Flush batch only after "commit" is called

Store batch operations in a gueue before execution. This will prevent
documents from being created/updated/deleted before `batch.commit()` is
even called. This issue was especially annoying when autoFlush is enabled.

Author: ilearnio

src/firestore.js

@@ -69,25 +69,42 @@ MockFirestore.prototype.runTransaction = function(transFunc) {
   });
 };
 
+var processBatchQueue = function (queue) {
+  _.forEach(queue, function (queueItem) {
+    var method = queueItem.method;
+    var doc = queueItem.args[0];
+    var data = queueItem.args[1];
+    var opts = queueItem.args[2];
+
+    if (method === 'set') {
+      if (opts && opts.merge === true) {
+        doc._update(data, { setMerge: true });
+      } else {
+        doc.set(data);
+      }
+    } else if (method === 'update') {
+      doc.update(data);
+    } else if (method === 'delete') {
+      doc.delete();
+    }
+  });
+}
+
 MockFirestore.prototype.batch = function () {
   var self = this;
+  var queue = [];
   return {
     set: function(doc, data, opts) {
-      var _opts = _.assign({}, { merge: false }, opts);
-      if (_opts.merge) {
-        doc._update(data, { setMerge: true });
-      }
-      else {
-        doc.set(data);
-      }
+      queue.push({ method: 'set', args: [doc, data, opts] });
     },
     update: function(doc, data) {
-      doc.update(data);
+      queue.push({ method: 'update', args: [doc, data] });
     },
     delete: function(doc) {
-      doc.delete();
+      queue.push({ method: 'delete', args: [doc] });
     },
     commit: function() {
+      processBatchQueue(queue);
       if (self.queue.events.length > 0) {
         self.flush();
       }

test/unit/firestore.js

@@ -185,5 +185,33 @@ describe('MockFirestore', function () {
 
       db.flush();
     });
+
+    context('when "batch.commit" is not called', function () {
+      afterEach(function () {
+        db.doc('col/batch-foo').delete();
+        db.doc('col/batch-bar').delete();
+        db.flush();
+      });
+
+      it('does not create documents', function (done) {
+        var batch = db.batch();
+        batch.set(db.doc('col/batch-foo'), { foo: 'fooo' });
+        batch.set(db.doc('col/batch-bar'), { bar: 'barr' });
+
+        expect(function () { db.flush() }).to.throw(Error)
+
+        var promises = [
+          db.doc('col/batch-foo').get(),
+          db.doc('col/batch-bar').get()
+        ]
+        db.flush()
+
+        Promise.all(promises).then(function (docs) {
+          expect(docs[0].exists).to.eq(false);
+          expect(docs[1].exists).to.eq(false);
+          done();
+        });
+      });
+    });
   });
 });