Add tests and emit UNCERTAIN_STATE errors

Author: Ruben Bridgewater

index.js

@@ -530,6 +530,8 @@ RedisClient.prototype.connection_gone = function (why) {
         //     error.message = 'Command aborted in uncertain state and queued for next connection.';
         // }
         this.flush_and_error(error, ['command_queue']);
+        error.message = 'Redis connection lost and commands aborted in uncertain state. They might have been processed.';
+        this.emit('error', error);
     }
 
     if (this.retry_max_delay !== null && this.retry_delay > this.retry_max_delay) {
@@ -1109,11 +1111,12 @@ Multi.prototype.execute_callback = function (err, replies) {
 
     if (err) {
         // The errors would be circular
-        err.errors = err.code !== 'CONNECTION_BROKEN' ? this.errors : [];
+        var connection_error = ['CONNECTION_BROKEN', 'UNCERTAIN_STATE'].indexOf(err.code) !== -1;
+        err.errors = connection_error ? [] : this.errors;
         if (this.callback) {
             this.callback(err);
-        } else if (err.code !== 'CONNECTION_BROKEN') {
-            // Exclude CONNECTION_BROKEN so that error won't be emitted twice
+            // Exclude connection errors so that those errors won't be emitted twice
+        } else if (!connection_error) {
             this._client.emit('error', err);
         }
         return;

test/commands/multi.spec.js

@@ -553,6 +553,19 @@ describe("The 'multi' method", function () {
                     });
                 });
 
+                it("emits error once if reconnecting after multi has been executed but not yet returned without callback", function (done) {
+                    helper.serverVersionAtLeast.call(this, client, [2, 6, 5]);
+
+                    client.on('error', function(err) {
+                        assert.strictEqual(err.code, 'UNCERTAIN_STATE');
+                        done();
+                    });
+
+                    client.multi().set("foo", 'bar').get('foo').exec();
+                    // Abort connection before the value returned
+                    client.stream.destroy();
+                });
+
             });
         });
     });

test/connection.spec.js

@@ -107,6 +107,20 @@ describe("connection tests", function () {
                     });
 
                 });
+
+                it("emits error once if reconnecting after command has been executed but not yet returned without callback", function (done) {
+                    client = redis.createClient.apply(redis.createClient, args);
+                    client.on('error', function(err) {
+                        assert.strictEqual(err.code, 'UNCERTAIN_STATE');
+                        done();
+                    });
+
+                    client.on('ready', function() {
+                        client.set("foo", 'bar');
+                        // Abort connection before the value returned
+                        client.stream.destroy();
+                    });
+                });
             });
 
             describe("when not connected", function () {