Add autocorrection support for RSpec/IteratedExpectation for single expectations

lovro-bikic · lovro-bikic · commit 4af6191d6239 · 2025-08-03T13:49:52.000+02:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,6 +6,7 @@
 - Fix a false positive for `RSpec/LeakyConstantDeclaration` when defining constants in explicit namespaces. ([@naveg])
 - Add support for error matchers (`raise_exception` and `raise_error`) to `RSpec/Dialect`. ([@lovro-bikic])
 - Don't register offenses for `RSpec/DescribedClass` within `Data.define` blocks. ([@lovro-bikic])
+- Add autocorrection support for `RSpec/IteratedExpectation` for single expectations. ([@lovro-bikic])
 
 ## 3.6.0 (2025-04-18)
 
diff --git a/docs/modules/ROOT/pages/cops_rspec.adoc b/docs/modules/ROOT/pages/cops_rspec.adoc
@@ -3191,7 +3191,7 @@ it_should_behave_like 'a foo'
 
 | Enabled
 | Yes
-| No
+| Always
 | 1.14
 | -
 |===
diff --git a/lib/rubocop/cop/rspec/iterated_expectation.rb b/lib/rubocop/cop/rspec/iterated_expectation.rb
@@ -17,6 +17,8 @@ module RSpec
       #   end
       #
       class IteratedExpectation < Base
+        extend AutoCorrector
+
         MSG = 'Prefer using the `all` matcher instead ' \
               'of iterating over an array.'
 
@@ -25,14 +27,14 @@ class IteratedExpectation < Base
           (block
             (send ... :each)
             (args (arg $_))
-            $(...)
+            (...)
           )
         PATTERN
 
         # @!method each_numblock?(node)
         def_node_matcher :each_numblock?, <<~PATTERN
           (numblock
-            (send ... :each) _ $(...)
+            (send ... :each) _ (...)
           )
         PATTERN
 
@@ -42,23 +44,43 @@ class IteratedExpectation < Base
         PATTERN
 
         def on_block(node)
-          each?(node) do |arg, body|
-            if single_expectation?(body, arg) || only_expectations?(body, arg)
-              add_offense(node.send_node)
-            end
+          each?(node) do |arg|
+            check_offense(node, arg)
           end
         end
 
         def on_numblock(node)
-          each_numblock?(node) do |body|
-            if single_expectation?(body, :_1) || only_expectations?(body, :_1)
-              add_offense(node.send_node)
-            end
+          each_numblock?(node) do
+            check_offense(node, :_1)
           end
         end
 
         private
 
+        def check_offense(node, argument)
+          if single_expectation?(node.body, argument)
+            add_offense(node.send_node) do |corrector|
+              next unless node.body.arguments.one?
+              next if uses_argument_in_matcher?(node, argument)
+
+              corrector.replace(node, single_expectation_replacement(node))
+            end
+          elsif only_expectations?(node.body, argument)
+            add_offense(node.send_node)
+          end
+        end
+
+        def single_expectation_replacement(node)
+          collection = node.receiver.source
+          matcher = node.body.first_argument.source
+
+          "expect(#{collection}).to all(#{matcher})"
+        end
+
+        def uses_argument_in_matcher?(node, argument)
+          node.body.first_argument.each_descendant.any?(s(:lvar, argument))
+        end
+
         def single_expectation?(body, arg)
           expectation?(body, arg)
         end
diff --git a/spec/rubocop/cop/rspec/iterated_expectation_spec.rb b/spec/rubocop/cop/rspec/iterated_expectation_spec.rb
@@ -8,6 +8,12 @@
         ^^^^^^^^^^^^^^^^^^^^^^^^^^ Prefer using the `all` matcher instead of iterating over an array.
       end
     RUBY
+
+    expect_correction(<<~RUBY)
+      it 'validates users' do
+        expect([user1, user2, user3]).to all(be_valid)
+      end
+    RUBY
   end
 
   it 'flags `each` when expectation calls method with arguments' do
@@ -17,6 +23,35 @@
         ^^^^^^^^^^^^^^^^^^^^^^^^^^ Prefer using the `all` matcher instead of iterating over an array.
       end
     RUBY
+
+    expect_correction(<<~RUBY)
+      it 'validates users' do
+        expect([user1, user2, user3]).to all(be_a(User))
+      end
+    RUBY
+  end
+
+  it 'flags `each` when the expectation specifies an error message, but ' \
+     'does not correct' do
+    expect_offense(<<~RUBY)
+      it 'validates users' do
+        [user1, user2, user3].each { |user| expect(user).to be_a(User), "user is not a User" }
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^ Prefer using the `all` matcher instead of iterating over an array.
+      end
+    RUBY
+
+    expect_no_corrections
+  end
+
+  it 'flags `each` when matcher uses block argument, but does not correct' do
+    expect_offense(<<~RUBY)
+      it 'validates users' do
+        [user1, user2, user3].each { |user| expect(user).to receive(:flag).and_return(user.flag) }
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^ Prefer using the `all` matcher instead of iterating over an array.
+      end
+    RUBY
+
+    expect_no_corrections
   end
 
   it 'ignores `each` without expectation' do
@@ -45,6 +80,8 @@
         end
       end
     RUBY
+
+    expect_no_corrections
   end
 
   it 'ignore `each` when the body does not contain only expectations' do
@@ -94,6 +131,12 @@
           ^^^^^^^^^^^^^^^^^^^^^^^^^^ Prefer using the `all` matcher instead of iterating over an array.
         end
       RUBY
+
+      expect_correction(<<~RUBY)
+        it 'validates users' do
+          expect([user1, user2, user3]).to all(be_valid)
+        end
+      RUBY
     end
 
     it 'flags `each` when expectation calls method with arguments' do
@@ -103,6 +146,12 @@
           ^^^^^^^^^^^^^^^^^^^^^^^^^^ Prefer using the `all` matcher instead of iterating over an array.
         end
       RUBY
+
+      expect_correction(<<~RUBY)
+        it 'validates users' do
+          expect([user1, user2, user3]).to all(be_a(User))
+        end
+      RUBY
     end
 
     it 'ignores `each` without expectation' do
@@ -123,6 +172,8 @@
           end
         end
       RUBY
+
+      expect_no_corrections
     end
 
     it 'ignore `each` when the body does not contain only expectations' do
