Fix subject name in HasExecutable specs

spec/producer/core/tests/has_executable_spec.rb

@@ -3,7 +3,7 @@ require 'spec_helper'
 module Producer::Core
   module Tests
     describe HasExecutable, :env do
-      subject(:has_env) { HasExecutable.new(env, executable) }
+      subject(:test) { HasExecutable.new(env, executable) }
 
       it_behaves_like 'test'
 
@@ -12,7 +12,7 @@ module Producer::Core
           let(:executable) { 'true' }
 
           it 'returns true' do
-            expect(has_env.verify).to be true
+            expect(test.verify).to be true
           end
         end
 
@@ -20,7 +20,7 @@ module Producer::Core
           let(:executable) { 'some_non_existent_executable' }
 
           it 'returns false' do
-            expect(has_env.verify).to be false
+            expect(test.verify).to be false
           end
         end
       end