Remove “join” from the list of trigger methods

spec/ameba/rule/performance/map_instead_of_block_spec.cr

@@ -6,30 +6,29 @@ module Ameba::Rule::Performance
   describe MapInsteadOfBlock do
     it "passes if there is no potential performance improvements" do
       source = Source.new %(
-        (1..3).join(&.to_s)
         (1..3).sum(&.*(2))
         (1..3).product(&.*(2))
       )
       subject.catch(source).should be_valid
     end
 
-    it "reports if there is map followed by join without a block" do
+    it "reports if there is map followed by sum without a block" do
       source = Source.new %(
-        (1..3).map(&.to_s).join
+        (1..3).map(&.to_u64).sum
       )
       subject.catch(source).should_not be_valid
     end
 
-    it "reports if there is map followed by join without a block (with argument)" do
+    it "reports if there is map followed by sum without a block (with argument)" do
       source = Source.new %(
-        (1..3).map(&.to_s).join('.')
+        (1..3).map(&.to_u64).sum(0)
       )
       subject.catch(source).should_not be_valid
     end
 
-    it "reports if there is map followed by join with a block" do
+    it "reports if there is map followed by sum with a block" do
       source = Source.new %(
-        (1..3).map(&.to_s).join(&.itself)
+        (1..3).map(&.to_u64).sum(&.itself)
       )
       subject.catch(source).should_not be_valid
     end
@@ -37,7 +36,7 @@ module Ameba::Rule::Performance
     context "macro" do
       it "doesn't report in macro scope" do
         source = Source.new %(
-          {{ [1, 2, 3].map(&.to_s).join }}
+          {{ [1, 2, 3].map(&.to_u64).sum }}
         )
         subject.catch(source).should be_valid
       end
@@ -45,15 +44,15 @@ module Ameba::Rule::Performance
 
     it "reports rule, pos and message" do
       s = Source.new %(
-        (1..3).map(&.to_s).join
+        (1..3).map(&.to_u64).sum
       ), "source.cr"
       subject.catch(s).should_not be_valid
       issue = s.issues.first
 
       issue.rule.should_not be_nil
       issue.location.to_s.should eq "source.cr:1:8"
-      issue.end_location.to_s.should eq "source.cr:1:24"
+      issue.end_location.to_s.should eq "source.cr:1:25"
-      issue.message.should eq "Use `join {...}` instead of `map {...}.join`"
+      issue.message.should eq "Use `sum {...}` instead of `map {...}.sum`"
     end
   end
 end

src/ameba/rule/performance/map_instead_of_block.cr

@@ -1,18 +1,16 @@
 module Ameba::Rule::Performance
-  # This rule is used to identify usage of `join/sum/product` calls
+  # This rule is used to identify usage of `sum/product` calls
   # that follow `map`.
   #
   # For example, this is considered inefficient:
   #
   # ```
-  # (1..3).map(&.to_s).join('.')
   # (1..3).map(&.*(2)).sum
   # ```
   #
   # And can be written as this:
   #
   # ```
-  # (1..3).join('.', &.to_s)
   # (1..3).sum(&.*(2))
   # ```
   #
@@ -25,10 +23,10 @@ module Ameba::Rule::Performance
   class MapInsteadOfBlock < Base
     properties do
       enabled false
-      description "Identifies usage of `join/sum/product` calls that follow `map`."
+      description "Identifies usage of `sum/product` calls that follow `map`."
     end
 
-    CALL_NAMES = %w(join sum product)
+    CALL_NAMES = %w(sum product)
     MAP_NAME   = "map"
     MSG        = "Use `%s {...}` instead of `map {...}.%s`"