New rule: redundant begin

spec/ameba/rule/redundant_begin_spec.cr

@@ -0,0 +1,213 @@
+require "../../spec_helper"
+
+module Ameba::Rule
+  describe RedundantBegin do
+    subject = RedundantBegin.new
+
+    it "passes if there is no redundant begin blocks" do
+      s = Source.new %(
+        def method
+          do_something
+        rescue
+          do_something_else
+        end
+
+        def method
+          do_something
+          do_something_else
+        ensure
+          handle_something
+        end
+
+        def method
+          yield
+        rescue
+        end
+
+        def method; end
+        def method; a = 1; rescue; end
+        def method; begin; rescue; end; end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "passes if there is a correct begin block in a handler" do
+      s = Source.new %q(
+        def handler_and_expression
+          begin
+            open_file
+          rescue
+            close_file
+          end
+          do_some_stuff
+        end
+
+        def multiple_handlers
+          begin
+            begin1
+          rescue
+          end
+
+          begin
+            begin2
+          rescue
+          end
+        rescue
+          do_something_else
+        end
+
+        def assign_and_begin
+          @result ||=
+            begin
+              do_something
+              do_something_else
+              returnit
+            end
+        rescue
+        end
+
+        def inner_handler
+          s = begin
+              rescue
+              end
+        rescue
+        end
+
+        def begin_and_expression
+          begin
+            a = 1
+            b = 2
+          end
+          expr
+        end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "fails if there is a redundant begin block" do
+      s = Source.new %q(
+        def method(a : String) : String
+          begin
+            open_file
+            do_some_stuff
+          ensure
+            close_file
+          end
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "fails if there is a redundant begin block in a method without args" do
+      s = Source.new %q(
+        def method
+          begin
+            open_file
+          ensure
+            close_file
+          end
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "fails if there is a redundant block in a method with return type" do
+      s = Source.new %q(
+        def method : String
+          begin
+            open_file
+          ensure
+            close_file
+          end
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "fails if there is a redundant block in a method with multiple args" do
+      s = Source.new %q(
+        def method(a : String,
+                  b : String)
+          begin
+            open_file
+          ensure
+            close_file
+          end
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "fails if there is a redundant block in a method with multiple args" do
+      s = Source.new %q(
+        def method(a : String,
+                  b : String
+        )
+          begin
+            open_file
+          ensure
+            close_file
+          end
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "fails if there is an inner redundant block" do
+      s = Source.new %q(
+        def method
+          begin
+            open_file
+          ensure
+            close_file
+          end
+        rescue
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "fails if there is a redundant block with yield" do
+      s = Source.new %q(
+        def method
+          begin
+            yield
+          ensure
+            close_file
+          end
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "fails if there is top level redundant block in a method" do
+      s = Source.new %q(
+        def method
+          begin
+            a = 1
+            b = 2
+          end
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "reports rule, pos and message" do
+      s = Source.new %q(
+        def method
+          begin
+            open_connection
+          ensure
+            close_connection
+          end
+        end
+      ), "source.cr"
+      subject.catch(s).should_not be_valid
+
+      error = s.errors.first
+      error.rule.should_not be_nil
+      error.location.to_s.should eq "source.cr:2:9"
+      error.message.should eq "Redundant `begin` block detected."
+    end
+  end
+end