From a6bc6074d6a4ad0ee50c58aeff2b2ec3b3479e97 Mon Sep 17 00:00:00 2001
From: Koichi ITO <koic.ito@gmail.com>
Date: Wed, 20 Jul 2022 11:20:45 +0900
Subject: [PATCH] Make `Lint/DeprecatedClassMethods` aware of `ENV.clone` and
 `ENV.dup`

Follow up https://github.com/ruby/ruby/pull/4557.

This PR makes `Lint/DeprecatedClassMethods` aware of `ENV.clone` and `ENV.dup`.
This update is based on the following behaviors:

```console
% ruby -v
ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-darwin19]

% ruby -we 'ENV.clone'
-e:1: warning: ENV.clone is deprecated; use ENV.to_h instead

% ruby -e 'ENV.dup'
-e:1:in `dup': Cannot dup ENV, use ENV.to_h to get a copy of ENV as a hash (TypeError)
        from -e:1:in `<main>'
```
---
 ...lass_methods_aware_of_env_clone_and_dup.md |  1 +
 .../cop/lint/deprecated_class_methods.rb      | 14 +++++---
 .../cop/lint/deprecated_class_methods_spec.rb | 34 +++++++++++++++++++
 3 files changed, 45 insertions(+), 4 deletions(-)
 create mode 100644 changelog/fix_make_lint_deprecated_class_methods_aware_of_env_clone_and_dup.md

diff --git a/changelog/fix_make_lint_deprecated_class_methods_aware_of_env_clone_and_dup.md b/changelog/fix_make_lint_deprecated_class_methods_aware_of_env_clone_and_dup.md
new file mode 100644
index 00000000000..e9514059b64
--- /dev/null
+++ b/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][])
diff --git a/lib/rubocop/cop/lint/deprecated_class_methods.rb b/lib/rubocop/cop/lint/deprecated_class_methods.rb
index 4b48bc06bbd..e87c11df60f 100644
--- a/lib/rubocop/cop/lint/deprecated_class_methods.rb
+++ b/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),
 
diff --git a/spec/rubocop/cop/lint/deprecated_class_methods_spec.rb b/spec/rubocop/cop/lint/deprecated_class_methods_spec.rb
index 654b8471eff..fe8621823b8 100644
--- a/spec/rubocop/cop/lint/deprecated_class_methods_spec.rb
+++ b/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)