log no response time when using immediate

History.md

@@ -2,6 +2,7 @@ unreleased
 ==========
 
   * "dev" format will use same tokens as other formats
+  * `:response-time` token is now empty when immediate used
   * `:response-time` token is now monotonic
   * `:response-time` token has precision to 1 μs
   * fix `:status` + immediate output in node.js 0.8

index.js

@@ -203,8 +203,8 @@ exports.token('method', function(req){
  * response time in milliseconds
  */
 
-exports.token('response-time', function(req){
-  if (!req._startAt) return '';
+exports.token('response-time', function(req, res){
+  if (!res._header || !req._startAt) return '';
   var diff = process.hrtime(req._startAt);
   var ms = diff[0] * 1e3 + diff[1] * 1e-6;
   return ms.toFixed(3);

test/test.js

@@ -158,6 +158,21 @@ describe('logger()', function () {
           done()
         })
       })
+
+      it('should be empty before response', function (done) {
+        var server = createServer({
+          format: ':response-time',
+          immediate: true
+        })
+
+        request(server)
+        .get('/')
+        .end(function (err, res) {
+          if (err) return done(err)
+          lastLogLine.should.equal('-\n')
+          done()
+        })
+      })
     })
 
     describe(':status', function () {