diff --git a/spec/builtin_contracts_spec.rb b/spec/builtin_contracts_spec.rb
index c3580cd..be718ad 100644
--- a/spec/builtin_contracts_spec.rb
+++ b/spec/builtin_contracts_spec.rb
@@ -3,296 +3,304 @@
     @o = GenericExample.new
   end
 
+  def fails(&some)
+    expect { some.call }.to raise_error(ContractError)
+  end
+
+  def passes(&some)
+    expect { some.call }.to_not raise_error
+  end
+
   describe "DescendantOf:" do
     it "should pass for Array" do
-      expect { @o.enumerable_descendant_test(Array) }.to_not raise_error
+      passes { @o.enumerable_descendant_test(Array) }
     end
 
     it "should pass for a hash" do
-      expect { @o.enumerable_descendant_test(Hash) }.to_not raise_error
+      passes { @o.enumerable_descendant_test(Hash) }
     end
 
     it "should fail for a number class" do
-      expect { @o.enumerable_descendant_test(Integer) }.to raise_error(ContractError)
+      fails { @o.enumerable_descendant_test(Integer) }
     end
 
     it "should fail for a non-class" do
-      expect { @o.enumerable_descendant_test(1) }.to raise_error(ContractError)
+      fails { @o.enumerable_descendant_test(1) }
     end
   end
 
   describe "Num:" do
     it "should pass for Fixnums" do
-      expect { @o.double(2) }.to_not raise_error
+      passes { @o.double(2) }
     end
 
     it "should pass for Floats" do
-      expect { @o.double(2.2) }.to_not raise_error
+      passes { @o.double(2.2) }
     end
 
     it "should fail for nil and other data types" do
-      expect { @o.double(nil) }.to raise_error(ContractError)
-      expect { @o.double(:x)  }.to raise_error(ContractError)
-      expect { @o.double("x") }.to raise_error(ContractError)
-      expect { @o.double(/x/) }.to raise_error(ContractError)
+      fails { @o.double(nil) }
+      fails { @o.double(:x) }
+      fails { @o.double("x") }
+      fails { @o.double(/x/) }
     end
   end
 
   describe "Pos:" do
     it "should pass for positive numbers" do
-      expect { @o.pos_test(1) }.to_not raise_error
-      expect { @o.pos_test(1.6) }.to_not raise_error
+      passes { @o.pos_test(1) }
+      passes { @o.pos_test(1.6) }
     end
 
     it "should fail for 0" do
-      expect { @o.pos_test(0) }.to raise_error(ContractError)
+      fails { @o.pos_test(0) }
     end
 
     it "should fail for negative numbers" do
-      expect { @o.pos_test(-1) }.to raise_error(ContractError)
-      expect { @o.pos_test(-1.6) }.to raise_error(ContractError)
+      fails { @o.pos_test(-1) }
+      fails { @o.pos_test(-1.6) }
     end
 
     it "should fail for nil and other data types" do
-      expect { @o.pos_test(nil) }.to raise_error(ContractError)
-      expect { @o.pos_test(:x)  }.to raise_error(ContractError)
-      expect { @o.pos_test("x") }.to raise_error(ContractError)
-      expect { @o.pos_test(/x/) }.to raise_error(ContractError)
+      fails { @o.pos_test(nil) }
+      fails { @o.pos_test(:x)  }
+      fails { @o.pos_test("x") }
+      fails { @o.pos_test(/x/) }
     end
   end
 
   describe "Neg:" do
     it "should pass for negative numbers" do
-      expect { @o.neg_test(-1) }.to_not raise_error
-      expect { @o.neg_test(-1.6) }.to_not raise_error
+      passes { @o.neg_test(-1) }
+      passes { @o.neg_test(-1.6) }
     end
 
     it "should fail for 0" do
-      expect { @o.neg_test(0) }.to raise_error(ContractError)
+      fails { @o.neg_test(0) }
     end
 
     it "should fail for positive numbers" do
-      expect { @o.neg_test(1) }.to raise_error(ContractError)
-      expect { @o.neg_test(1.6) }.to raise_error(ContractError)
+      fails { @o.neg_test(1) }
+      fails { @o.neg_test(1.6) }
     end
 
     it "should fail for nil and other data types" do
-      expect { @o.neg_test(nil) }.to raise_error(ContractError)
-      expect { @o.neg_test(:x)  }.to raise_error(ContractError)
-      expect { @o.neg_test("x") }.to raise_error(ContractError)
-      expect { @o.neg_test(/x/) }.to raise_error(ContractError)
+      fails { @o.neg_test(nil) }
+      fails { @o.neg_test(:x)  }
+      fails { @o.neg_test("x") }
+      fails { @o.neg_test(/x/) }
     end
   end
 
   describe "Nat:" do
     it "should pass for 0" do
-      expect { @o.nat_test(0) }.to_not raise_error
+      passes { @o.nat_test(0) }
     end
 
     it "should pass for positive whole numbers" do
-      expect { @o.nat_test(1) }.to_not raise_error
+      passes { @o.nat_test(1) }
     end
 
     it "should fail for positive non-whole numbers" do
-      expect { @o.nat_test(1.5) }.to raise_error(ContractError)
+      fails { @o.nat_test(1.5) }
     end
 
     it "should fail for negative numbers" do
-      expect { @o.nat_test(-1) }.to raise_error(ContractError)
-      expect { @o.nat_test(-1.6) }.to raise_error(ContractError)
+      fails { @o.nat_test(-1) }
+      fails { @o.nat_test(-1.6) }
     end
 
     it "should fail for nil and other data types" do
-      expect { @o.nat_test(nil) }.to raise_error(ContractError)
-      expect { @o.nat_test(:x)  }.to raise_error(ContractError)
-      expect { @o.nat_test("x") }.to raise_error(ContractError)
-      expect { @o.nat_test(/x/) }.to raise_error(ContractError)
+      fails { @o.nat_test(nil) }
+      fails { @o.nat_test(:x)  }
+      fails { @o.nat_test("x") }
+      fails { @o.nat_test(/x/) }
     end
   end
 
   describe "Any:" do
     it "should pass for numbers" do
-      expect { @o.show(1) }.to_not raise_error
+      passes { @o.show(1) }
     end
     it "should pass for strings" do
-      expect { @o.show("bad") }.to_not raise_error
+      passes { @o.show("bad") }
     end
     it "should pass for procs" do
-      expect { @o.show(lambda {}) }.to_not raise_error
+      passes { @o.show(lambda {}) }
     end
     it "should pass for nil" do
-      expect { @o.show(nil) }.to_not raise_error
+      passes { @o.show(nil) }
     end
   end
 
   describe "None:" do
     it "should fail for numbers" do
-      expect { @o.fail_all(1) }.to raise_error(ContractError)
+      fails { @o.fail_all(1) }
     end
     it "should fail for strings" do
-      expect { @o.fail_all("bad") }.to raise_error(ContractError)
+      fails { @o.fail_all("bad") }
     end
     it "should fail for procs" do
-      expect { @o.fail_all(lambda {}) }.to raise_error(ContractError)
+      fails { @o.fail_all(lambda {}) }
     end
     it "should fail for nil" do
-      expect { @o.fail_all(nil) }.to raise_error(ContractError)
+      fails { @o.fail_all(nil) }
     end
   end
 
   describe "Or:" do
     it "should pass for nums" do
-      expect { @o.num_or_string(1) }.to_not raise_error
+      passes { @o.num_or_string(1) }
     end
 
     it "should pass for strings" do
-      expect { @o.num_or_string("bad") }.to_not raise_error
+      passes { @o.num_or_string("bad") }
     end
 
     it "should fail for nil" do
-      expect { @o.num_or_string(nil) }.to raise_error(ContractError)
+      fails { @o.num_or_string(nil) }
     end
   end
 
   describe "Xor:" do
     it "should pass for an object with a method :good" do
-      expect { @o.xor_test(A.new) }.to_not raise_error
+      passes { @o.xor_test(A.new) }
     end
 
     it "should pass for an object with a method :bad" do
-      expect { @o.xor_test(B.new) }.to_not raise_error
+      passes { @o.xor_test(B.new) }
     end
 
     it "should fail for an object with neither method" do
-      expect { @o.xor_test(1) }.to raise_error(ContractError)
+      fails { @o.xor_test(1) }
     end
 
     it "should fail for an object with both methods :good and :bad" do
-      expect { @o.xor_test(F.new) }.to raise_error(ContractError)
+      fails { @o.xor_test(F.new) }
     end
   end
 
   describe "And:" do
     it "should pass for an object of class A that has a method :good" do
-      expect { @o.and_test(A.new) }.to_not raise_error
+      passes { @o.and_test(A.new) }
     end
 
     it "should fail for an object that has a method :good but isn't of class A" do
-      expect { @o.and_test(F.new) }.to raise_error(ContractError)
+      fails { @o.and_test(F.new) }
     end
   end
 
   describe "Enum:" do
     it "should pass for an object that is included" do
-      expect { @o.enum_test(:a) }.to_not raise_error
+      passes { @o.enum_test(:a) }
     end
 
     it "should fail for an object that is not included" do
-      expect { @o.enum_test(:z) }.to raise_error(ContractError)
+      fails { @o.enum_test(:z) }
     end
   end
 
   describe "RespondTo:" do
     it "should pass for an object that responds to :good" do
-      expect { @o.responds_test(A.new) }.to_not raise_error
+      passes { @o.responds_test(A.new) }
     end
 
     it "should fail for an object that doesn't respond to :good" do
-      expect { @o.responds_test(B.new) }.to raise_error(ContractError)
+      fails { @o.responds_test(B.new) }
     end
   end
 
   describe "Send:" do
     it "should pass for an object that returns true for method :good" do
-      expect { @o.send_test(A.new) }.to_not raise_error
+      passes { @o.send_test(A.new) }
     end
 
     it "should fail for an object that returns false for method :good" do
-      expect { @o.send_test(F.new) }.to raise_error(ContractError)
+      fails { @o.send_test(F.new) }
     end
   end
 
   describe "Exactly:" do
     it "should pass for an object that is exactly a Parent" do
-      expect { @o.exactly_test(Parent.new) }.to_not raise_error
+      passes { @o.exactly_test(Parent.new) }
     end
 
     it "should fail for an object that inherits from Parent" do
-      expect { @o.exactly_test(Child.new) }.to raise_error(ContractError)
+      fails { @o.exactly_test(Child.new) }
     end
 
     it "should fail for an object that is not related to Parent at all" do
-      expect { @o.exactly_test(A.new) }.to raise_error(ContractError)
+      fails { @o.exactly_test(A.new) }
     end
   end
 
   describe "Eq:" do
     it "should pass for a class" do
-      expect { @o.eq_class_test(Foo) }
+      passes { @o.eq_class_test(Foo) }
     end
 
     it "should pass for a module" do
-      expect { @o.eq_module_test(Bar) }
+      passes { @o.eq_module_test(Bar) }
     end
 
     it "should pass for other values" do
-      expect { @o.eq_value_test(Baz) }
+      passes { @o.eq_value_test(Baz) }
     end
 
     it "should fail when not equal" do
-      expect { @o.eq_class_test(Bar) }.to raise_error(ContractError)
+      fails { @o.eq_class_test(Bar) }
     end
 
     it "should fail when given instance of class" do
-      expect { @o.eq_class_test(Foo.new) }.to raise_error(ContractError)
+      fails { @o.eq_class_test(Foo.new) }
     end
   end
 
   describe "Not:" do
     it "should pass for an argument that isn't nil" do
-      expect { @o.not_nil(1) }.to_not raise_error
+      passes { @o.not_nil(1) }
     end
 
     it "should fail for nil" do
-      expect { @o.not_nil(nil) }.to raise_error(ContractError)
+      fails { @o.not_nil(nil) }
     end
   end
 
   describe "ArrayOf:" do
     it "should pass for an array of nums" do
-      expect { @o.product([1, 2, 3]) }.to_not raise_error
+      passes { @o.product([1, 2, 3]) }
     end
 
     it "should fail for an array with one non-num" do
-      expect { @o.product([1, 2, 3, "bad"]) }.to raise_error(ContractError)
+      fails { @o.product([1, 2, 3, "bad"]) }
     end
 
     it "should fail for a non-array" do
-      expect { @o.product(1) }.to raise_error(ContractError)
+      fails { @o.product(1) }
     end
   end
 
   describe "RangeOf:" do
     require "date"
     it "should pass for a range of nums" do
-      expect { @o.first_in_range_num(3..10) }.to_not raise_error
+      passes { @o.first_in_range_num(3..10) }
     end
 
     it "should pass for a range of dates" do
       d1 = Date.today
       d2 = d1 + 18
-      expect { @o.first_in_range_date(d1..d2) }.to_not raise_error
+      passes { @o.first_in_range_date(d1..d2) }
     end
 
     it "should fail for a non-range" do
-      expect { @o.first_in_range_num("foo") }.to raise_error(ContractError)
-      expect { @o.first_in_range_num(:foo) }.to raise_error(ContractError)
-      expect { @o.first_in_range_num(5) }.to raise_error(ContractError)
-      expect { @o.first_in_range_num(nil) }.to raise_error(ContractError)
+      fails { @o.first_in_range_num("foo") }
+      fails { @o.first_in_range_num(:foo) }
+      fails { @o.first_in_range_num(5) }
+      fails { @o.first_in_range_num(nil) }
     end
 
     it "should fail for a range with incorrect data type" do
-      expect { @o.first_in_range_num("a".."z") }.to raise_error(ContractError)
+      fails { @o.first_in_range_num("a".."z") }
     end
 
     it "should fail for a badly-defined range" do
@@ -302,8 +310,8 @@
       # This test guards against ranges with inconsistent data types.
       begin
         d1 = Date.today
-        expect { @o.first_in_range_date(d1..10).to raise_error(ContractError) }
-        expect { @o.first_in_range_num(d1..10).to raise_error(ContractError) }
+        fails { @o.first_in_range_date(d1..10) }
+        fails { @o.first_in_range_num(d1..10) }
       rescue ArgumentError
         # If Ruby doesn't like the range, we ignore the test.
         :nop
@@ -313,26 +321,26 @@
 
   describe "SetOf:" do
     it "should pass for a set of nums" do
-      expect { @o.product_from_set(Set.new([1, 2, 3])) }.to_not raise_error
+      passes { @o.product_from_set(Set.new([1, 2, 3])) }
     end
 
     it "should fail for an array with one non-num" do
-      expect { @o.product_from_set(Set.new([1, 2, 3, "bad"])) }.to raise_error(ContractError)
+      fails { @o.product_from_set(Set.new([1, 2, 3, "bad"])) }
     end
 
     it "should fail for a non-array" do
-      expect { @o.product_from_set(1) }.to raise_error(ContractError)
+      fails { @o.product_from_set(1) }
     end
   end
 
   describe "Bool:" do
     it "should pass for an argument that is a boolean" do
-      expect { @o.bool_test(true) }.to_not raise_error
-      expect { @o.bool_test(false) }.to_not raise_error
+      passes { @o.bool_test(true) }
+      passes { @o.bool_test(false) }
     end
 
     it "should fail for nil" do
-      expect { @o.bool_test(nil) }.to raise_error(ContractError)
+      fails { @o.bool_test(nil) }
     end
   end
 
@@ -346,31 +354,31 @@
     end
 
     it "should fail for strings" do
-      expect { @o.maybe_double("foo") }.to raise_error(ContractError)
+      fails { @o.maybe_double("foo") }
     end
   end
 
   describe "KeywordArgs:" do
     it "should pass for exact correct input" do
-      expect { @o.person_keywordargs(:name => "calvin", :age => 10) }.to_not raise_error
+      passes { @o.person_keywordargs(:name => "calvin", :age => 10) }
     end
 
     it "should fail if some keys don't have contracts" do
-      expect { @o.person_keywordargs(:name => "calvin", :age => 10, :foo => "bar") }.to raise_error(ContractError)
+      fails { @o.person_keywordargs(:name => "calvin", :age => 10, :foo => "bar") }
     end
 
     it "should fail if a key with a contract on it isn't provided" do
-      expect { @o.person_keywordargs(:name => "calvin") }.to raise_error(ContractError)
+      fails { @o.person_keywordargs(:name => "calvin") }
     end
 
     it "should fail for incorrect input" do
-      expect { @o.person_keywordargs(:name => 50, :age => 10) }.to raise_error(ContractError)
-      expect { @o.hash_keywordargs(:hash => nil) }.to raise_error(ContractError)
-      expect { @o.hash_keywordargs(:hash => 1) }.to raise_error(ContractError)
+      fails { @o.person_keywordargs(:name => 50, :age => 10) }
+      fails { @o.hash_keywordargs(:hash => nil) }
+      fails { @o.hash_keywordargs(:hash => 1) }
     end
 
     it "should pass if a method is overloaded with non-KeywordArgs" do
-      expect { @o.person_keywordargs("name", 10) }.to_not raise_error
+      passes { @o.person_keywordargs("name", 10) }
     end
   end
 
@@ -402,10 +410,10 @@ def something(hash)
     end
 
     context "given an unfulfilled contract" do
-      it { expect { @o.gives_max_value(:panda => "1", :bamboo => "2") }.to raise_error(ContractError) }
-      it { expect { @o.gives_max_value(nil) }.to raise_error(ContractError) }
-      it { expect { @o.gives_max_value(1) }.to raise_error(ContractError) }
-      it { expect { @o.pretty_gives_max_value(:panda => "1", :bamboo => "2") }.to raise_error(ContractError) }
+      it { fails { @o.gives_max_value(:panda => "1", :bamboo => "2") }  }
+      it { fails { @o.gives_max_value(nil) } }
+      it { fails { @o.gives_max_value(1) } }
+      it { fails { @o.pretty_gives_max_value(:panda => "1", :bamboo => "2") } }
     end
 
     describe "#to_s" do
@@ -422,39 +430,31 @@ def something(hash)
   describe "StrictHash:" do
     context "when given an exact correct input" do
       it "does not raise an error" do
-        expect do
-          @o.strict_person(:name => "calvin", :age => 10)
-        end.to_not raise_error
+        passes { @o.strict_person(:name => "calvin", :age => 10) }
       end
     end
 
     context "when given an input with correct keys but wrong types" do
       it "raises an error" do
-        expect do
-          @o.strict_person(:name => "calvin", :age => "10")
-        end.to raise_error(ContractError)
+        fails { @o.strict_person(:name => "calvin", :age => "10") }
       end
     end
 
     context "when given an input with missing keys" do
       it "raises an error" do
-        expect do
-          @o.strict_person(:name => "calvin")
-        end.to raise_error(ContractError)
+        fails { @o.strict_person(:name => "calvin") }
       end
     end
 
     context "when given an input with extra keys" do
       it "raises an error" do
-        expect do
-          @o.strict_person(:name => "calvin", :age => "10", :soft => true)
-        end.to raise_error(ContractError)
+        fails { @o.strict_person(:name => "calvin", :age => "10", :soft => true) }
       end
     end
 
     context "when given not a hash" do
       it "raises an error" do
-        expect { @o.strict_person(1337) }.to raise_error(ContractError)
+        fails { @o.strict_person(1337) }
       end
     end
   end