remove old auth header on Auth() call

do.go

@@ -2,6 +2,7 @@ package ezhttp
 
 import (
 	"encoding/json"
+	"fmt"
 	"io"
 	"net/http"
 )
@@ -10,10 +11,28 @@ func Do(req *http.Request) (*http.Response, error) {
 	return http.DefaultClient.Do(req)
 }
 
-func ParseJsonResponse[T any](r io.Reader) (*T, error) {
+func ParseJsonResponse[T any](resp *http.Response) (*T, error) {
+	if resp.StatusCode/100 != 2 {
+		return nil, fmt.Errorf(
+			"request '%s' returned status code %s\nOutput: %s",
+			resp.Request.URL.String(),
+			resp.Status,
+			ReadAllString(resp.Body),
+		)
+	}
+
 	res := new(T)
-	if err := json.NewDecoder(r).Decode(res); err != nil {
+	if err := json.NewDecoder(resp.Body).Decode(res); err != nil {
 		return nil, err
 	}
 	return res, nil
 }
+
+func ReadAllString(r io.Reader) string {
+	data, err := io.ReadAll(r)
+	if err != nil {
+		return fmt.Errorf("could not read response body: %w", err).Error()
+	}
+
+	return string(data)
+}

request.go

@@ -92,6 +92,17 @@ func Query(keyValuePairs ...string) RequestModifier {
 	}
 }
 
+func RemoveQuery(keys ...string) RequestModifier {
+	return func(r *RequestBuilder) *RequestBuilder {
+		q := r.URL.Query()
+		for _, key := range keys {
+			q.Del(key)
+		}
+		r.URL.RawQuery = q.Encode()
+		return r
+	}
+}
+
 func QueryMap(query map[string]string) RequestModifier {
 	return func(r *RequestBuilder) *RequestBuilder {
 		q := r.URL.Query()
@@ -123,6 +134,15 @@ func Headers(keyValuePairs ...string) RequestModifier {
 	}
 }
 
+func RemoveHeaders(headers ...string) RequestModifier {
+	return func(r *RequestBuilder) *RequestBuilder {
+		for _, header := range headers {
+			r.Header.Del(header)
+		}
+		return r
+	}
+}
+
 func HeadersMap(headers map[string]string) RequestModifier {
 	return func(r *RequestBuilder) *RequestBuilder {
 		for key, value := range headers {
@@ -133,7 +153,10 @@ func HeadersMap(headers map[string]string) RequestModifier {
 }
 
 func Auth(auth AuthProvider) RequestModifier {
-	return Headers("Authentication", auth())
+	return chainMods(
+		RemoveHeaders("Authentication"),
+		Headers("Authentication", auth()),
+	)
 }
 
 func Basic(username, password string) AuthProvider {

utils.go

@@ -0,0 +1,10 @@
+package ezhttp
+
+func chainMods(mods ...RequestModifier) RequestModifier {
+	return func(r *RequestBuilder) *RequestBuilder {
+		for _, mod := range mods {
+			r = mod(r)
+		}
+		return r
+	}
+}