @ex.raised(op, exception)
       assert_raises(Scientist::Experiment::MismatchError) { runner.call }
     end
 
+    it "can be marshaled" do
+      Fake.raise_on_mismatches = true
+      @ex.before_run { "some block" }
+      @ex.clean { "some block" }
+      @ex.compare_errors { "some block" }
+      @ex.ignore { false }
+      @ex.run_if { "some block" }
+      @ex.try { "candidate" }
+      @ex.use { "control" }
+      @ex.compare { |control, candidate| control == candidate }
+
+      mismatch = nil
+      begin
+        @ex.run
+      rescue Scientist::Experiment::MismatchError => e
+        mismatch = e
+      end
+
+      assert_kind_of(String, Marshal.dump(mismatch))
+    end
+
     describe "#raise_on_mismatches?" do
       it "raises when there is a mismatch if the experiment instance's raise on mismatches is enabled" do
         Fake.raise_on_mismatches = false