func TestErrCyclicDependency(t *testing.T) {
Convey("Given I have cyclic dependencies", t, func() {
injector := katana.New().ProvideNew(&DepA{}, func(depB *DepB, depD *DepD) *DepA {
return &DepA{depB, depD}
})
injector.ProvideNew(&DepB{}, func() *DepB {
return &DepB{}
})
injector.ProvideNew(&DepC{}, func(dep *DepA) *DepC {
return &DepC{dep}
})
injector.ProvideNew(&DepD{}, func(dep *DepC) *DepD {
return &DepD{dep}
})
Convey("When I resolve the cyclic dependency", func() {
var dep *DepA
resolveWithCyclicDependency := func() {
injector.Resolve(&dep)
}
Convey("Then all dependencies are resolved recursively", func() {
So(resolveWithCyclicDependency, should.Panic)
})
})
})
}
func TestKatanaProvide(t *testing.T) {
Convey("Given I have an instance of katana injector with a few value providers", t, func() {
depA := &Dependency{}
depB := Dependency{}
injector := katana.New().Provide(depA, depB)
Convey("When I resolve instances of the provided values", func() {
var depA1, depA2 *Dependency
var depB1, depB2 Dependency
injector.Resolve(&depA1, &depA2, &depB1, &depB2)
Convey("Then instances of the same type are the same", func() {
So(depA1, should.NotBeNil)
So(depA2, should.NotBeNil)
So(depA1, should.Equal, depA2)
So(depB1, should.NotBeNil)
So(depB2, should.NotBeNil)
So(depB1, should.NotEqual, depB2)
So(depB1, should.Resemble, depB2)
})
})
})
}
func TestKatanaProvideNewInstance(t *testing.T) {
Convey("Given I have an instance of katana injector with a new instance provider of a dependency", t, func() {
injector := katana.New().ProvideNew(&Dependency{}, func() *Dependency {
return &Dependency{}
})
Convey("When I resolve multiple instances of the provided dependency", func() {
var dep1, dep2 *Dependency
injector.Resolve(&dep1, &dep2)
Convey("Then the resolved dependnecies points to different memory address", func() {
So(dep1, should.NotEqual, dep2)
})
})
})
Convey("Given I have two new instance providers one for *Dependency and another one for *DependencyB", t, func() {
injector := katana.New().ProvideNew(&Dependency{}, func() *Dependency {
return &Dependency{}
})
injector.ProvideNew(&DependencyA{}, func(dep *Dependency) *DependencyA {
return &DependencyA{dep}
})
Convey("When I resolve multiple instances of *DependencyB which depends on *Dependency", func() {
var dep1, dep2 *DependencyA
injector.Resolve(&dep1, &dep2)
Convey("Then the resolved dependencies point to different memory addresses", func() {
So(dep1, should.NotEqual, dep2)
Convey("And its dependencies also point to different memory addresses", func() {
So(dep1.Dep, should.NotBeNil)
So(dep2.Dep, should.NotBeNil)
So(dep1.Dep, should.NotEqual, dep2.Dep)
})
})
})
})
}
func TestErrInvalidReference(t *testing.T) {
Convey("Given I have a provider registered for a given dependency", t, func() {
injector := katana.New().ProvideNew(Dependency{}, func() *Dependency {
return &Dependency{}
})
Convey("Then it panics resolving a reference that is a zero value", func() {
var ref *Dependency
resolvingZeroValue := func() { injector.Resolve(ref) }
So(resolvingZeroValue, should.Panic)
})
})
}
func TestErrInvalidProvider(t *testing.T) {
// TODO write test case to catch whether the error is properly built
Convey("Given I have a provider function with no return value for a given dependency", t, func() {
invalidProvider := func() {
katana.New().ProvideNew(&DependencyC{}, func() {})
}
Convey("Then it fails with an invalid provider error", func() {
So(invalidProvider, should.Panic)
})
})
Convey("Given I have a provider function with multiple return values for a given dependency", t, func() {
invalidProvider := func() {
katana.New().ProvideNew(&DependencyC{}, func() (*DependencyC, error) {
return nil, nil
})
}
Convey("Then it fails with an invalid provider error", func() {
So(invalidProvider, should.Panic)
})
})
}
func TestKatanaProvidesSingletonInstance(t *testing.T) {
Convey("Given I have an instance of katana injector with a singleton dependency provider", t, func() {
injector := katana.New().ProvideSingleton(&Dependency{}, func() *Dependency {
return &Dependency{}
})
Convey("When I resolve multiple instances of the provided dependency", func() {
var dep1, dep2 *Dependency
injector.Resolve(&dep1, &dep2)
Convey("Then the resolved dependencies points to the same memory address", func() {
So(dep1, should.Equal, dep2)
})
})
})
}
func TestInjectorClone(t *testing.T) {
Convey("Given I have an injector with a few injectables and cached instances", t, func() {
injector := katana.New()
injector.Provide(&DependencyB{})
injector.ProvideNew(&Dependency{}, func() *Dependency {
return &Dependency{}
})
injector.ProvideSingleton(&DependencyA{}, func(dep *Dependency) *DependencyA {
return &DependencyA{dep}
})
Convey("When I clone the injector", func() {
newInjector := injector.Clone()
Convey("Then the new injector inherits the original injector providers", func() {
var dep *Dependency
var depA *DependencyA
var depB *DependencyB
newInjector.Resolve(&dep, &depA, &depB)
So(dep, should.NotBeNil)
So(depA, should.NotBeNil)
So(depB, should.NotBeNil)
})
Convey("And I register new providers with the new injector", func() {
newInjector.ProvideSingleton((*InterfaceDependency)(nil), func() InterfaceDependency {
return &InterfaceDependencyImpl{}
})
Convey("Then the provider is available only in the cloned injector", func() {
var dep1, dep2 InterfaceDependency
newInjector.Resolve(&dep1)
So(dep1, should.NotBeNil)
resolveWithOriginalInjector := func() { injector.Resolve(&dep2) }
So(resolveWithOriginalInjector, should.Panic)
})
})
})
})
}
func TestKatanaProvideAs(t *testing.T) {
Convey("Given I have an instance of katana injector with an instance provided as an interface type", t, func() {
dep := &InterfaceDependencyImpl{}
injector := katana.New().ProvideAs((*InterfaceDependency)(nil), dep)
Convey("When I resolve a reference to the provided dependency", func() {
var depA InterfaceDependency
injector.Resolve(&depA)
Convey("Then the reference is successfully resolved", func() {
So(depA, should.NotBeNil)
So(depA, should.Equal, dep)
})
})
})
}
func TestKatanaProvidesNewInstanceOfInterfaceType(t *testing.T) {
Convey("Given I have a provider of an interface dependency type", t, func() {
injector := katana.New().ProvideNew((*InterfaceDependency)(nil), func() InterfaceDependency {
return &InterfaceDependencyImpl{}
})
Convey("When I resolve multiple instances of the provided dependency", func() {
var dep1, dep2 InterfaceDependency
injector.Resolve(&dep1, &dep2)
Convey("Then the dependencies are resolved", func() {
So(dep1, should.NotEqual, dep2)
So(dep1, should.HaveSameTypeAs, &InterfaceDependencyImpl{})
So(dep2, should.HaveSameTypeAs, &InterfaceDependencyImpl{})
})
})
})
}
func TestErrProviderAlreadyRegistered(t *testing.T) {
Convey("Given I have a provider registered for a given dependency", t, func() {
injector := katana.New().ProvideNew(&DependencyC{}, func() *DependencyC {
return &DependencyC{}
})
Convey("When I register another provider for that same dependency type", func() {
alreadyRegisteredProvider := func() {
injector.ProvideNew(&DependencyC{}, func() *DependencyC {
return &DependencyC{}
})
}
Convey("Then it fails with an already registered provider", func() {
So(alreadyRegisteredProvider, should.Panic)
})
})
})
}
func ExampleKatanaAPI() {
// Grabs a new instance of katana.Injector
injector := katana.New()
// Registers the given instance of Config to be provided as a singleton injectable
injector.Provide(Config{
DatastoreURL: "https://myawesomestartup.com/db",
CacheTTL: 20000,
})
// Registers a constructor function that always provides a new instance of *Cache
injector.ProvideNew(&Cache{}, func(config Config) *Cache {
return &Cache{config.CacheTTL}
})
// Registers a constructor function that always provides a new instance of *Datastore
// resolving its dependencies -- Config and *Cache -- as part of the process
injector.ProvideNew(&Datastore{}, func(config Config, cache *Cache) *Datastore {
return &Datastore{cache, config.DatastoreURL}
})
// Registers a constructor function that lazily provides the same instance of *AccountService
// resolving its dependencies -- *Datastore -- as part of the process.
injector.ProvideSingleton(&AccountService{}, func(db *Datastore) *AccountService {
return &AccountService{db}
})
var service1, service2 *AccountService
injector.Resolve(&service1, &service2)
fmt.Println("service1 == service2:", service1 == service2)
fmt.Println("service1.Datastore.URL:", service1.Datastore.URL)
fmt.Println("service1.Datastore.Cache.TTL:", service1.Datastore.Cache.TTL)
// Output:
// service1 == service2: true
// service1.Datastore.URL: https://myawesomestartup.com/db
// service1.Datastore.Cache.TTL: 20000
}
func ExampleHTTP() {
injector := katana.New().
ProvideNew(&Database{}, NewDatabase).
ProvideNew(&Renderer{}, NewRenderer)
http.HandleFunc("/users", func(w http.ResponseWriter, req *http.Request) {
var db *Database
var render *Renderer
// Clone creates a copy of the injector, isolating the new registered providers form other threads
// We don't want users sharing each other's requests/response writers...
injector.Clone().
ProvideAs((*http.ResponseWriter)(nil), w).
Provide(req).
Resolve(&render, &db)
render.JSON(200, db.AllUsers())
})
go func() {
log.Fatal(http.ListenAndServe(":8080", nil))
}()
done := make(chan bool)
go func() {
res, _ := http.Get("http://localhost:8080/users")
bytes, _ := ioutil.ReadAll(res.Body)
var users []*User
json.Unmarshal(bytes, &users)
fmt.Printf("Users: %v, %v", users[0].Name, users[1].Name)
// Output: Users: borges, diego
done <- true
}()
<-done
}
func TestKatanaResolvesTransitiveDependencies(t *testing.T) {
Convey("Given I have transitive dependencies", t, func() {
injector := katana.New().ProvideNew(&DependencyB{}, func(dep *DependencyA) *DependencyB {
return &DependencyB{dep}
})
injector.ProvideNew(&DependencyA{}, func(dep *Dependency) *DependencyA {
return &DependencyA{dep}
})
injector.Provide(&Dependency{})
Convey("When I resolve the root dep", func() {
var depA *DependencyB
injector.Resolve(&depA)
Convey("Then all dependencies are resolved recursively", func() {
So(depA, should.NotBeNil)
So(depA.Dep, should.NotBeNil)
So(depA.Dep.Dep, should.NotBeNil)
})
})
})
}