Merge pull request #1 from xmidt-org/feature/simpler-option

allow custom types for options

option.go

@@ -5,24 +5,51 @@ package praetor
 
 import (
 	"net/http"
+	"reflect"
 
 	"github.com/hashicorp/consul/api"
-	"go.uber.org/multierr"
 )
 
 // Option is a functional option for tailoring the consul client
 // configuration prior to creating it.  Each option can modify the
 // *api.Config prior to it being passed to api.NewClient.
 type Option func(*api.Config) error
 
-// AsOption bundles one or more functions into a single Option.
-func AsOption[O ~func(*api.Config) error](opts ...O) Option {
-	return func(cfg *api.Config) (err error) {
-		for _, o := range opts {
-			err = multierr.Append(err, o(cfg))
+var (
+	optionType        = reflect.TypeOf(Option(nil))
+	noErrorOptionType = reflect.TypeOf((func(*api.Config))(nil))
+)
+
+// OptionFunc represents the types of functions that can be coerced into Options.
+type OptionFunc interface {
+	~func(*api.Config) error | ~func(*api.Config)
+}
+
+// AsOption coerces a function into an Option.
+func AsOption[OF OptionFunc](of OF) Option {
+	// trivial conversions
+	switch oft := any(of).(type) {
+	case Option:
+		return oft
+
+	case func(*api.Config):
+		return func(cfg *api.Config) error {
+			oft(cfg)
+			return nil
 		}
+	}
+
+	// now we convert to the underlying type
+	ofv := reflect.ValueOf(of)
+	if ofv.CanConvert(optionType) {
+		return ofv.Convert(optionType).Interface().(Option)
+	}
 
-		return
+	// there are only (2) types, so the other type must be it
+	f := ofv.Convert(noErrorOptionType).Interface().(func(*api.Config))
+	return func(cfg *api.Config) error {
+		f(cfg)
+		return nil
 	}
 }
 

option_test.go

@@ -0,0 +1,113 @@
+// SPDX-FileCopyrightText: 2023 Comcast Cable Communications Management, LLC
+// SPDX-License-Identifier: Apache-2.0
+
+package praetor
+
+import (
+	"errors"
+	"net/http"
+	"testing"
+
+	"github.com/hashicorp/consul/api"
+	"github.com/stretchr/testify/suite"
+)
+
+const testAddress = "localhost:1234"
+
+type OptionSuite struct {
+	suite.Suite
+}
+
+func (suite *OptionSuite) testAsOptionWithOption() {
+	suite.Run("Success", func() {
+		opt := Option(func(cfg *api.Config) error {
+			cfg.Address = testAddress
+			return nil
+		})
+
+		var cfg api.Config
+		err := AsOption(opt)(&cfg)
+		suite.NoError(err)
+		suite.Equal(testAddress, cfg.Address)
+	})
+
+	suite.Run("Fail", func() {
+		expectedErr := errors.New("expected")
+		opt := Option(func(cfg *api.Config) error {
+			return expectedErr
+		})
+
+		var cfg api.Config
+		err := AsOption(opt)(&cfg)
+		suite.ErrorIs(err, expectedErr)
+	})
+}
+
+func (suite *OptionSuite) testAsOptionWithClosure() {
+	suite.Run("Success", func() {
+		opt := func(cfg *api.Config) error {
+			cfg.Address = testAddress
+			return nil
+		}
+
+		var cfg api.Config
+		err := AsOption(opt)(&cfg)
+		suite.NoError(err)
+		suite.Equal(testAddress, cfg.Address)
+	})
+
+	suite.Run("Fail", func() {
+		expectedErr := errors.New("expected")
+		opt := func(cfg *api.Config) error {
+			return expectedErr
+		}
+
+		var cfg api.Config
+		err := AsOption(opt)(&cfg)
+		suite.ErrorIs(err, expectedErr)
+	})
+}
+
+func (suite *OptionSuite) testAsOptionNoError() {
+	opt := func(cfg *api.Config) {
+		cfg.Address = testAddress
+	}
+
+	var cfg api.Config
+	err := AsOption(opt)(&cfg)
+	suite.NoError(err)
+	suite.Equal(testAddress, cfg.Address)
+}
+
+func (suite *OptionSuite) testAsOptionCustomType() {
+	type TestFunc func(*api.Config)
+	var opt TestFunc = func(cfg *api.Config) {
+		cfg.Address = testAddress
+	}
+
+	var cfg api.Config
+	err := AsOption(opt)(&cfg)
+	suite.NoError(err)
+	suite.Equal(testAddress, cfg.Address)
+}
+
+func (suite *OptionSuite) TestAsOption() {
+	suite.Run("WithOption", suite.testAsOptionWithOption)
+	suite.Run("WithClosure", suite.testAsOptionWithClosure)
+	suite.Run("NoError", suite.testAsOptionNoError)
+	suite.Run("CustomType", suite.testAsOptionCustomType)
+}
+
+func (suite *OptionSuite) TestWithHTTPClient() {
+	c := new(http.Client)
+	var cfg api.Config
+	suite.NoError(
+		WithHTTPClient(c)(&cfg),
+	)
+
+	suite.Same(c, cfg.HttpClient)
+}
+
+func TestOption(t *testing.T) {
+	suite.Run(t, new(OptionSuite))
+}