OIDC connector: Allow specifying empty prompt type

connector/oidc/oidc.go

@@ -76,7 +76,7 @@ type Config struct {
 	UserNameKey string `json:"userNameKey"`
 
 	// PromptType will be used fot the prompt parameter (when offline_access, by default prompt=consent)
-	PromptType string `json:"promptType"`
+	PromptType *string `json:"promptType"`
 
 	// OverrideClaimMapping will be used to override the options defined in claimMappings.
 	// i.e. if there are 'email' and `preferred_email` claims available, by default Dex will always use the `email` claim independent of the ClaimMapping.EmailKey.
@@ -242,8 +242,9 @@ func (c *Config) Open(id string, logger log.Logger) (conn connector.Connector, e
 	}
 
 	// PromptType should be "consent" by default, if not set
-	if c.PromptType == "" {
-		c.PromptType = "consent"
+	promptType := "consent"
+	if c.PromptType != nil {
+		promptType = *c.PromptType
 	}
 
 	clientID := c.ClientID
@@ -268,7 +269,7 @@ func (c *Config) Open(id string, logger log.Logger) (conn connector.Connector, e
 		allowedGroups:             c.AllowedGroups,
 		acrValues:                 c.AcrValues,
 		getUserInfo:               c.GetUserInfo,
-		promptType:                c.PromptType,
+		promptType:                promptType,
 		userIDKey:                 c.UserIDKey,
 		userNameKey:               c.UserNameKey,
 		overrideClaimMapping:      c.OverrideClaimMapping,

connector/oidc/oidc_test.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/go-jose/go-jose/v4"
 	"github.com/sirupsen/logrus"
+	"github.com/stretchr/testify/require"
 
 	"github.com/dexidp/dex/connector"
 )
@@ -584,6 +585,40 @@ func TestTokenIdentity(t *testing.T) {
 	}
 }
 
+func TestPromptType(t *testing.T) {
+	pointer := func(s string) *string {
+		return &s
+	}
+
+	tests := []struct {
+		name       string
+		promptType *string
+		res        string
+	}{
+		{name: "none", promptType: pointer("none"), res: "none"},
+		{name: "provided empty string", promptType: pointer(""), res: ""},
+		{name: "login", promptType: pointer("login"), res: "login"},
+		{name: "consent", promptType: pointer("consent"), res: "consent"},
+		{name: "default value", promptType: nil, res: "consent"},
+	}
+
+	testServer, err := setupServer(nil, true)
+	require.NoError(t, err)
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			conn, err := newConnector(Config{
+				Issuer:     testServer.URL,
+				Scopes:     []string{"openid", "groups"},
+				PromptType: tc.promptType,
+			})
+			require.NoError(t, err)
+
+			require.Equal(t, tc.res, conn.promptType)
+		})
+	}
+}
+
 func TestProviderOverride(t *testing.T) {
 	testServer, err := setupServer(map[string]any{
 		"sub":  "subvalue",