Merge pull request #134 from fatkodima/support-function-calls-in-size…

…_cop

Support `Array()` and `Hash()` methods for `Performance/Size` cop

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### New features
 
+* [#125](https://github.com/rubocop-hq/rubocop-performance/pull/125): Support `Array()` and `Hash()` methods for `Performance/Size` cop. ([@fatkodima][])
 * [#124](https://github.com/rubocop-hq/rubocop-performance/pull/124): Add new `Performance/Squeeze` cop. ([@fatkodima][])
 * [#129](https://github.com/rubocop-hq/rubocop-performance/pull/129): Add new `Performance/BigDecimalWithNumericArgument` cop. ([@fatkodima][])
 * [#130](https://github.com/rubocop-hq/rubocop-performance/pull/130): Add new `Performance/SortReverse` cop. ([@fatkodima][])

docs/modules/ROOT/pages/cops_performance.adoc

@@ -1179,15 +1179,27 @@ have been assigned to an array or a hash.
 ----
 # bad
 [1, 2, 3].count
+(1..3).to_a.count
+Array[*1..3].count
+Array(1..3).count
 
 # bad
 {a: 1, b: 2, c: 3}.count
+[[:foo, :bar], [1, 2]].to_h.count
+Hash[*('a'..'z')].count
+Hash(key: :value).count
 
 # good
 [1, 2, 3].size
+(1..3).to_a.size
+Array[*1..3].size
+Array(1..3).size
 
 # good
 {a: 1, b: 2, c: 3}.size
+[[:foo, :bar], [1, 2]].to_h.size
+Hash[*('a'..'z')].size
+Hash(key: :value).size
 
 # good
 [1, 2, 3].count { |e| e > 2 }

lib/rubocop/cop/performance/size.rb

@@ -9,15 +9,27 @@ module Performance
       # @example
       #   # bad
       #   [1, 2, 3].count
+      #   (1..3).to_a.count
+      #   Array[*1..3].count
+      #   Array(1..3).count
       #
       #   # bad
       #   {a: 1, b: 2, c: 3}.count
+      #   [[:foo, :bar], [1, 2]].to_h.count
+      #   Hash[*('a'..'z')].count
+      #   Hash(key: :value).count
       #
       #   # good
       #   [1, 2, 3].size
+      #   (1..3).to_a.size
+      #   Array[*1..3].size
+      #   Array(1..3).size
       #
       #   # good
       #   {a: 1, b: 2, c: 3}.size
+      #   [[:foo, :bar], [1, 2]].to_h.size
+      #   Hash[*('a'..'z')].size
+      #   Hash(key: :value).size
       #
       #   # good
       #   [1, 2, 3].count { |e| e > 2 }
@@ -31,6 +43,7 @@ class Size < Cop
             [!nil? array_type?]
             (send _ :to_a)
             (send (const nil? :Array) :[] _)
+            (send nil? :Array _)
           }
         PATTERN
 
@@ -39,6 +52,7 @@ class Size < Cop
             [!nil? hash_type?]
             (send _ :to_h)
             (send (const nil? :Hash) :[] _)
+            (send nil? :Hash _)
           }
         PATTERN
 

spec/rubocop/cop/performance/size_spec.rb

@@ -35,6 +35,13 @@
       RUBY
     end
 
+    it 'registers an offense when calling count on Array()' do
+      expect_offense(<<~RUBY)
+        Array(1..5).count
+                    ^^^^^ Use `size` instead of `count`.
+      RUBY
+    end
+
     it 'does not register an offense when calling size' do
       expect_no_offenses('[1, 2, 3].size')
     end
@@ -72,6 +79,12 @@
 
       expect(new_source).to eq('Array[*1..5].size')
     end
+
+    it 'corrects count to size on Array()' do
+      new_source = autocorrect_source('Array(1..5).count')
+
+      expect(new_source).to eq('Array(1..5).size')
+    end
   end
 
   describe 'on hash' do
@@ -96,6 +109,13 @@
       RUBY
     end
 
+    it 'registers an offense when calling count on Hash()' do
+      expect_offense(<<~RUBY)
+        Hash(key: :value).count
+                          ^^^^^ Use `size` instead of `count`.
+      RUBY
+    end
+
     it 'does not register an offense when calling size' do
       expect_no_offenses('{a: 1, b: 2, c: 3}.size')
     end
@@ -133,5 +153,11 @@
 
       expect(new_source).to eq("Hash[*('a'..'z')].size")
     end
+
+    it 'corrects count to size on Hash()' do
+      new_source = autocorrect_source('Hash(key: :value).count')
+
+      expect(new_source).to eq('Hash(key: :value).size')
+    end
   end
 end