Mark begin; end as empty expression

spec/ameba/rule/empty_expression_spec.cr

@@ -24,6 +24,12 @@ module Ameba
         a = nil
         a = ""
         a = 0
+
+        nil
+        :any.nil?
+
+        begin "" end
+        [nil] << nil
       )
       subject.catch(s).should be_valid
     end
@@ -69,6 +75,25 @@ module Ameba
         ()
       end
     )
+    it_detects_empty_expression %(
+      def method
+        begin
+        end
+      end
+    )
+    it_detects_empty_expression %(
+      begin; end
+    )
+    it_detects_empty_expression %(
+      begin
+        nil
+      end
+    )
+    it_detects_empty_expression %(
+      begin
+        ()
+      end
+    )
 
     it "reports rule, location and message" do
       s = Source.new %(