test rebuilding when a source file changes

spec/build_tests_spec.rb

@@ -15,9 +15,13 @@ describe Rscons do
     FileUtils.rm_rf('build_test')
   end
 
+  def clear_cache
+    Rscons::Cache.open.clear
+  end
+
   before do
     $stdout.stub(:puts) { nil }
-    Rscons::Cache.open.clear
+    clear_cache
   end
 
   ###########################################################################
@@ -53,4 +57,19 @@ describe Rscons do
       env.Program('simple', 'simple.c')
     end
   end
+
+  it 'rebuilds the application when the source file changes' do
+    setup_testdir(['simple.c']) do
+      env = Rscons::Environment.new
+      env.Program('simple', 'simple.c')
+      `./simple`.should =~ /This is a simple C program/
+      c = File.read('simple.c')
+      File.open('simple.c', 'w') do |fh|
+        fh.puts c.sub('simple', 'modified')
+      end
+      clear_cache
+      env.Program('simple', 'simple.c')
+      `./simple`.should =~ /This is a modified C program/
+    end
+  end
 end