Set correct expiry time for UK access token

uk_vat_service.go

@@ -136,7 +136,7 @@ func GenerateUKAccessToken(opts ValidatorOpts) (*UKAccessToken, error) {
 		return nil, ErrUnableToGenerateUKAccessToken{Err: err}
 	}
 	// set the expiration time to 1 minute before the actual expiration for safety
-	token.ExpiresAt = time.Now().Add(time.Duration(token.SecondsUntilExpires - 60))
+	token.ExpiresAt = time.Now().Add(time.Duration(token.SecondsUntilExpires-60) * time.Second)
 	if opts.IsUKTest {
 		token.IsTest = true
 	}

uk_vat_service_test.go

@@ -6,6 +6,7 @@ package vat
 import (
 	"errors"
 	"testing"
+	"time"
 )
 
 // test numbers to use with the UK VAT service API in their sandbox environment:
@@ -33,6 +34,14 @@ func TestUKVATService(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	// expect the token to be valid for 14400 seconds (4 hours),
+	// but with ExpireAt 60 seconds earlier to help ensure we generate a new one before old one expires
+	expectedExpiresAt := time.Now().Add(time.Duration(14400-60) * time.Second)
+	isExpiresAtCorrect := expectedExpiresAt.Sub(token.ExpiresAt).Seconds() <= 1 // 1 second leeway for test to run
+
+	if token.SecondsUntilExpires != 14400 || !isExpiresAtCorrect {
+		t.Errorf("Expected token to be valid for 14400 seconds, got %d", token.SecondsUntilExpires)
+	}
 	opts.UKAccessToken = token
 
 	for _, test := range ukTests {