Add Naming/BinaryOperatorParameterName rule

spec/ameba/rule/naming/binary_operator_parameter_name_spec.cr

@@ -0,0 +1,50 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Naming
+  subject = BinaryOperatorParameterName.new
+
+  describe BinaryOperatorParameterName do
+    it "ignores `other` parameter name in binary method definitions" do
+      expect_no_issues subject, <<-CRYSTAL
+        def +(other); end
+        def -(other); end
+        def *(other); end
+        CRYSTAL
+    end
+
+    it "ignores binary method definitions with arity other than 1" do
+      expect_no_issues subject, <<-CRYSTAL
+        def +; end
+        def +(foo, bar); end
+        def -; end
+        def -(foo, bar); end
+        CRYSTAL
+    end
+
+    it "ignores non-binary method definitions" do
+      expect_no_issues subject, <<-CRYSTAL
+        def foo(bar); end
+        def bąk(genus); end
+        CRYSTAL
+    end
+
+    it "reports binary methods definitions with incorrectly named parameter" do
+      expect_issue subject, <<-CRYSTAL
+        def +(foo); end
+            # ^ error: When defining the `+` operator, name its argument `other`
+        def -(foo); end
+            # ^ error: When defining the `-` operator, name its argument `other`
+        def *(foo); end
+            # ^ error: When defining the `*` operator, name its argument `other`
+        CRYSTAL
+    end
+
+    it "ignores methods from #excluded_operators" do
+      subject.excluded_operators.each do |op|
+        expect_no_issues subject, <<-CRYSTAL
+          def #{op}(foo); end
+          CRYSTAL
+      end
+    end
+  end
+end