feat: improve error accessor (#86)

VERSION

@@ -1 +1 @@
-0.0.15
+0.0.16

go.mod

@@ -11,11 +11,14 @@ require (
 	golang.org/x/tools v0.25.0
 )
 
+require golang.org/x/sys v0.25.0 // indirect
+
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/h2non/parth v0.0.0-20190131123155-b4df798d6542 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/sirupsen/logrus v1.9.3
 	golang.org/x/mod v0.21.0 // indirect
 	golang.org/x/sync v0.8.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect

go.sum

@@ -26,8 +26,11 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
+github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
+github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
 github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
@@ -48,6 +51,9 @@ golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.25.0 h1:r+8e+loiHxRqhXVl6ML1nO3l1+oFoWbnlu2Ehimmi34=
+golang.org/x/sys v0.25.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
@@ -65,5 +71,6 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

test/reflect.go

@@ -5,48 +5,66 @@ import (
 	"unsafe"
 )
 
-// Error creates an Accessor for the given error to access and modify its
+// Error creates an accessor/build for the given error to access and modify its
 // unexported fields by field name.
-//
-// Example:
-//
-//	err := test.Error(errors.New("error message")).Set("text", "new message").Get("")
-//	fmt.Println(err.Error()) // Output: new message
-//
-//	err := test.Error(errors.New("error message")).Set("text", "new message").Get("text")
-//	fmt.Println(err) // Output: new message
 func Error(err error) *Accessor[error] {
 	return NewAccessor[error](err)
 }
 
 // Accessor allows you to access and modify unexported fields of a struct.
 type Accessor[T any] struct {
-	target T
+	target  T
+	wrapped bool
 }
 
-// NewAccessor creates a generic accessor for the given target.
+// NewAccessor creates a generic accessor/builder for a given target struct.
+// If the target is a pointer to a struct (template), the instance is stored
+// and modified. If the target is a struct, a pointer to a new instance of is
+// created, since a struct cannot be modified by reflection.
 func NewAccessor[T any](target T) *Accessor[T] {
-	return &Accessor[T]{target: target}
+	value := reflect.ValueOf(target)
+	if value.Kind() == reflect.Ptr && value.Elem().Kind() == reflect.Struct {
+		return &Accessor[T]{
+			target: value.Interface().(T),
+		}
+	} else if value.Kind() == reflect.Struct {
+		target = reflect.New(value.Type()).Interface().(T)
+
+		return &Accessor[T]{
+			target:  target,
+			wrapped: true,
+		}
+	}
+	panic("target must be a struct or pointer to struct")
 }
 
-// Set sets the value of the accessor target's field with the given name.
+// Set sets the value of the field with the given name. If the name is empty,
+// and of the same type the stored target instance is replaced by the given
+// value.
 func (a *Accessor[T]) Set(name string, value any) *Accessor[T] {
-	field := reflect.ValueOf(a.target).Elem().FieldByName(name)
-	// #nosec G103,G115 // This is a safe use of unsafe.Pointer.
-	reflect.NewAt(field.Type(), unsafe.Pointer(field.UnsafeAddr())).
-		Elem().Set(reflect.ValueOf(value))
-
+	if name != "" {
+		field := reflect.ValueOf(a.target).Elem().FieldByName(name)
+		// #nosec G103,G115 // This is a safe use of unsafe.Pointer.
+		reflect.NewAt(field.Type(), unsafe.Pointer(field.UnsafeAddr())).
+			Elem().Set(reflect.ValueOf(value))
+	} else if reflect.TypeOf(a.target) == reflect.TypeOf(value) {
+		a.target = value.(T)
+	} else {
+		panic("target must of compatible struct pointer type")
+	}
 	return a
 }
 
-// Get returns the value of the field with the given name. If the name is empty,
-// it returns the accessor target itself.
+// Get returns the value of the field with the given name. If the name is
+// empty, the stored target instance is returned.
 func (a *Accessor[T]) Get(name string) any {
-	if name == "" {
-		return a.target
+	if name != "" {
+		field := reflect.ValueOf(a.target).Elem().FieldByName(name)
+		// #nosec G103,G115 // This is a safe use of unsafe.Pointer.
+		return reflect.NewAt(field.Type(), unsafe.Pointer(field.UnsafeAddr())).
+			Elem().Interface()
+	} else if a.wrapped {
+		return reflect.ValueOf(a.target).Elem().Interface()
 	}
-	field := reflect.ValueOf(a.target).Elem().FieldByName(name)
-	// #nosec G103,G115 // This is a safe use of unsafe.Pointer.
-	return reflect.NewAt(field.Type(), unsafe.Pointer(field.UnsafeAddr())).
-		Elem().Interface()
+	return a.target
 }

test/reflect_test.go

@@ -5,19 +5,129 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/tkrop/go-testing/mock"
 	"github.com/tkrop/go-testing/test"
 )
 
+type Struct struct{ s string }
+
+func NewStruct(s string) Struct     { return Struct{s: s} }
+func NewPtrStruct(s string) *Struct { return &Struct{s: s} }
+
+type testAccessorParam struct {
+	target any
+	setup  func(*test.Accessor[any])
+	expect mock.SetupFunc
+	check  func(test.Test, *test.Accessor[any])
+}
+
+var testAccessorParams = map[string]testAccessorParam{
+	"test invalid type": {
+		target: int(1),
+		expect: test.Panic("target must be a struct or pointer to struct"),
+	},
+
+	"test struct get is empty - no copy possible": {
+		target: NewStruct("test get"),
+		check: func(t test.Test, a *test.Accessor[any]) {
+			assert.Equal(t, "", a.Get("s"))
+			assert.Equal(t, NewStruct(""), a.Get(""))
+		},
+	},
+
+	"test struct set": {
+		target: NewStruct("test set"),
+		setup: func(a *test.Accessor[any]) {
+			a.Set("s", "test set first").
+				Set("s", "test set final")
+		},
+		check: func(t test.Test, a *test.Accessor[any]) {
+			assert.Equal(t, "test set final", a.Get("s"))
+			assert.Equal(t, NewStruct("test set final"), a.Get(""))
+		},
+	},
+
+	"test struct reset no pointer": {
+		target: NewStruct("test reset"),
+		setup: func(a *test.Accessor[any]) {
+			a.Set("s", "test reset first").
+				Set("", NewStruct("test reset final"))
+		},
+		expect: test.Panic("target must of compatible struct pointer type"),
+	},
+
+	"test struct reset pointer": {
+		target: NewStruct("test reset"),
+		setup: func(a *test.Accessor[any]) {
+			a.Set("s", "test reset first").
+				Set("", NewPtrStruct("test reset final"))
+		},
+		check: func(t test.Test, a *test.Accessor[any]) {
+			assert.Equal(t, "test reset final", a.Get("s"))
+			assert.Equal(t, NewStruct("test reset final"), a.Get(""))
+		},
+	},
+
+	"test ptr get": {
+		target: NewPtrStruct("test get"),
+		check: func(t test.Test, a *test.Accessor[any]) {
+			assert.Equal(t, "test get", a.Get("s"))
+			assert.Equal(t, NewPtrStruct("test get"), a.Get(""))
+		},
+	},
+
+	"test ptr set": {
+		target: NewPtrStruct("test set"),
+		setup: func(a *test.Accessor[any]) {
+			a.Set("s", "test set first").
+				Set("s", "test set final")
+		},
+		check: func(t test.Test, a *test.Accessor[any]) {
+			assert.Equal(t, "test set final", a.Get("s"))
+			assert.Equal(t, NewPtrStruct("test set final"), a.Get(""))
+		},
+	},
+
+	"test ptr reset": {
+		target: NewPtrStruct("test reset"),
+		setup: func(a *test.Accessor[any]) {
+			a.Set("s", "test reset first").
+				Set("", NewPtrStruct("test reset final"))
+		},
+		check: func(t test.Test, a *test.Accessor[any]) {
+			assert.Equal(t, "test reset final", a.Get("s"))
+			assert.Equal(t, NewPtrStruct("test reset final"), a.Get(""))
+		},
+	},
+}
+
+func TestAccessor(t *testing.T) {
+	test.Map(t, testAccessorParams).
+		Run(func(t test.Test, param testAccessorParam) {
+			// Given
+			mock.NewMocks(t).Expect(param.expect)
+			accessor := test.NewAccessor(param.target)
+
+			// When
+			if param.setup != nil {
+				param.setup(accessor)
+			}
+
+			// The
+			param.check(t, accessor)
+		})
+}
+
 type testErrorParam struct {
 	error error
 	setup func(*test.Accessor[error])
-	test  func(test.Test, *test.Accessor[error])
+	check func(test.Test, *test.Accessor[error])
 }
 
 var testErrorParams = map[string]testErrorParam{
 	"test get": {
 		error: errors.New("test get"),
-		test: func(t test.Test, a *test.Accessor[error]) {
+		check: func(t test.Test, a *test.Accessor[error]) {
 			assert.Equal(t, "test get", a.Get("s"))
 			assert.Equal(t, errors.New("test get"), a.Get(""))
 		},
@@ -29,7 +139,19 @@ var testErrorParams = map[string]testErrorParam{
 			a.Set("s", "test set first").
 				Set("s", "test set final")
 		},
-		test: func(t test.Test, a *test.Accessor[error]) {
+		check: func(t test.Test, a *test.Accessor[error]) {
+			assert.Equal(t, "test set final", a.Get("s"))
+			assert.Equal(t, errors.New("test set final"), a.Get(""))
+		},
+	},
+
+	"test reset": {
+		error: errors.New("test set"),
+		setup: func(a *test.Accessor[error]) {
+			a.Set("s", "test set first").
+				Set("", errors.New("test set final"))
+		},
+		check: func(t test.Test, a *test.Accessor[error]) {
 			assert.Equal(t, "test set final", a.Get("s"))
 			assert.Equal(t, errors.New("test set final"), a.Get(""))
 		},
@@ -48,6 +170,6 @@ func TestError(t *testing.T) {
 			}
 
 			// The
-			param.test(t, accessor)
+			param.check(t, accessor)
 		})
 }