One-liner for switching over to using "double" instead of "stub" to create test double, the latter of which is deprecated in RSpec 3. This should not touch actual stubbing (e.g. something.stub(awesome: true)), or stubbing of constants for example (e.g., stub_const "MyArray"...)

_undeprecate.sh

find spec -name '*.rb' | xargs sed -i '' -E 's/([^.]|^)stub([^_]|$)/\1double\2/g'

sample.rb.diff

diff --git a/spec/sample.rb b/spec/sample.rb
index 72fb490..5eed42f 100644
--- a/spec/sample.rb
+++ b/spec/sample.rb
@@ -1,4 +1,4 @@
-my_object  = stub
-my_objects = [stub, stub]
+my_object  = double
+my_objects = [double, double]
 some_real_object.stub :saved => true
 stub_const "MyClass"