remove old auth header on Auth() call

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
+	}
+}