diff --git a/hid/main_test.go b/hid/main_test.go
new file mode 100644
index 0000000..90a55f6
--- /dev/null
+++ b/hid/main_test.go
@@ -0,0 +1,139 @@
+//
+// Copyright (c) 2015 - 2018, Přemysl Janouch <p@janouch.name>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+//
+
+package main
+
+import (
+	"crypto/tls"
+	"net"
+	"os"
+	"reflect"
+	"syscall"
+	"testing"
+)
+
+func TestSplitString(t *testing.T) {
+	var splitStringTests = []struct {
+		s, delims   string
+		ignoreEmpty bool
+		result      []string
+	}{
+		{",a,,bc", ",", false, []string{"", "a", "", "bc"}},
+		{",a,,bc", ",", true, []string{"a", "bc"}},
+		{"a,;bc,", ",;", false, []string{"a", "", "bc", ""}},
+		{"a,;bc,", ",;", true, []string{"a", "bc"}},
+		{"", ",", false, []string{""}},
+		{"", ",", true, nil},
+	}
+
+	for i, d := range splitStringTests {
+		got := splitString(d.s, d.delims, d.ignoreEmpty)
+		if !reflect.DeepEqual(got, d.result) {
+			t.Errorf("case %d: %v should be %v\n", i, got, d.result)
+		}
+	}
+}
+
+func socketpair() (*os.File, *os.File, error) {
+	pair, err := syscall.Socketpair(syscall.AF_UNIX, syscall.SOCK_STREAM, 0)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// See go #24331, this makes 1.11 use the internal poller
+	// while there wasn't a way to achieve that before.
+	if err := syscall.SetNonblock(int(pair[0]), true); err != nil {
+		return nil, nil, err
+	}
+	if err := syscall.SetNonblock(int(pair[1]), true); err != nil {
+		return nil, nil, err
+	}
+
+	fa := os.NewFile(uintptr(pair[0]), "a")
+	if fa == nil {
+		return nil, nil, os.ErrInvalid
+	}
+
+	fb := os.NewFile(uintptr(pair[1]), "b")
+	if fb == nil {
+		fa.Close()
+		return nil, nil, os.ErrInvalid
+	}
+
+	return fa, fb, nil
+}
+
+func TestDetectTLS(t *testing.T) {
+	detectTLSFromFunc := func(t *testing.T, writer func(net.Conn)) bool {
+		// net.Pipe doesn't use file descriptors, we need a socketpair.
+		sockA, sockB, err := socketpair()
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer sockA.Close()
+		defer sockB.Close()
+
+		fcB, err := net.FileConn(sockB)
+		if err != nil {
+			t.Fatal(err)
+		}
+		go writer(fcB)
+
+		fcA, err := net.FileConn(sockA)
+		if err != nil {
+			t.Fatal(err)
+		}
+		sc, err := fcA.(syscall.Conn).SyscallConn()
+		if err != nil {
+			t.Fatal(err)
+		}
+		return detectTLS(sc)
+	}
+
+	t.Run("SSL_2.0", func(t *testing.T) {
+		if !detectTLSFromFunc(t, func(fc net.Conn) {
+			// The obsolete, useless, unsupported SSL 2.0 record format.
+			_, _ = fc.Write([]byte{0x80, 0x01, 0x01})
+		}) {
+			t.Error("could not detect SSL")
+		}
+	})
+	t.Run("crypto_tls", func(t *testing.T) {
+		if !detectTLSFromFunc(t, func(fc net.Conn) {
+			conn := tls.Client(fc, &tls.Config{InsecureSkipVerify: true})
+			_ = conn.Handshake()
+		}) {
+			t.Error("could not detect TLS")
+		}
+	})
+	t.Run("text", func(t *testing.T) {
+		if detectTLSFromFunc(t, func(fc net.Conn) {
+			_, _ = fc.Write([]byte("ПРЕВЕД"))
+		}) {
+			t.Error("detected UTF-8 as TLS")
+		}
+	})
+	t.Run("EOF", func(t *testing.T) {
+		type connCloseWriter interface {
+			net.Conn
+			CloseWrite() error
+		}
+		if detectTLSFromFunc(t, func(fc net.Conn) {
+			_ = fc.(connCloseWriter).CloseWrite()
+		}) {
+			t.Error("detected EOF as TLS")
+		}
+	})
+}