fix(model): bump version if necessary after successful bulkSave()

lib/document.js

@@ -5422,6 +5422,22 @@ Document.prototype.$__hasOnlyPrimitiveValues = function $__hasOnlyPrimitiveValue
   }));
 };
 
+/*!
+ * Increment this document's version if necessary.
+ */
+
+Document.prototype._applyVersionIncrement = function _applyVersionIncrement() {
+  if (!this.$__.version) return;
+  const doIncrement = VERSION_INC === (VERSION_INC & this.$__.version);
+
+  this.$__.version = undefined;
+  if (doIncrement) {
+    const key = this.$__schema.options.versionKey;
+    const version = this.$__getValue(key) || 0;
+    this.$__setValue(key, version + 1); // increment version if was successful
+  }
+};
+
 /*!
  * Module exports.
  */

lib/model.js

@@ -523,22 +523,17 @@ Model.prototype.$__save = function(options, callback) {
       const versionBump = this.$__.version;
       // was this an update that required a version bump?
       if (versionBump && !this.$__.inserting) {
-        const doIncrement = VERSION_INC === (VERSION_INC & this.$__.version);
-        this.$__.version = undefined;
-        const key = this.$__schema.options.versionKey;
-        const version = this.$__getValue(key) || 0;
         if (numAffected <= 0) {
+          const key = this.$__schema.options.versionKey;
+          const version = this.$__getValue(key) || 0;
           // the update failed. pass an error back
           this.$__undoReset();
           const err = this.$__.$versionError ||
             new VersionError(this, version, this.$__.modifiedPaths);
           return callback(err, this);
         }
 
-        // increment version if was successful
-        if (doIncrement) {
-          this.$__setValue(key, version + 1);
-        }
+        this._applyVersionIncrement();
       }
       if (result != null && numAffected <= 0) {
         this.$__undoReset();
@@ -3666,6 +3661,8 @@ function handleSuccessfulWrite(document) {
     }
 
     document.$__reset();
+    document._applyVersionIncrement();
+
     document.schema.s.hooks.execPost('save', document, [document], {}, (err) => {
       if (err) {
         reject(err);

test/model.test.js

@@ -7015,6 +7015,53 @@ describe('Model', function() {
       );
     });
 
+    it('increments version key on successful save (gh-15800)', async function() {
+      // Arrange
+      const userSchema = new Schema({
+        name: [String],
+        email: { type: String, minLength: 3 }
+      });
+
+      const User = db.model('User', userSchema);
+      const user1 = new User({ name: ['123'], email: '12314' });
+      await user1.save();
+
+      // Act
+      const user = await User.findOne({ _id: user1._id });
+      assert.ok(user);
+
+      // Before, __v should be 0
+      assert.equal(user.__v, 0);
+
+      // markModified on array field (triggers $set)
+      user.markModified('name');
+      await User.bulkSave([user]);
+
+      const dbUser1 = await User.findById(user._id);
+      assert.equal(dbUser1.__v, 1);
+      assert.equal(user.__v, 1);
+
+      // Update another path and markModified
+      user.email = '1375';
+      await User.bulkSave([user]);
+      const dbUser2 = await User.findById(user._id);
+      assert.equal(dbUser2.__v, 1);
+      assert.equal(user.__v, 1);
+
+      let reloaded = await User.findById(user._id);
+      assert.equal(reloaded.__v, 1);
+
+      user.email = '1';
+      await assert.rejects(
+        () => User.bulkSave([user]),
+        /email.*is shorter than the minimum allowed length/
+      );
+      assert.equal(user.__v, 1);
+
+      reloaded = await User.findById(user._id);
+      assert.equal(reloaded.__v, 1);
+    });
+
     it('saves new documents with ordered: false (gh-15495)', async function() {
       const userSchema = new Schema({
         name: { type: String }