From dbc2714c24921e78011b1495a74d40e32e63d8c0 Mon Sep 17 00:00:00 2001
From: Koichi ITO <koic.ito@gmail.com>
Date: Mon, 26 Oct 2020 01:25:03 +0900
Subject: [PATCH] Accept method calls for `Style/MultipleComparison`

This PR accepts comparisons of multiple method calls for
`Style/MultipleComparison` to avoid unnecessary method calls.

```ruby
# also good
foo if a == b.lightweight || a == b.heavyweight
```

This change can reduce RuboCop's own disable comment.
---
 CHANGELOG.md                                       | 1 +
 config/default.yml                                 | 2 +-
 docs/modules/ROOT/pages/cops_lint.adoc             | 2 +-
 docs/modules/ROOT/pages/cops_style.adoc            | 2 ++
 lib/rubocop/cop/layout/extra_spacing.rb            | 3 +--
 lib/rubocop/cop/style/multiple_comparison.rb       | 6 ++++--
 spec/rubocop/cop/style/multiple_comparison_spec.rb | 9 +++++++++
 7 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8a2f67f9cfa..86b8fd77343 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,6 +19,7 @@
 
 * [#8920](https://github.com/rubocop-hq/rubocop/pull/8920): Remove Capybara's `save_screenshot` from `Lint/Debugger`. ([@ybiquitous][])
 * [#8919](https://github.com/rubocop-hq/rubocop/issues/8919): Require RuboCop AST to 1.0.1 or higher. ([@koic][])
+* [#8939](https://github.com/rubocop-hq/rubocop/pull/8939): Accept comparisons of multiple method calls for `Style/MultipleComparison`. ([@koic][])
 
 ## 1.0.0 (2020-10-21)
 
diff --git a/config/default.yml b/config/default.yml
index f77265b10ae..83e0d180829 100644
--- a/config/default.yml
+++ b/config/default.yml
@@ -1653,7 +1653,7 @@ Lint/MultipleComparison:
   Description: "Use `&&` operator to compare multiple values."
   Enabled: true
   VersionAdded: '0.47'
-  VersionChanged: '0.77'
+  VersionChanged: '1.1'
 
 Lint/NestedMethodDefinition:
   Description: 'Do not use nested method definitions.'
diff --git a/docs/modules/ROOT/pages/cops_lint.adoc b/docs/modules/ROOT/pages/cops_lint.adoc
index e2857c5f618..21a8f2daf68 100644
--- a/docs/modules/ROOT/pages/cops_lint.adoc
+++ b/docs/modules/ROOT/pages/cops_lint.adoc
@@ -2275,7 +2275,7 @@ named captures.
 | Yes
 | Yes
 | 0.47
-| 0.77
+| 1.1
 |===
 
 In math and Python, we can use `x < y < z` style comparison to compare
diff --git a/docs/modules/ROOT/pages/cops_style.adoc b/docs/modules/ROOT/pages/cops_style.adoc
index f28dc3807c9..792724f17b1 100644
--- a/docs/modules/ROOT/pages/cops_style.adoc
+++ b/docs/modules/ROOT/pages/cops_style.adoc
@@ -6017,6 +6017,7 @@ end
 
 This cop checks against comparing a variable with multiple items, where
 `Array#include?` could be used instead to avoid code repetition.
+It accepts comparisons of multiple method calls to avoid unnecessary method calls.
 
 === Examples
 
@@ -6029,6 +6030,7 @@ foo if a == 'a' || a == 'b' || a == 'c'
 # good
 a = 'a'
 foo if ['a', 'b', 'c'].include?(a)
+foo if a == b.lightweight || a == b.heavyweight
 ----
 
 == Style/MutableConstant
diff --git a/lib/rubocop/cop/layout/extra_spacing.rb b/lib/rubocop/cop/layout/extra_spacing.rb
index b6d0a0fc16a..8ac6a702b99 100644
--- a/lib/rubocop/cop/layout/extra_spacing.rb
+++ b/lib/rubocop/cop/layout/extra_spacing.rb
@@ -56,8 +56,7 @@ def aligned_locations(locs)
           aligned = Set[locs.first.line, locs.last.line]
           locs.each_cons(3) do |before, loc, after|
             col = loc.column
-            aligned << loc.line if col == before.column || # rubocop:disable Style/MultipleComparison
-                                   col == after.column
+            aligned << loc.line if col == before.column || col == after.column
           end
           aligned
         end
diff --git a/lib/rubocop/cop/style/multiple_comparison.rb b/lib/rubocop/cop/style/multiple_comparison.rb
index f1af84551d1..fd5e839960a 100644
--- a/lib/rubocop/cop/style/multiple_comparison.rb
+++ b/lib/rubocop/cop/style/multiple_comparison.rb
@@ -5,6 +5,7 @@ module Cop
     module Style
       # This cop checks against comparing a variable with multiple items, where
       # `Array#include?` could be used instead to avoid code repetition.
+      # It accepts comparisons of multiple method calls to avoid unnecessary method calls.
       #
       # @example
       #   # bad
@@ -14,6 +15,7 @@ module Style
       #   # good
       #   a = 'a'
       #   foo if ['a', 'b', 'c'].include?(a)
+      #   foo if a == b.lightweight || a == b.heavyweight
       class MultipleComparison < Base
         MSG = 'Avoid comparing a variable with multiple items ' \
           'in a conditional, use `Array#include?` instead.'
@@ -31,8 +33,8 @@ def on_or(node)
 
         def_node_matcher :simple_double_comparison?, '(send $lvar :== $lvar)'
         def_node_matcher :simple_comparison?, <<~PATTERN
-          {(send $lvar :== _)
-           (send _ :== $lvar)}
+          {(send $lvar :== !send)
+           (send !send :== $lvar)}
         PATTERN
 
         def nested_variable_comparison?(node)
diff --git a/spec/rubocop/cop/style/multiple_comparison_spec.rb b/spec/rubocop/cop/style/multiple_comparison_spec.rb
index 612a2fd3b10..77158b55355 100644
--- a/spec/rubocop/cop/style/multiple_comparison_spec.rb
+++ b/spec/rubocop/cop/style/multiple_comparison_spec.rb
@@ -66,6 +66,15 @@ def foo(x)
     RUBY
   end
 
+  it 'does not register an offense and corrects when using multiple method calls' do
+    expect_no_offenses(<<~RUBY)
+      col = loc.column
+      if col == before.column || col == after.column
+        do_something
+      end
+    RUBY
+  end
+
   it 'does not register an offense for comparing multiple literal strings' do
     expect_no_offenses(<<~RUBY)
       if "a" == "a" || "a" == "c"