Enable `Style/RedundantBegin` cop to avoid newly adding redundant begin block

Currently we sometimes find a redundant begin block in code review
(e.g. https://github.com/rails/rails/pull/33604#discussion_r209784205).

I'd like to enable `Style/RedundantBegin` cop to avoid that, since
rescue/else/ensure are allowed inside do/end blocks in Ruby 2.5
(https://bugs.ruby-lang.org/issues/12906), so we'd probably meets with
that situation than before.

4 files changed, 84 insertions, 106 deletions

diff --git a/activemodel/test/cases/attribute_methods_test.rb b/activemodel/test/cases/attribute_methods_test.rb
index 0cfc6f4b6b..ebb6cc542d 100644
--- a/activemodel/test/cases/attribute_methods_test.rb
+++ b/activemodel/test/cases/attribute_methods_test.rb
@@ -106,14 +106,12 @@ class AttributeMethodsTest < ActiveModel::TestCase
   end
 
   test "#define_attribute_method generates attribute method" do
-    begin
-      ModelWithAttributes.define_attribute_method(:foo)
+    ModelWithAttributes.define_attribute_method(:foo)
 
-      assert_respond_to ModelWithAttributes.new, :foo
-      assert_equal "value of foo", ModelWithAttributes.new.foo
-    ensure
-      ModelWithAttributes.undefine_attribute_methods
-    end
+    assert_respond_to ModelWithAttributes.new, :foo
+    assert_equal "value of foo", ModelWithAttributes.new.foo
+  ensure
+    ModelWithAttributes.undefine_attribute_methods
   end
 
   test "#define_attribute_method does not generate attribute method if already defined in attribute module" do
@@ -140,36 +138,30 @@ class AttributeMethodsTest < ActiveModel::TestCase
   end
 
   test "#define_attribute_method generates attribute method with invalid identifier characters" do
-    begin
-      ModelWithWeirdNamesAttributes.define_attribute_method(:'a?b')
+    ModelWithWeirdNamesAttributes.define_attribute_method(:'a?b')
 
-      assert_respond_to ModelWithWeirdNamesAttributes.new, :'a?b'
-      assert_equal "value of a?b", ModelWithWeirdNamesAttributes.new.send("a?b")
-    ensure
-      ModelWithWeirdNamesAttributes.undefine_attribute_methods
-    end
+    assert_respond_to ModelWithWeirdNamesAttributes.new, :'a?b'
+    assert_equal "value of a?b", ModelWithWeirdNamesAttributes.new.send("a?b")
+  ensure
+    ModelWithWeirdNamesAttributes.undefine_attribute_methods
   end
 
   test "#define_attribute_methods works passing multiple arguments" do
-    begin
-      ModelWithAttributes.define_attribute_methods(:foo, :baz)
+    ModelWithAttributes.define_attribute_methods(:foo, :baz)
 
-      assert_equal "value of foo", ModelWithAttributes.new.foo
-      assert_equal "value of baz", ModelWithAttributes.new.baz
-    ensure
-      ModelWithAttributes.undefine_attribute_methods
-    end
+    assert_equal "value of foo", ModelWithAttributes.new.foo
+    assert_equal "value of baz", ModelWithAttributes.new.baz
+  ensure
+    ModelWithAttributes.undefine_attribute_methods
   end
 
   test "#define_attribute_methods generates attribute methods" do
-    begin
-      ModelWithAttributes.define_attribute_methods(:foo)
+    ModelWithAttributes.define_attribute_methods(:foo)
 
-      assert_respond_to ModelWithAttributes.new, :foo
-      assert_equal "value of foo", ModelWithAttributes.new.foo
-    ensure
-      ModelWithAttributes.undefine_attribute_methods
-    end
+    assert_respond_to ModelWithAttributes.new, :foo
+    assert_equal "value of foo", ModelWithAttributes.new.foo
+  ensure
+    ModelWithAttributes.undefine_attribute_methods
   end
 
   test "#alias_attribute generates attribute_aliases lookup hash" do
@@ -182,38 +174,32 @@ class AttributeMethodsTest < ActiveModel::TestCase
   end
 
   test "#define_attribute_methods generates attribute methods with spaces in their names" do
-    begin
-      ModelWithAttributesWithSpaces.define_attribute_methods(:'foo bar')
+    ModelWithAttributesWithSpaces.define_attribute_methods(:'foo bar')
 
-      assert_respond_to ModelWithAttributesWithSpaces.new, :'foo bar'
-      assert_equal "value of foo bar", ModelWithAttributesWithSpaces.new.send(:'foo bar')
-    ensure
-      ModelWithAttributesWithSpaces.undefine_attribute_methods
-    end
+    assert_respond_to ModelWithAttributesWithSpaces.new, :'foo bar'
+    assert_equal "value of foo bar", ModelWithAttributesWithSpaces.new.send(:'foo bar')
+  ensure
+    ModelWithAttributesWithSpaces.undefine_attribute_methods
   end
 
   test "#alias_attribute works with attributes with spaces in their names" do
-    begin
-      ModelWithAttributesWithSpaces.define_attribute_methods(:'foo bar')
-      ModelWithAttributesWithSpaces.alias_attribute(:'foo_bar', :'foo bar')
+    ModelWithAttributesWithSpaces.define_attribute_methods(:'foo bar')
+    ModelWithAttributesWithSpaces.alias_attribute(:'foo_bar', :'foo bar')
 
-      assert_equal "value of foo bar", ModelWithAttributesWithSpaces.new.foo_bar
-    ensure
-      ModelWithAttributesWithSpaces.undefine_attribute_methods
-    end
+    assert_equal "value of foo bar", ModelWithAttributesWithSpaces.new.foo_bar
+  ensure
+    ModelWithAttributesWithSpaces.undefine_attribute_methods
   end
 
   test "#alias_attribute works with attributes named as a ruby keyword" do
-    begin
-      ModelWithRubyKeywordNamedAttributes.define_attribute_methods([:begin, :end])
-      ModelWithRubyKeywordNamedAttributes.alias_attribute(:from, :begin)
-      ModelWithRubyKeywordNamedAttributes.alias_attribute(:to, :end)
-
-      assert_equal "value of begin", ModelWithRubyKeywordNamedAttributes.new.from
-      assert_equal "value of end", ModelWithRubyKeywordNamedAttributes.new.to
-    ensure
-      ModelWithRubyKeywordNamedAttributes.undefine_attribute_methods
-    end
+    ModelWithRubyKeywordNamedAttributes.define_attribute_methods([:begin, :end])
+    ModelWithRubyKeywordNamedAttributes.alias_attribute(:from, :begin)
+    ModelWithRubyKeywordNamedAttributes.alias_attribute(:to, :end)
+
+    assert_equal "value of begin", ModelWithRubyKeywordNamedAttributes.new.from
+    assert_equal "value of end", ModelWithRubyKeywordNamedAttributes.new.to
+  ensure
+    ModelWithRubyKeywordNamedAttributes.undefine_attribute_methods
   end
 
   test "#undefine_attribute_methods removes attribute methods" do
diff --git a/activemodel/test/cases/secure_password_test.rb b/activemodel/test/cases/secure_password_test.rb
index 9ef1148be8..bbf443290b 100644
--- a/activemodel/test/cases/secure_password_test.rb
+++ b/activemodel/test/cases/secure_password_test.rb
@@ -206,16 +206,14 @@ class SecurePasswordTest < ActiveModel::TestCase
   end
 
   test "Password digest cost honors bcrypt cost attribute when min_cost is false" do
-    begin
-      original_bcrypt_cost = BCrypt::Engine.cost
-      ActiveModel::SecurePassword.min_cost = false
-      BCrypt::Engine.cost = 5
-
-      @user.password = "secret"
-      assert_equal BCrypt::Engine.cost, @user.password_digest.cost
-    ensure
-      BCrypt::Engine.cost = original_bcrypt_cost
-    end
+    original_bcrypt_cost = BCrypt::Engine.cost
+    ActiveModel::SecurePassword.min_cost = false
+    BCrypt::Engine.cost = 5
+
+    @user.password = "secret"
+    assert_equal BCrypt::Engine.cost, @user.password_digest.cost
+  ensure
+    BCrypt::Engine.cost = original_bcrypt_cost
   end
 
   test "Password digest cost can be set to bcrypt min cost to speed up tests" do
diff --git a/activemodel/test/cases/serializers/json_serialization_test.rb b/activemodel/test/cases/serializers/json_serialization_test.rb
index 625e0a427a..84efc8de0d 100644
--- a/activemodel/test/cases/serializers/json_serialization_test.rb
+++ b/activemodel/test/cases/serializers/json_serialization_test.rb
@@ -26,20 +26,18 @@ class JsonSerializationTest < ActiveModel::TestCase
   end
 
   test "should include root in json if include_root_in_json is true" do
-    begin
-      original_include_root_in_json = Contact.include_root_in_json
-      Contact.include_root_in_json = true
-      json = @contact.to_json
-
-      assert_match %r{^\{"contact":\{}, json
-      assert_match %r{"name":"Konata Izumi"}, json
-      assert_match %r{"age":16}, json
-      assert_includes json, %("created_at":#{ActiveSupport::JSON.encode(Time.utc(2006, 8, 1))})
-      assert_match %r{"awesome":true}, json
-      assert_match %r{"preferences":\{"shows":"anime"\}}, json
-    ensure
-      Contact.include_root_in_json = original_include_root_in_json
-    end
+    original_include_root_in_json = Contact.include_root_in_json
+    Contact.include_root_in_json = true
+    json = @contact.to_json
+
+    assert_match %r{^\{"contact":\{}, json
+    assert_match %r{"name":"Konata Izumi"}, json
+    assert_match %r{"age":16}, json
+    assert_includes json, %("created_at":#{ActiveSupport::JSON.encode(Time.utc(2006, 8, 1))})
+    assert_match %r{"awesome":true}, json
+    assert_match %r{"preferences":\{"shows":"anime"\}}, json
+  ensure
+    Contact.include_root_in_json = original_include_root_in_json
   end
 
   test "should include root in json (option) even if the default is set to false" do
@@ -134,19 +132,17 @@ class JsonSerializationTest < ActiveModel::TestCase
   end
 
   test "as_json should return a hash if include_root_in_json is true" do
-    begin
-      original_include_root_in_json = Contact.include_root_in_json
-      Contact.include_root_in_json = true
-      json = @contact.as_json
-
-      assert_kind_of Hash, json
-      assert_kind_of Hash, json["contact"]
-      %w(name age created_at awesome preferences).each do |field|
-        assert_equal @contact.send(field).as_json, json["contact"][field]
-      end
-    ensure
-      Contact.include_root_in_json = original_include_root_in_json
+    original_include_root_in_json = Contact.include_root_in_json
+    Contact.include_root_in_json = true
+    json = @contact.as_json
+
+    assert_kind_of Hash, json
+    assert_kind_of Hash, json["contact"]
+    %w(name age created_at awesome preferences).each do |field|
+      assert_equal @contact.send(field).as_json, json["contact"][field]
     end
+  ensure
+    Contact.include_root_in_json = original_include_root_in_json
   end
 
   test "from_json should work without a root (class attribute)" do
diff --git a/activemodel/test/cases/validations/confirmation_validation_test.rb b/activemodel/test/cases/validations/confirmation_validation_test.rb
index 8603a8ac5c..7bf15e4bee 100644
--- a/activemodel/test/cases/validations/confirmation_validation_test.rb
+++ b/activemodel/test/cases/validations/confirmation_validation_test.rb
@@ -66,24 +66,22 @@ class ConfirmationValidationTest < ActiveModel::TestCase
   end
 
   def test_title_confirmation_with_i18n_attribute
-    begin
-      @old_load_path, @old_backend = I18n.load_path.dup, I18n.backend
-      I18n.load_path.clear
-      I18n.backend = I18n::Backend::Simple.new
-      I18n.backend.store_translations("en",
-        errors: { messages: { confirmation: "doesn't match %{attribute}" } },
-        activemodel: { attributes: { topic: { title: "Test Title" } } })
-
-      Topic.validates_confirmation_of(:title)
-
-      t = Topic.new("title" => "We should be confirmed", "title_confirmation" => "")
-      assert_predicate t, :invalid?
-      assert_equal ["doesn't match Test Title"], t.errors[:title_confirmation]
-    ensure
-      I18n.load_path.replace @old_load_path
-      I18n.backend = @old_backend
-      I18n.backend.reload!
-    end
+    @old_load_path, @old_backend = I18n.load_path.dup, I18n.backend
+    I18n.load_path.clear
+    I18n.backend = I18n::Backend::Simple.new
+    I18n.backend.store_translations("en",
+      errors: { messages: { confirmation: "doesn't match %{attribute}" } },
+      activemodel: { attributes: { topic: { title: "Test Title" } } })
+
+    Topic.validates_confirmation_of(:title)
+
+    t = Topic.new("title" => "We should be confirmed", "title_confirmation" => "")
+    assert_predicate t, :invalid?
+    assert_equal ["doesn't match Test Title"], t.errors[:title_confirmation]
+  ensure
+    I18n.load_path.replace @old_load_path
+    I18n.backend = @old_backend
+    I18n.backend.reload!
   end
 
   test "does not override confirmation reader if present" do