[Fix rubocop#4106] Make Style/TernaryParentheses unsafe autocorrect…

… detector smarter

This cop, despite checking for unsafe autocorrects, did not recognize
methods sent to constants or literals, leading to inappropriate omission
recommendations.

This change fixes that.

CHANGELOG.md

@@ -21,6 +21,7 @@
 * [#4152](https://github.com/bbatsov/rubocop/pull/4152): Make `Style/MethodCallWithArgsParentheses` not require parens on setter methods. ([@drenmi][])
 * [#4226](https://github.com/bbatsov/rubocop/pull/4226): Show in `--help` output that `--stdin` takes a file name argument. ([@jonas054][])
 * [#4217](https://github.com/bbatsov/rubocop/pull/4217): Fix false positive in `Rails/FilePath` cop with non string argument. ([@soutaro][])
+* [#4106](https://github.com/bbatsov/rubocop/pull/4106): Make `Style/TernaryParentheses` unsafe autocorrect detector aware of literals and constants. ([@drenmi][])
 
 ## 0.48.0 (2017-03-26)
 

lib/rubocop/cop/style/ternary_parentheses.rb

@@ -5,7 +5,8 @@ module Cop
     module Style
       # This cop checks for the presence of parentheses around ternary
       # conditions. It is configurable to enforce inclusion or omission of
-      # parentheses using `EnforcedStyle`.
+      # parentheses using `EnforcedStyle`. Omission is only enforced when
+      # removing the parentheses won't cause a different behaviour.
       #
       # @example
       #
@@ -161,7 +162,7 @@ def unparenthesized_method_call?(child)
 
         def_node_matcher :method_call_argument, <<-PATTERN
           {(:defined? $...)
-           (send {(send ...) nil} _ $(send nil _)...)}
+           (send {_ nil} _ $(send nil _)...)}
         PATTERN
 
         def_node_matcher :square_brackets?,

manual/cops_style.md

@@ -5639,7 +5639,8 @@ Enabled | Yes
 
 This cop checks for the presence of parentheses around ternary
 conditions. It is configurable to enforce inclusion or omission of
-parentheses using `EnforcedStyle`.
+parentheses using `EnforcedStyle`. Omission is only enforced when
+removing the parentheses won't cause a different behaviour.
 
 ### Example
 

spec/rubocop/cop/style/ternary_parentheses_spec.rb

@@ -198,6 +198,16 @@
                         'foo = (baz.foo? bar) ? a : b'
       end
 
+      context 'when calling method on a literal receiver' do
+        it_behaves_like 'code with offense',
+                        'foo = ("bar".foo? bar) ? a : b'
+      end
+
+      context 'when calling method on a constant receiver' do
+        it_behaves_like 'code with offense',
+                        'foo = (Bar.foo? bar) ? a : b'
+      end
+
       context 'when calling method with multiple arguments' do
         it_behaves_like 'code with offense',
                         'foo = (baz.foo? bar, baz) ? a : b'