Add caps.Type.MarshalJSON()

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>

caps/types.go

@@ -20,6 +20,7 @@
 package caps
 
 import (
+	"encoding/json"
 	"fmt"
 )
 
@@ -68,3 +69,8 @@ func (t *Type) Validate(c *Capability) error {
 
 // TypeLookupFn aids in looking up a Type by name
 type TypeLookupFn func(name string) *Type
+
+// MarshalJSON encodes a Type object as the name of the type.
+func (t *Type) MarshalJSON() ([]byte, error) {
+	return json.Marshal(t.Name)
+}

caps/types_test.go

@@ -20,6 +20,7 @@
 package caps
 
 import (
+	"encoding/json"
 	"testing"
 
 	. "gopkg.in/check.v1"
@@ -62,3 +63,9 @@ func (s *TypeSuite) TestValidateAttributes(c *C) {
 	err := testType.Validate(cap)
 	c.Assert(err, ErrorMatches, "attributes must be empty for now")
 }
+
+func (s *TypeSuite) TestMarhshalJSON(c *C) {
+	b, err := json.Marshal(testType)
+	c.Assert(err, IsNil)
+	c.Assert(b, DeepEquals, []byte(`"test"`))
+}