diff --git a/README.rst b/README.rst
index 14f565a1..f2d27adb 100644
--- a/README.rst
+++ b/README.rst
@@ -172,6 +172,29 @@ The generated documents will not be installed with ``make install``.
 The online documentation is available at
 https://nghttp2.org/documentation/
 
+Unit tests
+----------
+
+Unit tests are done by simply running `make check`.
+
+Integration tests
+-----------------
+
+We have the integration tests for nghttpx proxy server.  The tests are
+written in `Go programming language <http://golang.org/>`_ and uses
+its testing framework.  We depends on the following libraries:
+
+* https://github.com/bradfitz/http2
+* https://github.com/tatsuhiro-t/go-nghttp2
+
+To run the tests, enter ``integration-tests`` directory and run::
+
+    $ sh setenv go test
+
+``setenv`` will set necessary environment variables to compile
+go-nghttp2 library (which uses cgo to interface nghttp2).  In side the
+tests, we use port 3009 to run test subject server.
+
 Client, Server and Proxy programs
 ---------------------------------
 
diff --git a/configure.ac b/configure.ac
index 9237b4ad..e932664b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -652,6 +652,7 @@ AC_CONFIG_FILES([
   python/Makefile
   python/setup.py
   integration-tests/config.go
+  integration-tests/setenv
   doc/Makefile
   doc/conf.py
   doc/index.rst
diff --git a/integration-tests/nghttpx_test.go b/integration-tests/nghttpx_test.go
index 33212668..ebed7e2a 100644
--- a/integration-tests/nghttpx_test.go
+++ b/integration-tests/nghttpx_test.go
@@ -240,3 +240,40 @@ func TestHTTP2InvalidRequestCL(t *testing.T) {
 		t.Errorf("status: %v; want %v", got, want)
 	}
 }
+
+func TestHTTP2DuplicateResponseCL(t *testing.T) {
+	st := newServerTester([]string{"--http2-bridge"}, t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("content-length", "1")
+		w.Header().Add("content-length", "2")
+	})
+	defer st.Close()
+
+	res, err := st.http2(requestParam{
+		name: "TestHTTP2DuplicateResponseCL",
+	})
+	if err != nil {
+		t.Errorf("Error st.http2() = %v", err)
+	}
+	want := 502
+	if got := res.status; got != want {
+		t.Errorf("status: %v; want %v", got, want)
+	}
+}
+
+func TestHTTP2InvalidResponseCL(t *testing.T) {
+	st := newServerTester([]string{"--http2-bridge"}, t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("content-length", "")
+	})
+	defer st.Close()
+
+	res, err := st.http2(requestParam{
+		name: "TestHTTP2InvalidResponseCL",
+	})
+	if err != nil {
+		t.Errorf("Error st.http2() = %v", err)
+	}
+	want := 502
+	if got := res.status; got != want {
+		t.Errorf("status: %v; want %v", got, want)
+	}
+}
diff --git a/integration-tests/server_tester.go b/integration-tests/server_tester.go
index d2b415b1..0ee251cf 100644
--- a/integration-tests/server_tester.go
+++ b/integration-tests/server_tester.go
@@ -2,10 +2,12 @@ package nghttp2
 
 import (
 	"bytes"
+	"crypto/tls"
 	"errors"
 	"fmt"
 	"github.com/bradfitz/http2"
 	"github.com/bradfitz/http2/hpack"
+	"github.com/tatsuhiro-t/go-nghttp2"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -48,8 +50,27 @@ type serverTester struct {
 }
 
 func newServerTester(args []string, t *testing.T, handler http.HandlerFunc) *serverTester {
-	ts := httptest.NewServer(handler)
+	ts := httptest.NewUnstartedServer(handler)
 
+	backendTLS := false
+	for _, k := range args {
+		if k == "--http2-bridge" {
+			backendTLS = true
+			break
+		}
+	}
+	if backendTLS {
+		nghttp2.ConfigureServer(ts.Config, &nghttp2.Server{})
+		// According to httptest/server.go, we have to set
+		// NextProtos separately for ts.TLS.  NextProtos set
+		// in nghttp2.ConfigureServer is effectively ignored.
+		ts.TLS = new(tls.Config)
+		ts.TLS.NextProtos = append(ts.TLS.NextProtos, "h2-14")
+		ts.StartTLS()
+		args = append(args, "-k")
+	} else {
+		ts.Start()
+	}
 	u, err := url.Parse(ts.URL)
 	if err != nil {
 		t.Fatalf("Error parsing URL from httptest.Server: %v", err)
diff --git a/integration-tests/setenv.in b/integration-tests/setenv.in
new file mode 100644
index 00000000..2c2d3c95
--- /dev/null
+++ b/integration-tests/setenv.in
@@ -0,0 +1,6 @@
+#!/bin/sh -e
+
+export CGO_CFLAGS="-I@abs_top_srcdir@/lib/includes -I@abs_top_builddir@/lib/includes"
+export CGO_LDFLAGS="-L@abs_top_builddir@/lib/.libs"
+export LD_LIBRARY_PATH="@abs_top_builddir@/lib/.libs"
+"$@"