Start with a failing command line spec.

spec/command_line/order_spec.rb

@@ -0,0 +1,30 @@
+require 'spec_helper'
+
+describe 'command line' do
+  describe '--order' do
+    context 'given "random"' do
+      before do
+        write_file 'spec/sample_spec.rb', %Q|
+          describe 'example' do
+            specify('one') { fail }
+            specify('two') { fail }
+          end
+        |
+      end
+
+      let(:first_failures) do
+        5.times.map do
+          run_simple 'rspec spec --order random', false
+          all_output =~ /1\) example (one|two)/
+          $&
+        end
+      end
+
+      it 'runs the examples in random order' do
+        first_failures.uniq.should =~ [
+          '1 ) example one', '1 ) example two'
+        ]
+      end
+    end
+  end
+end