Pass symbol as an argument to build instead of a block

spec/blackhole_spec.rb

@@ -3,9 +3,7 @@
 describe 'black hole null object' do
   subject(:null) { null_class.new }
   let(:null_class) do
-    Naught.build do |b|
-      b.black_hole
-    end
+    Naught.build(&:black_hole)
   end
 
   it 'returns self from arbitray method calls' do

spec/explicit_conversions_spec.rb

@@ -2,9 +2,7 @@
 
 describe 'explicitly convertable null object' do
   let(:null_class) do
-    Naught.build do |b|
-      b.define_explicit_conversions
-    end
+    Naught.build(&:define_explicit_conversions)
   end
   subject(:null) { null_class.new }
 

spec/implicit_conversions_spec.rb

@@ -3,9 +3,7 @@
 describe 'implicitly convertable null object' do
   subject(:null) { null_class.new }
   let(:null_class) do
-    Naught.build do |b|
-      b.define_implicit_conversions
-    end
+    Naught.build(&:define_implicit_conversions)
   end
   it 'implicitly splats the same way an empty array does' do
     a, b = null

spec/naught_spec.rb

@@ -42,9 +42,7 @@ def y
   end
   let(:instantiation_line) { null_object_and_line.last }
   let(:trace_null_class) do
-    Naught.build do |b|
-      b.traceable
-    end
+    Naught.build(&:traceable)
   end
 
   it 'remembers the file it was instantiated from' do

spec/singleton_null_object_spec.rb

@@ -2,9 +2,7 @@
 
 describe 'singleton null object' do
   subject(:null_class) do
-    Naught.build do |b|
-      b.singleton
-    end
+    Naught.build(&:singleton)
   end
 
   it 'does not respond to .new' do