Better error messages for MemoizedInstanceVariableName cop

rubocop · Mar 3, 2018 · 900ae13 · 900ae13
1 parent 1a9b8c8
commit 900ae13
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Showing 2 changed files with 13 additions and 7 deletions.
diff --git a/lib/rubocop/cop/naming/memoized_instance_variable_name.rb b/lib/rubocop/cop/naming/memoized_instance_variable_name.rb
@@ -33,7 +33,8 @@ module Naming
       #   end
       #
       class MemoizedInstanceVariableName < Cop
-        MSG = 'Memoized variable does not match method name.'.freeze
+        MSG = 'Memoized variable `%<var>s` does not match ' \
+          'method name `%<method>s`. Use `@%<method>s` instead.'.freeze
 
         def self.node_pattern
           memo_assign = '(or_asgn $(ivasgn _) _)'
@@ -51,7 +52,12 @@ def self.node_pattern
         def on_def(node)
           (method_name, ivar_assign) = memoized?(node)
           return if matches?(method_name, ivar_assign)
-          add_offense(node, location: ivar_assign.source_range)
+          msg = format(
+            MSG,
+            var: ivar_assign.children.first.to_s,
+            method: method_name
+          )
+          add_offense(node, location: ivar_assign.source_range, message: msg)
         end
         alias on_defs on_def
 

diff --git a/spec/rubocop/cop/naming/memoized_instance_variable_name_spec.rb b/spec/rubocop/cop/naming/memoized_instance_variable_name_spec.rb
@@ -8,7 +8,7 @@
       expect_offense(<<-RUBY.strip_indent)
       def x
         @my_var ||= :foo
-        ^^^^^^^ Memoized variable does not match method name.
+        ^^^^^^^ Memoized variable `@my_var` does not match method name `x`. Use `@x` instead.
       end
       RUBY
     end
@@ -19,7 +19,7 @@ def x
       expect_offense(<<-RUBY.strip_indent)
       def self.x
         @my_var ||= :foo
-        ^^^^^^^ Memoized variable does not match method name.
+        ^^^^^^^ Memoized variable `@my_var` does not match method name `x`. Use `@x` instead.
       end
       RUBY
     end
@@ -30,7 +30,7 @@ def self.x
       expect_offense(<<-RUBY.strip_indent)
       foo = def x
         @y ||= :foo
-        ^^ Memoized variable does not match method name.
+        ^^ Memoized variable `@y` does not match method name `x`. Use `@x` instead.
       end
       RUBY
     end
@@ -41,7 +41,7 @@ def self.x
       expect_offense(<<-RUBY.strip_indent)
       def x
         @y ||= begin
-        ^^ Memoized variable does not match method name.
+        ^^ Memoized variable `@y` does not match method name `x`. Use `@x` instead.
           :foo
         end
       end
@@ -55,7 +55,7 @@ def x
         def foo
           helper_variable = something_we_need_to_calculate_foo
           @bar ||= calculate_expensive_thing(helper_variable)
-          ^^^^ Memoized variable does not match method name.
+          ^^^^ Memoized variable `@bar` does not match method name `foo`. Use `@foo` instead.
         end
       RUBY
     end