Add tests for sftp backend, split out id tests

backend/id_test.go

@@ -0,0 +1,32 @@
+package backend_test
+
+import (
+	"testing"
+
+	"github.com/restic/restic/backend"
+)
+
+func TestID(t *testing.T) {
+	for _, test := range TestStrings {
+		id, err := backend.ParseID(test.id)
+		ok(t, err)
+
+		id2, err := backend.ParseID(test.id)
+		ok(t, err)
+		assert(t, id.Equal(id2), "ID.Equal() does not work as expected")
+
+		ret, err := id.EqualString(test.id)
+		ok(t, err)
+		assert(t, ret, "ID.EqualString() returned wrong value")
+
+		// test json marshalling
+		buf, err := id.MarshalJSON()
+		ok(t, err)
+		equals(t, "\""+test.id+"\"", string(buf))
+
+		var id3 backend.ID
+		err = id3.UnmarshalJSON(buf)
+		ok(t, err)
+		equals(t, id, id3)
+	}
+}