fix: do not raise error if same provider is registered twice or more

go.mod

@@ -2,7 +2,7 @@ module github.com/illuin-tech/goinject
 
 go 1.24.0
 
-require github.com/stretchr/testify v1.10.0
+require github.com/stretchr/testify v1.11.1
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect

go.sum

@@ -4,6 +4,8 @@ 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/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

injector.go

@@ -19,21 +19,22 @@ type Injector struct {
 
 // NewInjector builds up a new Injector out of a list of Modules with singleton scope
 func NewInjector(options ...Option) (*Injector, error) {
-	mod := &configuration{
-		bindings: make(map[*binding]bool),
-		scopes:   make(map[string]Scope),
+	conf := &configuration{
+		bindings:       []*binding{},
+		scopes:         make(map[string]Scope),
+		knownProviders: []*provideOption{},
 	}
 
-	for _, o := range options {
-		err := o.apply(mod)
+	for _, option := range options {
+		err := option.apply(conf)
 		if err != nil {
 			return nil, err
 		}
 	}
 
 	singletonScope := newSingletonScope()
-	mod.scopes[Singleton] = singletonScope
-	mod.scopes[PerLookUp] = newPerLookUpScope()
+	conf.scopes[Singleton] = singletonScope
+	conf.scopes[PerLookUp] = newPerLookUpScope()
 
 	injector := &Injector{
 		bindings:       make(map[reflect.Type]map[string][]*binding),
@@ -49,8 +50,8 @@ func NewInjector(options ...Option) (*Injector, error) {
 		scope:        Singleton,
 	}
 
-	injector.scopes = mod.scopes
-	for b := range mod.bindings {
+	injector.scopes = conf.scopes
+	for _, b := range conf.bindings {
 		_, ok := injector.bindings[b.typeof]
 		if !ok {
 			injector.bindings[b.typeof] = make(map[string][]*binding)

injector_test.go

@@ -685,3 +685,31 @@ func TestInjectorConfigurationError(t *testing.T) {
 		)
 	})
 }
+
+func TestNewInjectorShouldIgnoreMultipleBindings(t *testing.T) {
+	provider := Provide(func() int { return 32 })
+
+	inj, err := NewInjector(
+		provider,
+		provider,
+	)
+	assert.Nil(t, err)
+	err = inj.Invoke(context.Background(), func(val int) {
+		assert.Equal(t, 32, val)
+	})
+	assert.Nil(t, err)
+}
+
+func TestNewInjectorShouldIgnoreMultipleBindingsInDifferentModules(t *testing.T) {
+	sharedModule := Module("shared", Provide(func() int { return 32 }))
+
+	inj, err := NewInjector(
+		Module("module-A", sharedModule),
+		Module("module-B", sharedModule),
+	)
+	assert.Nil(t, err)
+	err = inj.Invoke(context.Background(), func(val int) {
+		assert.Equal(t, 32, val)
+	})
+	assert.Nil(t, err)
+}

module.go

@@ -3,11 +3,13 @@ package goinject
 import (
 	"fmt"
 	"reflect"
+	"slices"
 )
 
 type configuration struct {
-	bindings map[*binding]bool
-	scopes   map[string]Scope
+	bindings       []*binding
+	scopes         map[string]Scope
+	knownProviders []*provideOption
 }
 
 // Option enable to configure the given injector
@@ -47,6 +49,12 @@ type provideOption struct {
 }
 
 func (o *provideOption) apply(mod *configuration) error {
+	if slices.Contains(mod.knownProviders, o) {
+		// already registered, ignore
+		return nil
+	}
+	mod.knownProviders = append(mod.knownProviders, o)
+
 	if o.constructor == nil {
 		return newInjectorConfigurationError("cannot accept nil provider", nil)
 	}
@@ -77,7 +85,7 @@ func (o *provideOption) apply(mod *configuration) error {
 		}
 	}
 
-	mod.bindings[b] = true
+	mod.bindings = append(mod.bindings, b)
 	return nil
 }