test(auth): cover OIDC profile name fallbacks

packages/auth/providers/oidc/profile.ts

@@ -12,10 +12,10 @@ export const getProfileValueByPath = (profile: Profile, path: string): unknown =
   }, profile);
 };
 
-export const extractProfileName = (profile: Profile) => {
+export const extractProfileName = (profile: Profile): string | undefined => {
   if (!env.AUTH_OIDC_NAME_ATTRIBUTE_OVERWRITE) {
     // Use the name as the username if the preferred_username is an email address
-    return profile.preferred_username?.includes("@") ? profile.name : profile.preferred_username;
+    return (profile.preferred_username?.includes("@") ? profile.name : profile.preferred_username) ?? undefined;
   }
 
   const profileName = getProfileValueByPath(profile, env.AUTH_OIDC_NAME_ATTRIBUTE_OVERWRITE);

packages/auth/providers/oidc/test/profile.spec.ts

@@ -37,6 +37,35 @@ describe("getProfileValueByPath", () => {
 });
 
 describe("extractProfileName", () => {
+  test("uses preferred_username when overwrite is not set", () => {
+    const profile = {
+      sub: "user-id",
+      preferred_username: "johndoe",
+    } satisfies Profile;
+
+    expect(extractProfileName(profile)).toBe("johndoe");
+  });
+
+  test("uses name when preferred_username is an email", () => {
+    const profile = {
+      sub: "user-id",
+      preferred_username: "john@example.com",
+      name: "John Doe",
+    } satisfies Profile;
+
+    expect(extractProfileName(profile)).toBe("John Doe");
+  });
+
+  test("returns undefined when the fallback name is null", () => {
+    const profile = {
+      sub: "user-id",
+      preferred_username: "john@example.com",
+      name: null,
+    } satisfies Profile;
+
+    expect(extractProfileName(profile)).toBeUndefined();
+  });
+
   test("uses a nested name claim when configured", () => {
     mockEnv.AUTH_OIDC_NAME_ATTRIBUTE_OVERWRITE = "user.profile.display_name";
     const profile = {