storage: add reversion test

storage/reversion_test.go

@@ -0,0 +1,39 @@
+package storage
+
+import (
+	"bytes"
+	"math"
+	"reflect"
+	"testing"
+)
+
+// TestReversion tests that reversion could be encoded to and decoded from
+// bytes slice. Moreover, the lexicograph order of its byte slice representation
+// follows the order of (main, sub).
+func TestReversion(t *testing.T) {
+	tests := []reversion{
+		// order in (main, sub)
+		reversion{},
+		reversion{main: 1, sub: 0},
+		reversion{main: 1, sub: 1},
+		reversion{main: 2, sub: 0},
+		reversion{main: math.MaxInt64, sub: math.MaxInt64},
+	}
+
+	bs := make([][]byte, len(tests))
+	for i, tt := range tests {
+		b := newRevBytes()
+		revToBytes(tt, b)
+		bs[i] = b
+
+		if grev := bytesToRev(b); !reflect.DeepEqual(grev, tt) {
+			t.Errorf("#%d: reversion = %+v, want %+v", i, grev, tt)
+		}
+	}
+
+	for i := 0; i < len(tests)-1; i++ {
+		if bytes.Compare(bs[i], bs[i+1]) >= 0 {
+			t.Errorf("#%d: %v (%+v) should be smaller than %v (%+v)", i, bs[i], tests[i], bs[i+1], tests[i+1])
+		}
+	}
+}