The test demonstrates failure for the following scenario. A single-subscription
client calls unsubscribe immediately followed by a subscribe. It will fail when
it tries to receive the next pmessage/message because the client will be in
false pub_sub_mode. Here is why it is false: First, the 2nd subscribe sets
pub_sub_mode to true during send_command. Next, the unsubscribe's
return_reply sets pub_sub_mode to false. The 2nd subscribe's return_reply does
not re-set pub_sub_mode back to true. So the result is a client with false
pub_sub_mode that fails upon receipt of the next message or pmessage.
While using this module with the hiredis parser, I noticed that exceptions
thrown inside of subscribe/message/etc. callbacks would be reported as
parser error exceptions, which was confusing.
Example:
```
var client = require('./index').createClient();
client.on('subscribe', function() {
throw new Error('My Error');
});
client.subscribe('channel');
```
I would expect the above to throw 'My Error' as a simple exception, however,
when using the hiredis parser I get:
```
events.js:45
throw arguments[1]; // Unhandled 'error' event
^
Error: Redis reply parser error: Error: My Error
at RedisClient.<anonymous> (/Users/felix/code/node_redis/hiredis.js:4:9)
at RedisClient.emit (events.js:67:17)
at RedisClient.return_reply (/Users/felix/code/node_redis/index.js:457:22)
at HiredisReplyParser.<anonymous> (/Users/felix/code/node_redis/index.js:220:14)
at HiredisReplyParser.emit (events.js:64:17)
at HiredisReplyParser.execute (/Users/felix/code/node_redis/lib/parser/hiredis.js:35:22)
at RedisClient.on_data (/Users/felix/code/node_redis/index.js:365:27)
at Socket.<anonymous> (/Users/felix/code/node_redis/index.js:58:14)
...
```
The attached patch fixes this problem by changing the way the HiredisReplyParser
traps exceptions, and also provides a unit test for it.
Please let me know if you need any tweaks on the patch for landing it, I was
not quite sure where to put my test / how to structure it, since most test
cases seem to be integration tests at this point.
Also, if you would prefer an integration test for this, here you go:
``` javascript
var client = require('./index').createClient();
var assert = require('assert');
process.on('uncaughtException', function listener(err) {
process.removeListener('uncaughtException', listener);
// Drop the stack, otherwise the assert gets trapped by node
process.nextTick(function() {
assert.ok(!/parser error/.test(err.message), err.message);
client.quit();
});
});
client.on('subscribe', function() {
throw new Error('My Error');
});
client.subscribe('channel');
```
PS: If you wonder why this only affects pubsub events: This is because
RedisClient#return_reply does exception trapping differently for events than
it does for callbacks.
See: 3e95c55a03/index.js (L431)
Vs: 3e95c55a03/index.js (L447)
* connection error did not properly trigger reconnection logic [GH-85]
* client.hmget(key, [val1, val2]) was not expanding properly [GH-66]
* client.quit() while in pub/sub mode would throw an error [GH-87]
* client.multi(['hmset', 'key', {foo: 'bar'}]) fails [GH-92]
