[Nearby Presence] Implement FakePresenceService::GetLocalPublicCredentials

Implements FakePresenceService::GetLocalPublicCredentials and exposes
FakePresenceService::SetLocalPublicCredentialsResult to configure results for
testing.
PiperOrigin-RevId: 542383663

presence/fake_presence_service.cc

@@ -79,10 +79,16 @@ PresenceDeviceProvider* FakePresenceService::GetLocalDeviceProvider() {
   return nullptr;
 }
 
-// Not implemented.
 void FakePresenceService::GetLocalPublicCredentials(
     const CredentialSelector& credential_selector,
-    GetPublicCredentialsResultCallback callback) {}
+    GetPublicCredentialsResultCallback callback) {
+  if (get_public_credentials_status_.ok()) {
+    std::move(callback.credentials_fetched_cb)(shared_credentials_);
+    return;
+  }
+
+  std::move(callback.credentials_fetched_cb)(get_public_credentials_status_);
+}
 
 void FakePresenceService::UpdateRemotePublicCredentials(
     absl::string_view manager_app_id, absl::string_view account_name,

presence/fake_presence_service.h

@@ -89,12 +89,20 @@ class FakePresenceService : public PresenceService {
     update_remote_public_credentials_status_ = status;
   }
 
+  void SetLocalPublicCredentialsResult(
+      absl::Status status,
+      std::vector<nearby::internal::SharedCredential> shared_credentials) {
+    get_public_credentials_status_ = status;
+    shared_credentials_ = shared_credentials;
+  }
+
  private:
   FakePresenceClient* most_recent_fake_presence_client_ = nullptr;
   std::vector<nearby::internal::SharedCredential> shared_credentials_;
   std::vector<nearby::internal::SharedCredential> remote_shared_credentials_;
   absl::Status gen_credentials_status_;
   absl::Status update_remote_public_credentials_status_;
+  absl::Status get_public_credentials_status_;
   ::nearby::internal::Metadata metadata_;
   ::nearby::Lender<PresenceService*> lender_{this};
 };