Delete request headers with undefined value.

request.js

@@ -323,6 +323,14 @@ Request.prototype.init = function (options) {
   }
   self.headers = self.headers ? copy(self.headers) : {}
 
+  // Delete headers with value undefined since they break
+  // ClientRequest.OutgoingMessage.setHeader in node 0.12
+  for (var headerName in self.headers) {
+    if (typeof self.headers[headerName] === 'undefined') {
+      delete self.headers[headerName]
+    }
+  }
+
   caseless.httpify(self, self.headers)
 
   if (!self.method) {

tests/test-defaults.js

@@ -23,6 +23,14 @@ tape('setup', function(t) {
       resp.end()
     })
 
+    s.on('/foo-no-test', function(req, resp) {
+      assert.equal(req.headers.foo, 'bar')
+      assert.equal('test' in req.headers, false)
+      assert.equal(req.method, 'GET')
+      resp.writeHead(200, {'Content-Type': 'text/plain'})
+      resp.end('TESTING!')
+    })
+
     s.on('/post', function (req, resp) {
       assert.equal(req.headers.foo, 'bar')
       assert.equal(req.headers['content-type'], null)
@@ -136,6 +144,16 @@ tape('merge headers', function(t) {
   })
 })
 
+tape('default undefined header', function(t) {
+  request.defaults({
+    headers: { foo: 'bar', test: undefined }
+  })(s.url + '/foo-no-test', function(e, r, b) {
+    t.equal(e, null)
+    t.equal(b, 'TESTING!')
+    t.end()
+  })
+})
+
 tape('post(string, object, function)', function(t) {
   request.defaults({
     headers: { foo: 'bar' }

tests/test-headers.js

@@ -18,6 +18,14 @@ s.on('/redirect/to', function(req, res) {
   res.end('ok')
 })
 
+s.on('/headers.json', function(req, res) {
+  res.writeHead(200, {
+    'Content-Type': 'application/json'
+  })
+
+  res.end(JSON.stringify(req.headers))
+})
+
 tape('setup', function(t) {
   s.listen(s.port, function() {
     t.end()
@@ -138,6 +146,22 @@ tape('upper-case Host header and redirect', function(t) {
   })
 })
 
+tape('undefined headers', function(t) {
+  request({
+    url: s.url + '/headers.json',
+    headers: {
+      'X-TEST-1': 'test1',
+      'X-TEST-2': undefined
+    },
+    json: true
+  }, function(err, res, body) {
+    t.equal(err, null)
+    t.equal(body['x-test-1'], 'test1')
+    t.equal(typeof body['x-test-2'], 'undefined')
+    t.end()
+  })
+})
+
 tape('cleanup', function(t) {
   s.close(function() {
     t.end()