SERVER-51399 Validation errors for $expr should report result of evaluation, not result after coercion to a boolean

1 files changed, 13 insertions, 0 deletions

diff --git a/src/mongo/db/matcher/expression_expr_test.cpp b/src/mongo/db/matcher/expression_expr_test.cpp
index e9e2e6eab4b..6f88314a6f5 100644
--- a/src/mongo/db/matcher/expression_expr_test.cpp
+++ b/src/mongo/db/matcher/expression_expr_test.cpp
@@ -29,6 +29,7 @@
 
 #include "mongo/platform/basic.h"
 
+#include "mongo/base/checked_cast.h"
 #include "mongo/bson/json.h"
 #include "mongo/db/matcher/expression.h"
 #include "mongo/db/matcher/expression_expr.h"
@@ -76,6 +77,10 @@ public:
         return _matchExpression->matchesBSON(doc);
     }
 
+    ExprMatchExpression* getExprMatchExpression() {
+        return checked_cast<ExprMatchExpression*>(_matchExpression.get());
+    }
+
 private:
     const boost::intrusive_ptr<ExpressionContextForTest> _expCtx;
     std::unique_ptr<MatchExpression> _matchExpression;
@@ -722,5 +727,13 @@ TEST(ExprMatchTest, OptimizingExprAbsorbsAndOfAnd) {
     ASSERT_BSONOBJ_EQ(serialized, expectedSerialization);
 }
 
+TEST_F(ExprMatchTest, ExpressionEvaluationReturnsResultsCorrectly) {
+    createMatcher(fromjson("{$expr: -2}"));
+    BSONMatchableDocument document{BSONObj{}};
+    auto expressionResult = getExprMatchExpression()->evaluateExpression(&document);
+    ASSERT_TRUE(expressionResult.integral());
+    ASSERT_EQUALS(-2, expressionResult.coerceToInt());
+}
+
 }  // namespace
 }  // namespace mongo