Apparently creating a ton of http servers in the same process and doing a ton of reverse proxying makes nodejs mad at you.

bad-agent

$ cd /Nodejitsu/node-http-proxy
$ node --version
v0.4.1
$ vows test/*-test.js --spec

♢ node-http-proxy/forward-proxy

  When using server created by httpProxy.createServer() with forwarding enabled with no latency and a valid target server
    ✓ should receive 'hello localhost'
  When using server created by httpProxy.createServer() with forwarding enabled with no latency and without a valid forward server
    ✓ should receive 'hello localhost'
  When the tests are over
    ✓ the servers should clean up
 
♢ node-http-proxy

  When using server created by httpProxy.createServer() with no latency and without a valid target server
    ✓ should receive 500 responseCode
  When using server created by httpProxy.createServer() with no latency and a valid target server
    ✗ should receive 'hello localhost'
      » expected 'hello localhost',
	got	 undefined (==) // helpers.js:35
  When using server created by httpProxy.createServer() with latency and without a valid target server
    ✓ should receive 500 responseCode
  When using server created by httpProxy.createServer() with latency and a valid target server
    ✗ should receive 'hello localhost'
      » expected 'hello localhost',
	got	 'An error has occurred: {"stack":"Error: Parse Error\\n    at Socket.ondata (http.js:1183:22)\\n    at Socket._onReadable (net.js:654:27)\\n    at IOWatcher.onReadable [as callback] (net.js:156:10)","message":"Parse Error","bytesParsed":0}' (==) // helpers.js:35
  When the tests are over
    ✓ the servers should clean up
 
♢ node-http-proxy/proxy-table

  When using server created by httpProxy.createServer() when passed a routing table an incoming request to bar.com
    ✗ should receive 'hello bar.com'
      » expected 'hello bar.com',
	got	 undefined (==) // helpers.js:35
  When using server created by httpProxy.createServer() when passed a routing file an incoming request to bar.com
    ✗ should receive 'hello bar.com'
      » expected 'hello bar.com',
	got	 undefined (==) // helpers.js:35
  When using server created by httpProxy.createServer() when passed a routing table an incoming request to unknown.com
    ✓ should receive 404 responseCode
  When using server created by httpProxy.createServer() when passed a routing file an incoming request to unknown.com
    ✗ should receive 404 responseCode
    TypeError: Cannot read property 'statusCode' of undefined
    at Object.<anonymous> (/Users/Charlie/Nodejitsu/node-http-proxy/test/helpers.js:60:21)
    at runTest (/usr/local/lib/node/.npm/vows/0.5.6/package/lib/vows.js:95:26)
    at EventEmitter.<anonymous> (/usr/local/lib/node/.npm/vows/0.5.6/package/lib/vows.js:78:13)
    at EventEmitter.emit (events.js:42:17)
    at /usr/local/lib/node/.npm/vows/0.5.6/package/lib/vows/context.js:28:47
    at [object Object].callback (/usr/local/lib/node/.npm/vows/0.5.6/package/lib/vows/context.js:42:29)
    at ClientRequest.<anonymous> (/usr/local/lib/node/.npm/request/1.9.0/package/main.js:111:35)
    at ClientRequest.emit (events.js:42:17)
    at Socket.<anonymous> (http.js:1171:9)
    at Socket.emit (events.js:42:17)
  When using server created by httpProxy.createServer() when passed a routing table an incoming request to foo.com
    ✗ should receive 'hello foo.com'
      » expected 'hello foo.com',
	got	 'An error has occurred: {"stack":"Error: Parse Error\\n    at Socket.ondata (http.js:1183:22)\\n    at Socket._onReadable (net.js:654:27)\\n    at IOWatcher.onReadable [as callback] (net.js:156:10)","message":"Parse Error","bytesParsed":0}' (==) // helpers.js:35
  When using server created by httpProxy.createServer() when passed a routing file an incoming request to foo.com
    ✗ should receive 'hello foo.com'
      » expected 'hello foo.com',
	got	 'An error has occurred: {"stack":"Error: Parse Error\\n    at Socket.ondata (http.js:1183:22)\\n    at Socket._onReadable (net.js:654:27)\\n    at IOWatcher.onReadable [as callback] (net.js:156:10)","message":"Parse Error","bytesParsed":0}' (==) // helpers.js:35
  When using server created by httpProxy.createServer() when passed a routing file an incoming request to dynamic.com after the file has been modified
    ✓ should receive 'hello dynamic.com'
  When using an instance of ProxyTable combined with HttpProxy directly an incoming request to bar.com
    ✗ should receive 'hello bar.com'
      » expected 'hello bar.com',
	got	 undefined (==) // helpers.js:35
  When using an instance of ProxyTable combined with HttpProxy directly an incoming request to unknown.com
    ✗ should receive 404 responseCode
    TypeError: Cannot read property 'statusCode' of undefined
    at Object.<anonymous> (/Users/Charlie/Nodejitsu/node-http-proxy/test/helpers.js:60:21)
    at runTest (/usr/local/lib/node/.npm/vows/0.5.6/package/lib/vows.js:95:26)
    at EventEmitter.<anonymous> (/usr/local/lib/node/.npm/vows/0.5.6/package/lib/vows.js:78:13)
    at EventEmitter.emit (events.js:42:17)
    at /usr/local/lib/node/.npm/vows/0.5.6/package/lib/vows/context.js:28:47
    at [object Object].callback (/usr/local/lib/node/.npm/vows/0.5.6/package/lib/vows/context.js:42:29)
    at ClientRequest.<anonymous> (/usr/local/lib/node/.npm/request/1.9.0/package/main.js:111:35)
    at ClientRequest.emit (events.js:42:17)
    at Socket.<anonymous> (http.js:1239:27)
    at Socket.emit (events.js:42:17)

node.js:116
        throw e; // process.nextTick error, or 'error' event on first tick
        ^
TypeError: Cannot call method 'emit' of undefined
    at Socket.<anonymous> (http.js:1171:9)
    at Socket.emit (events.js:42:17)
    at Array.<anonymous> (net.js:799:27)
    at EventEmitter._tickCallback (node.js:108:26)

parse-error.json

{
  "message":"Parse Error",
  "bytesParsed":0
  "stack": [
    "Error: Parse Error",
    "at Socket.ondata (http.js:1183:22)",
    "at Socket._onReadable (net.js:654:27)"
    "IOWatcher.onReadable [as callback] (net.js:156:10)"
  ]
}

unhandled-exception

node.js:116
        throw e; // process.nextTick error, or 'error' event on first tick
        ^
TypeError: Cannot call method 'emit' of undefined
    at Socket.<anonymous> (http.js:1171:9)
    at Socket.emit (events.js:42:17)
    at Array.<anonymous> (net.js:799:27)
    at EventEmitter._tickCallback (node.js:108:26)