google/externalaccount: validate tokenURL and ServiceAccountImpersonationURL

Change-Id: Iab70cc967fd97ac8e349a14760df0f8b02ddf074
GitHub-Last-Rev: ddf4dbd0b7
GitHub-Pull-Request: golang/oauth2#514
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/340569
Reviewed-by: Patrick Jones <ithuriel@google.com>
Reviewed-by: Cody Oss <codyoss@google.com>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
Trust: Cody Oss <codyoss@google.com>
Run-TryBot: Cody Oss <codyoss@google.com>
TryBot-Result: Go Bot <gobot@golang.org>

google/internal/externalaccount/impersonate_test.go

@@ -9,6 +9,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"regexp"
 	"testing"
 )
 
@@ -76,7 +77,11 @@ func TestImpersonation(t *testing.T) {
 	defer targetServer.Close()
 
 	testImpersonateConfig.TokenURL = targetServer.URL
-	ourTS := testImpersonateConfig.TokenSource(context.Background())
+	allURLs := regexp.MustCompile(".+")
+	ourTS, err := testImpersonateConfig.tokenSource(context.Background(), []*regexp.Regexp{allURLs}, []*regexp.Regexp{allURLs}, "http")
+	if err != nil {
+		t.Fatalf("Failed to create TokenSource: %v", err)
+	}
 
 	oldNow := now
 	defer func() { now = oldNow }()