Fix #2410

Signed-off-by: Jean-Laurent de Morlhon <jeanlaurent@morlhon.net>
Reviewed-by: David Gageot <david@gageot.net>

libmachine/drivers/serial.go

@@ -3,6 +3,8 @@ package drivers
 import (
 	"sync"
 
+	"encoding/json"
+
 	"github.com/docker/machine/libmachine/mcnflag"
 	"github.com/docker/machine/libmachine/state"
 )
@@ -164,3 +166,7 @@ func (d *SerialDriver) Stop() error {
 	defer d.Unlock()
 	return d.Driver.Stop()
 }
+
+func (d *SerialDriver) MarshalJSON() ([]byte, error) {
+	return json.Marshal(d.Driver)
+}

test/integration/core/inspect_format.bats

@@ -21,3 +21,9 @@ load ${BASE_TEST_DIR}/helpers.bash
   linecount=$(machine inspect -f '{{prettyjson .Driver}}' $NAME | wc -l)
   [[ "$linecount" -gt 1 ]]
 }
+
+@test "$DRIVER: check .Driver output is not flawed" {
+  run docker-machine inspect -f '{{.Driver.SSHUser}}' $NAME
+  [ "$status" -eq 0 ]
+  [[ ${output} == "docker" ]]
+}