Allow service override (#16)

You can now replace a service that already exists in the Builder.

builder.go

@@ -83,8 +83,8 @@ func (b *Builder) Add(defs ...Def) error {
 }
 
 func (b *Builder) add(def Def) error {
-	if err := b.checkName(def.Name); err != nil {
-		return err
+	if def.Name == "" {
+		return errors.New("name can not be empty")
 	}
 
 	// note that an empty scope is allowed
@@ -102,18 +102,6 @@ func (b *Builder) add(def Def) error {
 	return nil
 }
 
-func (b *Builder) checkName(name string) error {
-	if name == "" {
-		return errors.New("name can not be empty")
-	}
-
-	if b.IsDefined(name) {
-		return fmt.Errorf("name `%s` is already defined", name)
-	}
-
-	return nil
-}
-
 // Build creates a Container in the most generic scope
 // with all the definitions registered in the Builder.
 func (b *Builder) Build() Container {

builder_test.go

@@ -59,6 +59,30 @@ func TestIsDefined(t *testing.T) {
 	require.False(t, b.IsDefined("undefined"))
 }
 
+func TestServiceOverride(t *testing.T) {
+	b, _ := NewBuilder()
+
+	var err error
+
+	err = b.Add(Def{
+		Name: "name",
+		Build: func(ctn Container) (interface{}, error) {
+			return "first", nil
+		},
+	})
+	require.Nil(t, err)
+
+	err = b.Add(Def{
+		Name: "name",
+		Build: func(ctn Container) (interface{}, error) {
+			return "second", nil
+		},
+	})
+	require.Nil(t, err)
+
+	require.Equal(t, "second", b.Build().Get("name").(string))
+}
+
 func TestAddErrors(t *testing.T) {
 	b, _ := NewBuilder()
 
@@ -72,9 +96,6 @@ func TestAddErrors(t *testing.T) {
 	err = b.Add(Def{Name: "object", Scope: "undefined", Build: buildFunc})
 	require.NotNil(t, err, "should not be able to add a Def in an undefined scope")
 
-	err = b.Add(Def{Name: "name", Scope: App, Build: buildFunc})
-	require.NotNil(t, err, "should not be able to add a Def if the name is already used")
-
 	err = b.Add(Def{Name: "", Scope: App, Build: buildFunc})
 	require.NotNil(t, err, "should not be able to add a Def if the name is empty")
 

go.mod

@@ -1,7 +1,3 @@
 module github.com/sarulabs/di/v2
 
-require (
-	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/stretchr/testify v1.2.2
-)
+require github.com/stretchr/testify v1.3.0

go.sum

@@ -1,6 +1,7 @@
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
-github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=