From a47cf48d543c75e48c9a62d97acdbe9337e1aa1d Mon Sep 17 00:00:00 2001
From: Jon Rowe <hello@jonrowe.co.uk>
Date: Wed, 28 Apr 2021 13:04:13 +0100
Subject: [PATCH] [core] Merge pull request rspec/rspec-core#2886 from
 Liberatys/extend-reserved-memoized-helper-names

Extend reserved name check

---
This commit was imported from https://github.com/rspec/rspec-core/commit/6f8ee750a4d2b24c6d4d07cbd88632542c74b06b.
---
 rspec-core/Changelog.md                       |  1 +
 rspec-core/lib/rspec/core/memoized_helpers.rb | 10 +++++---
 .../spec/rspec/core/memoized_helpers_spec.rb  | 24 ++++++++++++++++---
 3 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/rspec-core/Changelog.md b/rspec-core/Changelog.md
index c9fcf103b..078053325 100644
--- a/rspec-core/Changelog.md
+++ b/rspec-core/Changelog.md
@@ -38,6 +38,7 @@ Enhancements:
 
 * Improve pluralisation of words ending with `s` (like process). (Joshua Pinter, #2779)
 * Add ordering by file modification time (most recent first). (Matheus Richard, #2778)
+* Extend reserved memoized helper name checking for #let and #subject. (Nick Flückiger, #2886)
 
 Bug fixes:
 
diff --git a/rspec-core/lib/rspec/core/memoized_helpers.rb b/rspec-core/lib/rspec/core/memoized_helpers.rb
index 6c2389457..efa62b6e3 100644
--- a/rspec-core/lib/rspec/core/memoized_helpers.rb
+++ b/rspec-core/lib/rspec/core/memoized_helpers.rb
@@ -236,9 +236,13 @@ def let(name, &block)
           # We have to pass the block directly to `define_method` to
           # allow it to use method constructs like `super` and `return`.
           raise "#let or #subject called without a block" if block.nil?
-          raise(
-            "#let or #subject called with a reserved name #initialize"
-          ) if :initialize == name
+
+          # A list of reserved words that can't be used as a name for a memoized helper
+          # Matches for both symbols and passed strings
+          if [:initialize, :to_s].include?(name.to_sym)
+            raise ArgumentError, "#let or #subject called with reserved name `#{name}`"
+          end
+
           our_module = MemoizedHelpers.module_for(self)
 
           # If we have a module clash in our helper module
diff --git a/rspec-core/spec/rspec/core/memoized_helpers_spec.rb b/rspec-core/spec/rspec/core/memoized_helpers_spec.rb
index 30868e777..c58c5a1f8 100644
--- a/rspec-core/spec/rspec/core/memoized_helpers_spec.rb
+++ b/rspec-core/spec/rspec/core/memoized_helpers_spec.rb
@@ -520,10 +520,28 @@ def count
       end.to raise_error(/#let or #subject called without a block/)
     end
 
-    it 'raises an error when attempting to define a reserved method name' do
+    it 'raises an error when attempting to define a reserved name #initialize' do
       expect do
-        RSpec.describe { let(:initialize) { true }}
-      end.to raise_error(/#let or #subject called with a reserved name #initialize/)
+        RSpec.describe { let(:initialize) { true } }
+      end.to raise_error(/#let or #subject called with reserved name `initialize`/)
+    end
+
+    it 'raises an error when attempting to define a reserved name #initialize as a string' do
+      expect do
+        RSpec.describe { let('initialize') { true } }
+      end.to raise_error(/#let or #subject called with reserved name `initialize`/)
+    end
+
+    it 'raises an error when attempting to define a reserved name #to_s' do
+      expect do
+        RSpec.describe { let(:to_s) { true } }
+      end.to raise_error(/#let or #subject called with reserved name `to_s`/)
+    end
+
+    it 'raises an error when attempting to define a reserved name #to_s as a string' do
+      expect do
+        RSpec.describe { let('to_s') { true } }
+      end.to raise_error(/#let or #subject called with reserved name `to_s`/)
     end
 
     let(:a_value) { "a string" }