adding test for workforce pools for new option as requested by bojeil@; adding unit testing; go fmt

google/internal/externalaccount/basecredentials.go

@@ -78,6 +78,7 @@ var (
 		regexp.MustCompile(`^iamcredentials\.[^\.\s\/\\]+\.googleapis\.com$`),
 		regexp.MustCompile(`^[^\.\s\/\\]+-iamcredentials\.googleapis\.com$`),
 	}
+	validWorkforceAudiencePattern *regexp.Regexp = regexp.MustCompile(`//iam\.googleapis\.com/locations/[^/]+/workforcePools/`)
 )
 
 func validateURL(input string, patterns []*regexp.Regexp, scheme string) bool {
@@ -91,14 +92,17 @@ func validateURL(input string, patterns []*regexp.Regexp, scheme string) bool {
 	toTest := parsed.Host
 
 	for _, pattern := range patterns {
-
+		if pattern.MatchString(toTest) {
-		if valid := pattern.MatchString(toTest); valid {
 			return true
 		}
 	}
 	return false
 }
 
+func validateWorkforceAudience(input string) bool {
+	return validWorkforceAudiencePattern.MatchString(input)
+}
+
 // TokenSource Returns an external account TokenSource struct. This is to be called by package google to construct a google.Credentials.
 func (c *Config) TokenSource(ctx context.Context) (oauth2.TokenSource, error) {
 	return c.tokenSource(ctx, validTokenURLPatterns, validImpersonateURLPatterns, "https")
@@ -120,6 +124,13 @@ func (c *Config) tokenSource(ctx context.Context, tokenURLValidPats []*regexp.Re
 		}
 	}
 
+	if c.WorkforcePoolUserProject != "" {
+		valid := validateWorkforceAudience(c.Audience)
+		if !valid {
+			return nil, fmt.Errorf("oauth2/google: invalid Workforce Pool Audience provided while constructing tokenSource")
+		}
+	}
+
 	ts := tokenSource{
 		ctx:  ctx,
 		conf: c,
@@ -229,10 +240,10 @@ func (ts tokenSource) Token() (*oauth2.Token, error) {
 		ClientID:     conf.ClientID,
 		ClientSecret: conf.ClientSecret,
 	}
-	var options map[string]string
+	var options map[string]interface{}
-	if (ts.Config.WorkforcePoolUserProject != "") {
+	if conf.WorkforcePoolUserProject != "" {
-		options = map[string]string{
+		options = map[string]interface{}{
-			"userProject": ts.Config.WorkforcePoolUserProject,
+			"userProject": conf.WorkforcePoolUserProject,
 		}
 	}
 	stsResp, err := exchangeToken(ts.ctx, conf.TokenURL, &stsRequest, clientAuth, header, options)

google/internal/externalaccount/basecredentials_test.go

@@ -210,3 +210,41 @@ func TestValidateURLImpersonateURL(t *testing.T) {
 		})
 	}
 }
+
+func TestWorkforcePoolCreation(t *testing.T) {
+	var audienceValidatyTests = []struct {
+		audience      string
+		expectSuccess bool
+	}{
+		{"//iam.googleapis.com/locations/global/workforcePools/pool-id/providers/provider-id", true},
+		{"//iam.googleapis.com/locations/eu/workforcePools/pool-id/providers/provider-id", true},
+		{"//iam.googleapis.com/locations/eu/workforcePools/workloadIdentityPools/providers/provider-id", true},
+		{"identitynamespace:1f12345:my_provider", false},
+		{"//iam.googleapis.com/projects/123456/locations/global/workloadIdentityPools/pool-id/providers/provider-id", false},
+		{"//iam.googleapis.com/projects/123456/locations/eu/workloadIdentityPools/pool-id/providers/provider-id", false},
+		{"//iam.googleapis.com/projects/123456/locations/global/workloadIdentityPools/workforcePools/providers/provider-id", false},
+		{"//iamgoogleapis.com/locations/eu/workforcePools/pool-id/providers/provider-id", false},
+		{"//iam.googleapiscom/locations/eu/workforcePools/pool-id/providers/provider-id", false},
+		{"//iam.googleapis.com/locations/workforcePools/pool-id/providers/provider-id", false},
+		{"//iam.googleapis.com/locations/eu/workforcePool/pool-id/providers/provider-id", false},
+		{"//iam.googleapis.com/locations//workforcePool/pool-id/providers/provider-id", false},
+	}
+
+	ctx := context.Background()
+	for _, tt := range audienceValidatyTests {
+		t.Run(" "+tt.audience, func(t *testing.T) { // We prepend a space ahead of the test input when outputting for sake of readability.
+			config := testConfig
+			config.TokenURL = "https://sts.googleapis.com" // Setting the most basic acceptable tokenURL
+			config.ServiceAccountImpersonationURL = "https://iamcredentials.googleapis.com"
+			config.Audience = tt.audience
+			config.WorkforcePoolUserProject = "myProject"
+			_, err := config.TokenSource(ctx)
+
+			if tt.expectSuccess && err != nil {
+				t.Errorf("got %v but want nil", err)
+			} else if !tt.expectSuccess && err == nil {
+				t.Errorf("got nil but expected an error")
+			}
+		})
+	}
+}