From 20800ac7df054fae59991279fd7b87a7e9bcb8d4 Mon Sep 17 00:00:00 2001
From: Matt Broadstone <mbroadst@mongodb.com>
Date: Fri, 13 Dec 2019 09:26:31 -0500
Subject: [PATCH] fix(bulk): use original indexes as map for current op index

The fix for bulk introduced in v3.4.0 did not take into account
the index of the operation result when referring to the original
stored index map.

NODE-2383
---
 lib/bulk/common.js           |  2 +-
 test/functional/bulk.test.js | 37 ++++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/lib/bulk/common.js b/lib/bulk/common.js
index 894d8569c2..fea6c18e34 100644
--- a/lib/bulk/common.js
+++ b/lib/bulk/common.js
@@ -475,7 +475,7 @@ function mergeBatchResults(batch, bulkResult, err, result) {
   if (Array.isArray(result.writeErrors)) {
     for (let i = 0; i < result.writeErrors.length; i++) {
       const writeError = {
-        index: batch.originalIndexes[i],
+        index: batch.originalIndexes[result.writeErrors[i].index],
         code: result.writeErrors[i].code,
         errmsg: result.writeErrors[i].errmsg,
         op: batch.operations[result.writeErrors[i].index]
diff --git a/test/functional/bulk.test.js b/test/functional/bulk.test.js
index 434f48d40b..ff13afa832 100644
--- a/test/functional/bulk.test.js
+++ b/test/functional/bulk.test.js
@@ -1660,4 +1660,41 @@ describe('Bulk', function() {
         );
     });
   });
+
+  it('should preserve order of operation index in unordered bulk operation', function() {
+    const client = this.configuration.newClient();
+    return client.connect().then(() => {
+      this.defer(() => client.close());
+
+      const coll = client.db().collection('bulk_op_ordering_test');
+      function ignoreNsNotFound(err) {
+        if (!err.message.match(/ns not found/)) throw err;
+      }
+
+      return coll
+        .drop()
+        .catch(ignoreNsNotFound)
+        .then(() => {
+          const batch = coll.initializeUnorderedBulkOp();
+          batch.insert({ _id: 1, a: 0 });
+          batch.insert({ _id: 1, a: 0 });
+          batch.insert({ _id: 2, a: 0 });
+          batch.insert({ _id: 2, a: 0 });
+          return batch.execute();
+        })
+        .then(
+          () => {
+            throw new Error('expected a bulk error');
+          },
+          err => {
+            expect(err)
+              .to.have.property('writeErrors')
+              .with.length(2);
+
+            expect(err).to.have.nested.property('writeErrors[0].err.index', 1);
+            expect(err).to.have.nested.property('writeErrors[1].err.index', 3);
+          }
+        );
+    });
+  });
 });