test short echo mode

spec/build_tests_spec.rb

@@ -33,6 +33,17 @@ describe Rscons do
     end
   end
 
+  it 'supports short echo mode' do
+    $stdout.should_receive(:puts).once.with('CC simple.o')
+    $stdout.should_receive(:puts).once.with('LD simple')
+    setup_testdir(['simple.c']) do
+      env = Rscons::Environment.new(echo: :short)
+      env.Program('simple', 'simple.c')
+      File.exist?('simple.o').should be_true
+      `./simple`.should =~ /This is a simple C program/
+    end
+  end
+
   it 'does not rebuild the program if no sources changed' do
     $stdout.should_receive(:puts).once.with('gcc -c -o simple.o simple.c')
     $stdout.should_receive(:puts).once.with('gcc -o simple simple.o')