Add db package

Add own db (storage) package with db.Storage interface, with Memory & Leveldb
implementations, and with tests.

Adapted with several changes from
https://github.com/iden3/go-iden3-core/tree/v0.0.8/db

db/test/test.go

@@ -0,0 +1,193 @@
+package test
+
+import (
+	"testing"
+
+	"github.com/iden3/go-merkletree/db"
+	"github.com/stretchr/testify/assert"
+)
+
+// TestReturnKnownErrIfNotExists checks that the implementation of the
+// db.Storage interface returns the expected error in the case that the value
+// is not found
+func TestReturnKnownErrIfNotExists(t *testing.T, sto db.Storage) {
+	k := []byte("key")
+
+	tx, err := sto.NewTx()
+	assert.Nil(t, err)
+	_, err = tx.Get(k)
+	assert.EqualError(t, err, db.ErrNotFound.Error())
+}
+
+// TestStorageInsertGet checks that the implementation of the db.Storage
+// interface behaves as expected
+func TestStorageInsertGet(t *testing.T, sto db.Storage) {
+	key := []byte("key")
+	value := []byte("data")
+
+	tx, err := sto.NewTx()
+	assert.Nil(t, err)
+	tx.Put(key, value)
+	v, err := tx.Get(key)
+	assert.Nil(t, err)
+	assert.Equal(t, value, v)
+	assert.Nil(t, tx.Commit())
+
+	tx, err = sto.NewTx()
+	assert.Nil(t, err)
+	v, err = tx.Get(key)
+	assert.Nil(t, err)
+	assert.Equal(t, value, v)
+}
+
+// TestStorageWithPrefix checks that the implementation of the db.Storage
+// interface behaves as expected for the WithPrefix method
+func TestStorageWithPrefix(t *testing.T, sto db.Storage) {
+	k := []byte{9}
+
+	sto1 := sto.WithPrefix([]byte{1})
+	sto2 := sto.WithPrefix([]byte{2})
+
+	// check within tx
+
+	sto1tx, err := sto1.NewTx()
+	assert.Nil(t, err)
+	sto1tx.Put(k, []byte{4, 5, 6})
+	v1, err := sto1tx.Get(k)
+	assert.Nil(t, err)
+	assert.Equal(t, v1, []byte{4, 5, 6})
+	assert.Nil(t, sto1tx.Commit())
+
+	sto2tx, err := sto2.NewTx()
+	assert.Nil(t, err)
+	sto2tx.Put(k, []byte{8, 9})
+	v2, err := sto2tx.Get(k)
+	assert.Nil(t, err)
+	assert.Equal(t, v2, []byte{8, 9})
+	assert.Nil(t, sto2tx.Commit())
+
+	// check outside tx
+
+	v1, err = sto1.Get(k)
+	assert.Nil(t, err)
+	assert.Equal(t, v1, []byte{4, 5, 6})
+
+	v2, err = sto2.Get(k)
+	assert.Nil(t, err)
+	assert.Equal(t, v2, []byte{8, 9})
+}
+
+// TestIterate checks that the implementation of the db.Storage interface
+// behaves as expected for the Iterate method
+func TestIterate(t *testing.T, sto db.Storage) {
+	r := []db.KV{}
+	lister := func(k []byte, v []byte) (bool, error) {
+		r = append(r, db.KV{K: db.Clone(k), V: db.Clone(v)})
+		return true, nil
+	}
+
+	sto1 := sto.WithPrefix([]byte{1})
+	err := sto1.Iterate(lister)
+	assert.Nil(t, err)
+	assert.Equal(t, 0, len(r))
+
+	sto1tx, _ := sto1.NewTx()
+	sto1tx.Put([]byte{1}, []byte{4})
+	sto1tx.Put([]byte{2}, []byte{5})
+	sto1tx.Put([]byte{3}, []byte{6})
+	assert.Nil(t, sto1tx.Commit())
+
+	sto2 := sto.WithPrefix([]byte{2})
+	sto2tx, _ := sto2.NewTx()
+	sto2tx.Put([]byte{1}, []byte{7})
+	sto2tx.Put([]byte{2}, []byte{8})
+	sto2tx.Put([]byte{3}, []byte{9})
+	assert.Nil(t, sto2tx.Commit())
+
+	r = []db.KV{}
+	err = sto1.Iterate(lister)
+	assert.Nil(t, err)
+	assert.Equal(t, 3, len(r))
+	assert.Equal(t, db.KV{[]byte{1}, []byte{4}}, r[0])
+	assert.Equal(t, db.KV{[]byte{2}, []byte{5}}, r[1])
+	assert.Equal(t, db.KV{[]byte{3}, []byte{6}}, r[2])
+
+	r = []db.KV{}
+	err = sto2.Iterate(lister)
+	assert.Nil(t, err)
+	assert.Equal(t, 3, len(r))
+	assert.Equal(t, db.KV{[]byte{1}, []byte{7}}, r[0])
+	assert.Equal(t, db.KV{[]byte{2}, []byte{8}}, r[1])
+	assert.Equal(t, db.KV{[]byte{3}, []byte{9}}, r[2])
+}
+
+// TestConcatTx checks that the implementation of the db.Storage interface
+// behaves as expected
+func TestConcatTx(t *testing.T, sto db.Storage) {
+	k := []byte{9}
+
+	sto1 := sto.WithPrefix([]byte{1})
+	sto2 := sto.WithPrefix([]byte{2})
+
+	// check within tx
+
+	sto1tx, err := sto1.NewTx()
+	if err != nil {
+		panic(err)
+	}
+	sto1tx.Put(k, []byte{4, 5, 6})
+	sto2tx, err := sto2.NewTx()
+	if err != nil {
+		panic(err)
+	}
+	sto2tx.Put(k, []byte{8, 9})
+
+	sto1tx.Add(sto2tx)
+	assert.Nil(t, sto1tx.Commit())
+
+	// check outside tx
+
+	v1, err := sto1.Get(k)
+	assert.Nil(t, err)
+	assert.Equal(t, v1, []byte{4, 5, 6})
+
+	v2, err := sto2.Get(k)
+	assert.Nil(t, err)
+	assert.Equal(t, v2, []byte{8, 9})
+}
+
+// TestList checks that the implementation of the db.Storage interface behaves
+// as expected
+func TestList(t *testing.T, sto db.Storage) {
+	sto1 := sto.WithPrefix([]byte{1})
+	r1, err := sto1.List(100)
+	assert.Nil(t, err)
+	assert.Equal(t, 0, len(r1))
+
+	sto1tx, _ := sto1.NewTx()
+	sto1tx.Put([]byte{1}, []byte{4})
+	sto1tx.Put([]byte{2}, []byte{5})
+	sto1tx.Put([]byte{3}, []byte{6})
+	assert.Nil(t, sto1tx.Commit())
+
+	sto2 := sto.WithPrefix([]byte{2})
+	sto2tx, _ := sto2.NewTx()
+	sto2tx.Put([]byte{1}, []byte{7})
+	sto2tx.Put([]byte{2}, []byte{8})
+	sto2tx.Put([]byte{3}, []byte{9})
+	assert.Nil(t, sto2tx.Commit())
+
+	r, err := sto1.List(100)
+	assert.Nil(t, err)
+	assert.Equal(t, 3, len(r))
+	assert.Equal(t, r[0], db.KV{[]byte{1}, []byte{4}})
+	assert.Equal(t, r[1], db.KV{[]byte{2}, []byte{5}})
+	assert.Equal(t, r[2], db.KV{[]byte{3}, []byte{6}})
+
+	r, err = sto1.List(2)
+	assert.Nil(t, err)
+	assert.Equal(t, 2, len(r))
+	assert.Equal(t, r[0], db.KV{[]byte{1}, []byte{4}})
+	assert.Equal(t, r[1], db.KV{[]byte{2}, []byte{5}})
+
+}