diff --git a/Gemfile b/Gemfile
index 7e5afeb..d3fdb90 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,3 +5,4 @@ gem "rspec"
 gem "rdoc"
 gem "redcarpet"
 gem "syntax"
+gem "simplecov"
diff --git a/Gemfile.lock b/Gemfile.lock
index 7cca6be..535c103 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,6 +2,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     diff-lcs (1.5.0)
+    docile (1.4.0)
     psych (5.1.0)
       stringio
     rake (13.0.6)
@@ -21,6 +22,12 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.12.0)
     rspec-support (3.12.1)
+    simplecov (0.22.0)
+      docile (~> 1.1)
+      simplecov-html (~> 0.11)
+      simplecov_json_formatter (~> 0.1)
+    simplecov-html (0.12.3)
+    simplecov_json_formatter (0.1.4)
     stringio (3.0.7)
     syntax (1.2.2)
 
@@ -32,6 +39,7 @@ DEPENDENCIES
   rdoc
   redcarpet
   rspec
+  simplecov
   syntax
 
 BUNDLED WITH
diff --git a/Rakefile b/Rakefile
index aa97e1d..c7a43af 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,5 +1,8 @@
+require "rake/clean"
 require "rspec/core/rake_task"
 
+CLEAN.include %w[spec/run gen .yardoc yard coverage dist]
+
 task :build_dist do
   sh "ruby rb/build_dist.rb"
 end
diff --git a/spec/propane_spec.rb b/spec/propane_spec.rb
index 5467f9a..06ca243 100644
--- a/spec/propane_spec.rb
+++ b/spec/propane_spec.rb
@@ -4,19 +4,52 @@ require "open3"
 Results = Struct.new(:stdout, :stderr, :status)
 
 describe Propane do
+  before(:all) do
+    @statics = {}
+  end
+
   def write_grammar(grammar, options = {})
     options[:name] ||= ""
     File.write("spec/run/testparser#{options[:name]}.propane", grammar)
   end
 
   def build_parser(options = {})
-    options[:name] ||= ""
+    @statics[:build_test_id] ||= 0
+    @statics[:build_test_id] += 1
     if ENV["dist_specs"]
-      propane = "dspec/propane"
+      command = %W[dist/propane]
     else
-      propane = "./propane.sh"
+      command = %W[ruby -I spec/run -r _simplecov_setup -I lib bin/propane]
+      command_prefix =
+        if ENV["partial_specs"]
+          "p"
+        else
+          "b"
+        end
+      command_name = "#{command_prefix}#{@statics[:build_test_id]}"
+      File.open("spec/run/_simplecov_setup.rb", "w") do |fh|
+        fh.puts <<EOF
+require "bundler"
+Bundler.setup
+require "simplecov"
+class MyFormatter
+  def format(*args)
+  end
+end
+SimpleCov.start do
+  command_name(#{command_name.inspect})
+  filters.clear
+  add_filter do |src|
+    !(src.filename[SimpleCov.root])
+  end
+  formatter(MyFormatter)
+end
+# force color off
+ENV["TERM"] = nil
+EOF
+      end
     end
-    command = %W[#{propane} spec/run/testparser#{options[:name]}.propane spec/run/testparser#{options[:name]}.#{options[:language]} --log spec/run/testparser#{options[:name]}.log]
+    command += %W[spec/run/testparser#{options[:name]}.propane spec/run/testparser#{options[:name]}.#{options[:language]} --log spec/run/testparser#{options[:name]}.log]
     if (options[:capture])
       stdout, stderr, status = Open3.capture3(*command)
       Results.new(stdout, stderr, status)
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 9835d82..5b169b9 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,11 +1,27 @@
-require "bundler/setup"
-require "propane"
+unless ENV["dist_specs"]
+  require "bundler/setup"
+  require "simplecov"
 
-RSpec.configure do |config|
-  # Enable flags like --only-failures and --next-failure
-  config.example_status_persistence_file_path = ".rspec_status"
+  SimpleCov.start do
+    add_filter "/spec/"
+    add_filter "/.bundle/"
+    if ENV["partial_specs"]
+      command_name "RSpec-partial"
+    else
+      command_name "RSpec"
+    end
+    project_name "Propane"
+    merge_timeout 3600
+  end
 
-  config.expect_with :rspec do |c|
-    c.syntax = :expect
+  RSpec.configure do |config|
+    # Enable flags like --only-failures and --next-failure
+    config.example_status_persistence_file_path = ".rspec_status"
+
+    config.expect_with :rspec do |c|
+      c.syntax = :expect
+    end
   end
 end
+
+require "propane"