Fix spec to check retval instead of stdout

stdout check is fine for untidy module, since it needs messages.

spec/tools/dev/msftidy_spec.rb

@@ -8,11 +8,12 @@ RSpec.describe Msftidy do
     let(:msftidy) { Msftidy.new(auxiliary_tidy) }
 
     before(:each) do
-      @msftidy_stdout = get_stdout { msftidy.run_checks }
+      msftidy.run_checks
+      @msftidy_status = msftidy.status
     end
 
-    it "outputs nothing" do
-      expect(@msftidy_stdout).to be_empty
+    it "returns zero (no warnings or errors)" do
+      expect(@msftidy_status).to be_zero
     end
   end
 
@@ -38,11 +39,12 @@ RSpec.describe Msftidy do
     let(:msftidy) { Msftidy.new(payload_tidy) }
 
     before(:each) do
-      @msftidy_stdout = get_stdout { msftidy.run_checks }
+      msftidy.run_checks
+      @msftidy_status = msftidy.status
     end
 
-    it "outputs nothing" do
-      expect(@msftidy_stdout).to be_empty
+    it "returns zero (no warnings or errors)" do
+      expect(@msftidy_status).to be_zero
     end
   end
 end