Added prefix address when IPAddr of CIDR encoded with JSON

Use `IPAddr#as_json` from the IPAddr gem if the version is 1.2.7 or higher.

Co-authored-by: Yasuo Honda <[email protected]>

Author: taketo1113

activesupport/CHANGELOG.md

@@ -1,2 +1,17 @@
+*   `ActiveSupport::JSON.encode` supports CIDR notation.
+
+    Previously:
+
+    ```ruby
+    ActiveSupport::JSON.encode(IPAddr.new("172.16.0.0/24")) # => "\"172.16.0.0\""
+    ```
+
+    After this change:
+
+    ```ruby
+    ActiveSupport::JSON.encode(IPAddr.new("172.16.0.0/24")) # => "\"172.16.0.0/24\""
+    ```
+
+    *Taketo Takashima*
 
 Please check [8-0-stable](https://github.com/rails/rails/blob/8-0-stable/activesupport/CHANGELOG.md) for previous changes.

activesupport/lib/active_support/core_ext/object/json.rb

@@ -239,9 +239,18 @@ def as_json(options = nil)
   end
 end
 
-class IPAddr # :nodoc:
-  def as_json(options = nil)
-    to_s
+unless IPAddr.method_defined?(:as_json, false)
+  # Use `IPAddr#as_json` from the IPAddr gem if the version is 1.2.7 or higher.
+  class IPAddr # :nodoc:
+    def as_json(options = nil)
+      if ipv4? && prefix == 32
+        to_s
+      elsif ipv6? && prefix == 128
+        to_s
+      else
+        "#{self}/#{prefix}"
+      end
+    end
   end
 end
 

activesupport/test/json/encoding_test_cases.rb

@@ -113,7 +113,9 @@ module EncodingTestCases
 
     PathnameTests = [[ Pathname.new("lib/index.rb"), %("lib/index.rb") ]]
 
-    IPAddrTests   = [[  IPAddr.new("127.0.0.1"), %("127.0.0.1") ]]
+    IPAddrTests       = [[ IPAddr.new("127.0.0.1"), %("127.0.0.1") ]]
+    IPAddrv4CidrTests = [[ IPAddr.new("192.0.2.0/24"), %("192.0.2.0/24") ]]
+    IPAddrv6CidrTests = [[ IPAddr.new("2001:db8::/48"), %("2001:db8::/48") ]]
 
     DateTests     = [[ Date.new(2005, 2, 1), %("2005/02/01") ]]
     TimeTests     = [[ Time.utc(2005, 2, 1, 15, 15, 10), %("2005/02/01 15:15:10 +0000") ]]