[#369] status: Support WRONG_MAGIC_NUMBER code and detail

Define constant for `WrongMagicNumber` local code. Define constant
`DetailIDCorrect` for correct magic detail. Add `ResetDetails`
and `AppendDetails` method pair. Replace `SetDetails` method with new
`SetStatusDetails` function which can be implemented using new methods.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

status/details.go

@@ -0,0 +1,8 @@
+package status
+
+// details for WrongMagicNumber code.
+const (
+	// DetailIDCorrectMagic is an identifier of details with correct network magic
+	// which can be attached to WrongMagicNumber code.
+	DetailIDCorrectMagic = iota
+)

status/status.go

@@ -57,6 +57,8 @@ const (
 const (
 	// Internal is a local Code value for INTERNAL failure status.
 	Internal Code = iota
+	// WrongMagicNumber is a local Code value for WRONG_MAGIC_NUMBER failure status.
+	WrongMagicNumber
 )
 
 const (

status/test/generate.go

@@ -37,7 +37,7 @@ func Status(empty bool) *status.Status {
 	if !empty {
 		m.SetCode(765)
 		m.SetMessage("some string")
-		m.SetDetails(Details(false))
+		status.SetStatusDetails(m, Details(false))
 	}
 
 	return m

status/types.go

@@ -106,9 +106,22 @@ func (x *Status) IterateDetails(f func(*Detail) bool) {
 	}
 }
 
-// SetDetails sets Detail list of the Status.
+// ResetDetails empties the detail list.
-func (x *Status) SetDetails(v []*Detail) {
+func (x *Status) ResetDetails() {
 	if x != nil {
-		x.details = v
+		x.details = x.details[:0]
 	}
 }
+
+// AppendDetails appends the list of details to the Status.
+func (x *Status) AppendDetails(ds ...*Detail) {
+	if x != nil {
+		x.details = append(x.details, ds...)
+	}
+}
+
+// SetStatusDetails sets Detail list of the Status.
+func SetStatusDetails(dst *Status, ds []*Detail) {
+	dst.ResetDetails()
+	dst.AppendDetails(ds...)
+}