Move common lock test behavior out of mutex spec into module.

spec/process_shared/lock_behavior.rb

@@ -0,0 +1,60 @@
+module ProcessShared
+  # Classes that include this module should assign a lock object to
+  # @lock before each test.
+  module LockBehavior
+
+    # Fork +n+ processes.  In each, yield the block (passing the process
+    # number), then call Kernel.exit!  Waits for all processes to
+    # complete before returning.
+    def fork_many(n)
+      pids = []
+      n.times do |i|
+        pids << fork do
+          yield i
+          Kernel.exit!
+        end
+      end
+
+      pids.each { |pid| ::Process.wait(pid) }
+    end
+
+    def test_protects_access_to_a_shared_variable
+      mem = SharedMemory.new(:char)
+      mem.put_char(0, 0)
+
+      fork_many(10) do |i|
+        inc = (-1) ** i       # half the procs increment; half decrement
+        10.times do
+          @lock.lock
+          begin
+            mem.put_char(0, mem.get_char(0) + inc)
+            sleep 0.001
+          ensure
+            @lock.unlock
+          end
+        end
+      end
+
+      mem.get_char(0).must_equal(0)
+    end
+
+    def test_protects_access_to_a_shared_variable_with_synchronize
+      mem = SharedMemory.new(:char)
+      mem.put_char(0, 0)
+
+      fork_many(10) do |i|
+        inc = (-1) ** i         # half the procs increment; half decrement
+        10.times do
+          @lock.synchronize do
+            mem.put_char(0, mem.get_char(0) + inc)
+            sleep 0.001
+          end
+        end
+      end
+
+      mem.get_char(0).must_equal(0)
+    end
+
+
+  end
+end

spec/process_shared/mutex_spec.rb

@@ -1,81 +1,35 @@
 require 'spec_helper'
 require 'process_shared'
 
+require 'process_shared/lock_behavior'
+
 module ProcessShared
   describe Mutex do
-    it 'protects access to a shared variable' do
-      mutex = Mutex.new
-      mem = SharedMemory.new(:char)
-      mem.put_char(0, 0)
 
-      pids = []
-      10.times do |i|
-        inc = (-1) ** i         # half the procs increment; half decrement
-        pids << fork do
-          10.times do
-            mutex.lock
-            begin
-              mem.put_char(0, mem.get_char(0) + inc)
-              sleep 0.001
-            ensure
-              mutex.unlock
-            end
-          end
-          Kernel.exit!
-        end
-      end
+    include LockBehavior
 
-      pids.each { |pid| ::Process.wait(pid) }
-
-      mem.get_char(0).must_equal(0)
-    end
-
-    it 'protects access to a shared variable with synchronize' do
-      mutex = Mutex.new
-      mem = SharedMemory.new(:char)
-      mem.put_char(0, 0)
-
-      pids = []
-      10.times do |i|
-        inc = (-1) ** i         # half the procs increment; half decrement
-        pids << fork do
-          10.times do
-            mutex.synchronize do
-              mem.put_char(0, mem.get_char(0) + inc)
-              sleep 0.001
-            end
-          end
-          Kernel.exit!
-        end
-      end
-
-      pids.each { |pid| ::Process.wait(pid) }
-
-      mem.get_char(0).must_equal(0)
+    before :each do
+      @lock = Mutex.new
     end
     
     it 'raises exception when unlocked by other process' do
-      mutex = Mutex.new
-
       pid = Kernel.fork do
-        mutex.lock
+        @lock.lock
         sleep 0.2
-        mutex.unlock
+        @lock.unlock
         Kernel.exit!
       end
 
       sleep 0.1
-      proc { mutex.unlock }.must_raise(ProcessError)
+      proc { @lock.unlock }.must_raise(ProcessError)
 
       ::Process.wait(pid)
     end
 
     it 'raises exception when locked twice by same process' do
-      mutex = Mutex.new
-
-      mutex.lock
-      proc { mutex.lock }.must_raise(ProcessError)
-      mutex.unlock
+      @lock.lock
+      proc { @lock.lock }.must_raise(ProcessError)
+      @lock.unlock
     end
   end
 end