CDRIVER-4415 Allow bulkWriteResult to be optional (#1047)

Author: eramongodb

src/libmongoc/doc/mongoc_client_encryption_rewrap_many_datakey_result_get_bulk_write_result.rst

@@ -15,6 +15,8 @@ Synopsis
 
 Get the bulk write result set by a successful call to :symbol:`mongoc_client_encryption_rewrap_many_datakey()`.
 
+Returns ``NULL`` if no bulk write operation was executed or if the bulk write operation was unacknowledged.
+
 Parameters
 ----------
 

src/libmongoc/src/mongoc/mongoc-client-side-encryption.c

@@ -528,6 +528,12 @@ mongoc_client_encryption_rewrap_many_datakey_result_get_bulk_write_result (
       return NULL;
    }
 
+   /* bulkWriteResult may be empty if no result of a bulk write operation has
+    * been assigned to it. Treat as equivalent to an unset optional state. */
+   if (bson_empty (&result->bulk_write_result)) {
+      return NULL;
+   }
+
    return &result->bulk_write_result;
 }
 

src/libmongoc/tests/json/client_side_encryption/unified/rewrapManyDataKey.json

@@ -266,7 +266,9 @@
             }
           },
           "expectResult": {
-            "bulkWriteResult": {}
+            "bulkWriteResult": {
+              "$$exists": false
+            }
           }
         }
       ],

src/libmongoc/tests/unified/operation.c

@@ -350,7 +350,7 @@ operation_rewrap_many_data_key (test_t *test,
 
       bson_t doc = BSON_INITIALIZER;
 
-      {
+      if (bulk_write_result) {
          bson_t *const rewritten =
             rewrite_bulk_write_result (bulk_write_result);
          BSON_APPEND_DOCUMENT (&doc, "bulkWriteResult", rewritten);