String#exclude? core extension: inverse of #include?

3 files changed, 15 insertions, 1 deletions

diff --git a/activesupport/lib/active_support/core_ext/string.rb b/activesupport/lib/active_support/core_ext/string.rb
index 0365b6af1c..411ea0f016 100644
--- a/activesupport/lib/active_support/core_ext/string.rb
+++ b/activesupport/lib/active_support/core_ext/string.rb
@@ -7,4 +7,5 @@ require 'active_support/core_ext/string/access'
 require 'active_support/core_ext/string/xchar'
 require 'active_support/core_ext/string/behavior'
 require 'active_support/core_ext/string/interpolation'
-require 'active_support/core_ext/string/output_safety'
\ No newline at end of file
+require 'active_support/core_ext/string/output_safety'
+require 'active_support/core_ext/string/exclude'
diff --git a/activesupport/lib/active_support/core_ext/string/exclude.rb b/activesupport/lib/active_support/core_ext/string/exclude.rb
new file mode 100644
index 0000000000..5ca268b953
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/string/exclude.rb
@@ -0,0 +1,6 @@
+class String
+  # The inverse of String#include?. Returns true if the string does not include the other string.
+  def exclude?(string)
+    !include?(string)
+  end
+end
diff --git a/activesupport/test/core_ext/string_ext_test.rb b/activesupport/test/core_ext/string_ext_test.rb
index 6ed209f724..9a805bc010 100644
--- a/activesupport/test/core_ext/string_ext_test.rb
+++ b/activesupport/test/core_ext/string_ext_test.rb
@@ -441,3 +441,10 @@ class OutputSafetyTest < ActiveSupport::TestCase
     assert @string.html_safe?
   end
 end
+
+class StringExcludeTest < ActiveSupport::TestCase
+  test 'inverse of #include' do
+    assert_equal false, 'foo'.exclude?('o')
+    assert_equal true, 'foo'.exclude?('p')
+  end
+end