From 859ffa862cd6213802931b7c8a589b04eea68c6b Mon Sep 17 00:00:00 2001
From: Faron Dutton <faron.dutton@insightglobal.com>
Date: Fri, 22 Nov 2024 10:18:19 -0500
Subject: [PATCH] Adds failing unit-test for issue #4839 NPE when projecting to
 an interface and using StringBasedAggregation

---
 .../repository/AbstractPersonRepositoryIntegrationTests.java | 5 +++++
 .../data/mongodb/repository/PersonRepository.java            | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/AbstractPersonRepositoryIntegrationTests.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/AbstractPersonRepositoryIntegrationTests.java
index 33720d2557..20e333e348 100644
--- a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/AbstractPersonRepositoryIntegrationTests.java
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/AbstractPersonRepositoryIntegrationTests.java
@@ -1275,6 +1275,11 @@ void readsClosedProjection() {
 		assertThat(repository.findClosedProjectionBy()).isNotEmpty();
 	}
 
+	@Test // https://github.com/spring-projects/spring-data-mongodb/issues/4839
+    void findAggregatedClosedProjectionBy() {
+        assertThat(repository.findAggregatedClosedProjectionBy()).isNotEmpty();
+    }
+
 	@Test // DATAMONGO-1865
 	void findFirstEntityReturnsFirstResultEvenForNonUniqueMatches() {
 		assertThat(repository.findFirstBy()).isNotNull();
diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/PersonRepository.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/PersonRepository.java
index c2036cabf9..09ead80617 100644
--- a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/PersonRepository.java
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/PersonRepository.java
@@ -386,6 +386,10 @@ Page<Person> findByCustomQueryLastnameAndAddressStreetInList(String lastname, Li
 	// DATAMONGO-1752
 	Iterable<PersonSummary> findClosedProjectionBy();
 
+    // https://github.com/spring-projects/spring-data-mongodb/issues/4839
+	@Aggregation("{ '$project': { _id : 0, firstName : 1, lastname : 1 } }")
+    Iterable<PersonSummary> findAggregatedClosedProjectionBy();
+
 	@Query(sort = "{ age : -1 }")
 	List<Person> findByAgeGreaterThan(int age);