New attempt to fix this test. Could it be aborted connections?

crypto/tls/test/tls_integration_test.go

@@ -17,6 +17,7 @@ import (
 	"time"
 
 	"github.com/gogo/status"
+	"github.com/hashicorp/go-cleanhttp"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -103,6 +104,7 @@ func newIntegrationClientServer(
 
 	serv, err := server.New(cfg)
 	require.NoError(t, err)
+	defer serv.Shutdown()
 
 	serv.HTTP.HandleFunc("/hello", func(w http.ResponseWriter, _ *http.Request) {
 		fmt.Fprintf(w, "OK")
@@ -136,12 +138,13 @@ func newIntegrationClientServer(
 	grpcHost := net.JoinHostPort("localhost", strconv.Itoa(grpcAddr.Port))
 
 	for _, tc := range tcs {
-		tlsClientConfig, err := tc.tlsConfig.GetTLSConfig()
-		require.NoError(t, err)
-
 		// HTTP
 		t.Run("HTTP/"+tc.name, func(t *testing.T) {
-			transport := &http.Transport{TLSClientConfig: tlsClientConfig, MaxIdleConnsPerHost: 100} // DefaultMaxIdleConnsPerHost is 2
+			tlsClientConfig, err := tc.tlsConfig.GetTLSConfig()
+			require.NoError(t, err)
+
+			transport := cleanhttp.DefaultTransport()
+			transport.TLSClientConfig = tlsClientConfig
 			client := &http.Client{Transport: transport}
 
 			resp, err := client.Get(httpURL)
@@ -150,6 +153,7 @@ func newIntegrationClientServer(
 			}
 			if tc.httpExpectError != nil {
 				tc.httpExpectError(t, err)
+				time.Sleep(500 * time.Millisecond) // This prevents test flakiness: See https://go-review.googlesource.com/c/go/+/527196/6/src/net/http/server.go
 				return
 			}
 			if err != nil {
@@ -193,10 +197,7 @@ func newIntegrationClientServer(
 				assert.Equal(t, grpc_health_v1.HealthCheckResponse_SERVING, resp.Status)
 			}
 		})
-
 	}
-
-	serv.Shutdown()
 }
 
 func TestServerWithoutTlsEnabled(t *testing.T) {