SERVER-24921 allow excluding only the _id field in $project

1 files changed, 8 insertions, 0 deletions

diff --git a/src/mongo/db/pipeline/parsed_exclusion_projection_test.cpp b/src/mongo/db/pipeline/parsed_exclusion_projection_test.cpp
index 5768b46882a..a9fb218d8ef 100644
--- a/src/mongo/db/pipeline/parsed_exclusion_projection_test.cpp
+++ b/src/mongo/db/pipeline/parsed_exclusion_projection_test.cpp
@@ -180,6 +180,14 @@ TEST(ExclusionProjectionExecutionTest, ShouldExcludeIdIfExplicitlyExcluded) {
     ASSERT_DOCUMENT_EQ(result, expectedResult);
 }
 
+TEST(ExclusionProjectionExecutionTest, ShouldExcludeIdAndKeepAllOtherFields) {
+    ParsedExclusionProjection exclusion;
+    exclusion.parse(BSON("_id" << false));
+    auto result = exclusion.applyProjection(Document{{"a", 1}, {"b", 2}, {"_id", "ID"}});
+    auto expectedResult = Document{{"a", 1}, {"b", 2}};
+    ASSERT_DOCUMENT_EQ(result, expectedResult);
+}
+
 //
 // Tests of execution of nested exclusions.
 //