Make Lint/DeprecatedClassMethods aware of ENV.clone and ENV.dup

changelog/fix_make_lint_deprecated_class_methods_aware_of_env_clone_and_dup.md

@@ -0,0 +1 @@
+* [#10824](https://github.com/rubocop/rubocop/pull/10824): Make `Lint/DeprecatedClassMethods` aware of `ENV.clone` and `ENV.dup`. ([@koic][])

lib/rubocop/cop/lint/deprecated_class_methods.rb

@@ -8,22 +8,22 @@ module Lint
       # @example
       #
       #   # bad
-      #
       #   File.exists?(some_path)
       #   Dir.exists?(some_path)
       #   iterator?
       #   ENV.freeze # Calling `Env.freeze` raises `TypeError` since Ruby 2.7.
+      #   ENV.clone
+      #   ENV.dup # Calling `Env.dup` raises `TypeError` since Ruby 3.1.
       #   Socket.gethostbyname(host)
       #   Socket.gethostbyaddr(host)
       #
-      # @example
-      #
       #   # good
-      #
       #   File.exist?(some_path)
       #   Dir.exist?(some_path)
       #   block_given?
       #   ENV # `ENV.freeze` cannot prohibit changes to environment variables.
+      #   ENV.to_h
+      #   ENV.to_h # `ENV.dup` cannot dup `ENV`, use `ENV.to_h` to get a copy of `ENV` as a hash.
       #   Addrinfo.getaddrinfo(nodename, service)
       #   Addrinfo.tcp(host, port).getnameinfo
       class DeprecatedClassMethods < Base
@@ -111,6 +111,12 @@ def instance_method?
           DeprecatedClassMethod.new(:freeze, class_constant: :ENV) =>
             Replacement.new(nil, class_constant: :ENV),
 
+          DeprecatedClassMethod.new(:clone, class_constant: :ENV) =>
+            Replacement.new(:to_h, class_constant: :ENV),
+
+          DeprecatedClassMethod.new(:dup, class_constant: :ENV) =>
+            Replacement.new(:to_h, class_constant: :ENV),
+
           DeprecatedClassMethod.new(:gethostbyaddr, class_constant: :Socket, correctable: false) =>
             Replacement.new(:getnameinfo, class_constant: :Addrinfo, instance_method: true),
 

spec/rubocop/cop/lint/deprecated_class_methods_spec.rb

@@ -99,6 +99,40 @@
     end
   end
 
+  context 'when using `ENV.clone`' do
+    it 'registers an offense' do
+      expect_offense(<<~RUBY)
+        ENV.clone
+            ^^^^^ `ENV.clone` is deprecated in favor of `ENV.to_h`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        ENV.to_h
+      RUBY
+    end
+
+    it 'does not register an offense for method calls to `ENV` other than `clone`' do
+      expect_no_offenses('ENV.values')
+    end
+  end
+
+  context 'when using `ENV.dup`' do
+    it 'registers an offense' do
+      expect_offense(<<~RUBY)
+        ENV.dup
+            ^^^ `ENV.dup` is deprecated in favor of `ENV.to_h`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        ENV.to_h
+      RUBY
+    end
+
+    it 'does not register an offense for method calls to `ENV` other than `dup`' do
+      expect_no_offenses('ENV.values')
+    end
+  end
+
   context 'prefer `Addrinfo#getnameinfo` over `Socket.gethostbyaddr`' do
     it 'registers an offense for Socket.gethostbyaddr' do
       expect_offense(<<~RUBY)