Ability to configure API base

Author: chrisjtwomey

README.md

@@ -115,6 +115,34 @@ func main() {
 
 ```
 
+# Defining a custom API host
+
+For testing purposes (eg. mocking validation responses in integration tests), you can configure the API base:
+
+```go
+package main
+
+import "github.com/teamwork/vat"
+
+func main() {
+	err := vat.Validate("NL123456789B01", ValidatorOpts{
+		APIBase: "http://mocker:8080",
+	})
+
+	var ukAccessToken *vat.UKAccessToken
+	ukAccessToken, _ = vat.GenerateUKAccessToken(vat.ValidatorOpts{
+		UKClientID:     "yourClientID",
+		UKClientSecret: "yourClientSecret",
+		IsUKTest:       true, // set this if you are testing this in their sandbox test API
+	})
+
+	err = vat.Validate("GB123456789", vat.ValidatorOpts{
+		UKAccessToken: ukAccessToken.Token,
+		APIBase: "http://mocker:8080",
+	})
+}
+```
+
 ## License
 
 MIT licensed. See the LICENSE file for details.

uk_vat_service.go

@@ -34,9 +34,14 @@ func (s *ukVATService) Validate(vatNumber string, opts ValidatorOpts) error {
 		return ErrInvalidCountryCode
 	}
 
+	baseURL := ukVatServiceURL(opts.IsUKTest)
+	if opts.APIBase != nil {
+		baseURL = *opts.APIBase
+	}
+
 	apiURL := fmt.Sprintf(
 		"%s/organisations/vat/check-vat-number/lookup/%s",
-		ukVatServiceURL(opts.IsUKTest),
+		baseURL,
 		vatNumber[2:],
 	)
 

validate.go

@@ -104,4 +104,5 @@ type ValidatorOpts struct {
 	UKClientSecret string
 	UKAccessToken  *UKAccessToken
 	IsUKTest       bool
+	APIBase        *string
 }

vies_service.go

@@ -19,12 +19,17 @@ type viesService struct{}
 
 // Validate returns whether the given VAT number is valid or not
 // There currently are no VIES options, so the "opts" parameter is here for interface compliance but ignored
-func (s *viesService) Validate(vatNumber string, _ ValidatorOpts) error {
+func (s *viesService) Validate(vatNumber string, opts ValidatorOpts) error {
 	if len(vatNumber) < 3 {
 		return ErrInvalidVATNumberFormat
 	}
 
-	res, err := s.lookup(s.getEnvelope(vatNumber))
+	serviceURL := viesServiceURL
+	if opts.APIBase != nil {
+		serviceURL = *opts.APIBase
+	}
+
+	res, err := s.lookup(serviceURL, s.getEnvelope(vatNumber))
 	if err != nil {
 		return ErrServiceUnavailable{Err: err}
 	}
@@ -105,12 +110,12 @@ func (s *viesService) getEnvelope(n string) string {
 }
 
 // lookup calls the VIES service to get info about the VAT number
-func (s *viesService) lookup(envelope string) (*http.Response, error) {
+func (s *viesService) lookup(serviceURL string, envelope string) (*http.Response, error) {
 	envelopeBuffer := bytes.NewBufferString(envelope)
 	client := http.Client{
 		Timeout: serviceTimeout,
 	}
-	return client.Post(viesServiceURL, "text/xml;charset=UTF-8", envelopeBuffer)
+	return client.Post(serviceURL, "text/xml;charset=UTF-8", envelopeBuffer)
 }
 
 const viesServiceURL = "https://ec.europa.eu/taxation_customs/vies/services/checkVatService"