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chain_test.go
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chain_test.go
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// Package alice implements a middleware chaining solution.
package alice
import (
"net/http"
"net/http/httptest"
"reflect"
"testing"
)
// A constructor for middleware
// that writes its own "tag" into the RW and does nothing else.
// Useful in checking if a chain is behaving in the right order.
func tagMiddleware(tag string) Constructor {
return func(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
_, _ = w.Write([]byte(tag))
h.ServeHTTP(w, r)
})
}
}
// Not recommended (https://golang.org/pkg/reflect/#Value.Pointer),
// but the best we can do.
func funcsEqual(f1, f2 interface{}) bool {
val1 := reflect.ValueOf(f1)
val2 := reflect.ValueOf(f2)
return val1.Pointer() == val2.Pointer()
}
var testApp = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
_, _ = w.Write([]byte("app\n"))
})
func TestNew(t *testing.T) {
c1 := func(h http.Handler) http.Handler {
return nil
}
c2 := func(h http.Handler) http.Handler {
return http.StripPrefix("potato", nil)
}
slice := []Constructor{c1, c2}
chain := New(slice...)
for k := range slice {
if !funcsEqual(chain.constructors[k], slice[k]) {
t.Error("New does not add constructors correctly")
}
}
}
func TestThenWorksWithNoMiddleware(t *testing.T) {
if !funcsEqual(New().Then(testApp), testApp) {
t.Error("Then does not work with no middleware")
}
}
func TestThenTreatsNilAsDefaultServeMux(t *testing.T) {
if New().Then(nil) != http.DefaultServeMux {
t.Error("Then does not treat nil as DefaultServeMux")
}
}
func TestThenFuncTreatsNilAsDefaultServeMux(t *testing.T) {
if New().ThenFunc(nil) != http.DefaultServeMux {
t.Error("ThenFunc does not treat nil as DefaultServeMux")
}
}
func TestThenFuncConstructsHandlerFunc(t *testing.T) {
fn := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(200)
})
chained := New().ThenFunc(fn)
rec := httptest.NewRecorder()
chained.ServeHTTP(rec, (*http.Request)(nil))
if reflect.TypeOf(chained) != reflect.TypeOf((http.HandlerFunc)(nil)) {
t.Error("ThenFunc does not construct HandlerFunc")
}
}
func TestThenOrdersHandlersCorrectly(t *testing.T) {
t1 := tagMiddleware("t1\n")
t2 := tagMiddleware("t2\n")
t3 := tagMiddleware("t3\n")
chained := New(t1, t2, t3).Then(testApp)
w := httptest.NewRecorder()
r, err := http.NewRequest("GET", "/", nil)
if err != nil {
t.Fatal(err)
}
chained.ServeHTTP(w, r)
if w.Body.String() != "t1\nt2\nt3\napp\n" {
t.Error("Then does not order handlers correctly")
}
}
func TestAppendAddsHandlersCorrectly(t *testing.T) {
chain := New(tagMiddleware("t1\n"), tagMiddleware("t2\n"))
newChain := chain.Append(tagMiddleware("t3\n"), tagMiddleware("t4\n"))
if len(chain.constructors) != 2 {
t.Error("chain should have 2 constructors")
}
if len(newChain.constructors) != 4 {
t.Error("newChain should have 4 constructors")
}
chained := newChain.Then(testApp)
w := httptest.NewRecorder()
r, err := http.NewRequest("GET", "/", nil)
if err != nil {
t.Fatal(err)
}
chained.ServeHTTP(w, r)
if w.Body.String() != "t1\nt2\nt3\nt4\napp\n" {
t.Error("Append does not add handlers correctly")
}
}
func TestAppendRespectsImmutability(t *testing.T) {
chain := New(tagMiddleware(""))
newChain := chain.Append(tagMiddleware(""))
if &chain.constructors[0] == &newChain.constructors[0] {
t.Error("Apppend does not respect immutability")
}
}
func TestExtendAddsHandlersCorrectly(t *testing.T) {
chain1 := New(tagMiddleware("t1\n"), tagMiddleware("t2\n"))
chain2 := New(tagMiddleware("t3\n"), tagMiddleware("t4\n"))
newChain := chain1.Extend(chain2)
if len(chain1.constructors) != 2 {
t.Error("chain1 should contain 2 constructors")
}
if len(chain2.constructors) != 2 {
t.Error("chain2 should contain 2 constructors")
}
if len(newChain.constructors) != 4 {
t.Error("newChain should contain 4 constructors")
}
chained := newChain.Then(testApp)
w := httptest.NewRecorder()
r, err := http.NewRequest("GET", "/", nil)
if err != nil {
t.Fatal(err)
}
chained.ServeHTTP(w, r)
if w.Body.String() != "t1\nt2\nt3\nt4\napp\n" {
t.Error("Extend does not add handlers in correctly")
}
}
func TestExtendRespectsImmutability(t *testing.T) {
chain := New(tagMiddleware(""))
newChain := chain.Extend(New(tagMiddleware("")))
if &chain.constructors[0] == &newChain.constructors[0] {
t.Error("Extend does not respect immutability")
}
}