Assert on state, not something that didn't happen

Library/Homebrew/test/test_formula_validation.rb

@@ -55,22 +55,19 @@ class FormulaValidationTests < Test::Unit::TestCase
   end
 
   def test_devel_only_valid
-    assert_nothing_raised do
-      formula do
+    f = formula do
       devel do
         url "foo"
         version "1.0"
       end
     end
-    end
+
+    assert_equal "foo", f.url
   end
 
   def test_head_only_valid
-    assert_nothing_raised do
-      formula do
-        head "foo"
-      end
-    end
+    f = formula { head "foo" }
+    assert_equal "foo", f.url
   end
 
   def test_empty_formula_invalid