Merge pull request #301 from crystal-ameba/Sija/style-redundant-parentheses-rule

Add `Style/RedundantParentheses` rule

spec/ameba/rule/style/redundant_parentheses_spec.cr

@@ -0,0 +1,101 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Style
+  subject = RedundantParentheses.new
+
+  describe RedundantParentheses do
+    {% for keyword in %w(if unless while until) %}
+      context "{{ keyword.id }}" do
+        it "reports if redundant parentheses are found" do
+          source = expect_issue subject, <<-CRYSTAL, keyword: {{ keyword }}
+            %{keyword}   (foo > 10)
+            _{keyword} # ^^^^^^^^^^ error: Redundant parentheses
+              foo
+            end
+            CRYSTAL
+
+          expect_correction source, <<-CRYSTAL
+            {{ keyword.id }}   foo > 10
+              foo
+            end
+            CRYSTAL
+        end
+      end
+    {% end %}
+
+    context "case" do
+      it "reports if redundant parentheses are found" do
+        source = expect_issue subject, <<-CRYSTAL
+          case (foo = @foo)
+             # ^^^^^^^^^^^^ error: Redundant parentheses
+          when String then "string"
+          when Symbol then "symbol"
+          end
+          CRYSTAL
+
+        expect_correction source, <<-CRYSTAL
+          case foo = @foo
+          when String then "string"
+          when Symbol then "symbol"
+          end
+          CRYSTAL
+      end
+    end
+
+    context "properties" do
+      context "#exclude_ternary=" do
+        it "skips ternary control expressions by default" do
+          expect_no_issues subject, <<-CRYSTAL
+            (foo > bar) ? true : false
+            CRYSTAL
+        end
+
+        it "allows to configure assignments" do
+          rule = Rule::Style::RedundantParentheses.new
+          rule.exclude_ternary = false
+
+          expect_issue rule, <<-CRYSTAL
+            (foo.empty?) ? true : false
+            # ^^^^^^^^^^ error: Redundant parentheses
+            CRYSTAL
+
+          expect_no_issues subject, <<-CRYSTAL
+            (foo && bar) ? true : false
+            (foo || bar) ? true : false
+            (foo = @foo) ? true : false
+            foo == 42 ? true : false
+            (foo = 42) ? true : false
+            (foo > 42) ? true : false
+            (foo >= 42) ? true : false
+            (3 >= foo >= 42) ? true : false
+            (3.in? 0..42) ? true : false
+            (yield 42) ? true : false
+            (foo rescue 42) ? true : false
+            CRYSTAL
+        end
+      end
+
+      context "#exclude_assignments=" do
+        it "reports assignments by default" do
+          expect_issue subject, <<-CRYSTAL
+            if (foo = @foo)
+             # ^^^^^^^^^^^^ error: Redundant parentheses
+              foo
+            end
+            CRYSTAL
+        end
+
+        it "allows to configure assignments" do
+          rule = Rule::Style::RedundantParentheses.new
+          rule.exclude_assignments = true
+
+          expect_no_issues rule, <<-CRYSTAL
+            if (foo = @foo)
+              foo
+            end
+            CRYSTAL
+        end
+      end
+    end
+  end
+end