lib/trie: add Version type (#2736)

- `String()` method
- `ParseVersion` function

lib/trie/version.go

@@ -0,0 +1,44 @@
+// Copyright 2022 ChainSafe Systems (ON)
+// SPDX-License-Identifier: LGPL-3.0-only
+
+package trie
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+)
+
+// Version is the state trie version which dictates how a
+// Merkle root should be constructed. It is defined in
+// https://spec.polkadot.network/#defn-state-version
+type Version uint8
+
+const (
+	// V0 is the state trie version 0 where the values of the keys are
+	// inserted into the trie directly.
+	// TODO set to iota once CI passes
+	V0 Version = 1
+)
+
+func (v Version) String() string {
+	switch v {
+	case V0:
+		return "v0"
+	default:
+		panic(fmt.Sprintf("unknown version %d", v))
+	}
+}
+
+var ErrParseVersion = errors.New("parsing version failed")
+
+// ParseVersion parses a state trie version string.
+func ParseVersion(s string) (version Version, err error) {
+	switch {
+	case strings.EqualFold(s, V0.String()):
+		return V0, nil
+	default:
+		return version, fmt.Errorf("%w: %q must be %s",
+			ErrParseVersion, s, V0)
+	}
+}

lib/trie/version_test.go

@@ -0,0 +1,86 @@
+// Copyright 2022 ChainSafe Systems (ON)
+// SPDX-License-Identifier: LGPL-3.0-only
+
+package trie
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_Version_String(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		version       Version
+		versionString string
+		panicMessage  string
+	}{
+		"v0": {
+			version:       V0,
+			versionString: "v0",
+		},
+		"invalid": {
+			version:      Version(99),
+			panicMessage: "unknown version 99",
+		},
+	}
+
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			if testCase.panicMessage != "" {
+				assert.PanicsWithValue(t, testCase.panicMessage, func() {
+					_ = testCase.version.String()
+				})
+				return
+			}
+
+			versionString := testCase.version.String()
+			assert.Equal(t, testCase.versionString, versionString)
+		})
+	}
+}
+
+func Test_ParseVersion(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		s          string
+		version    Version
+		errWrapped error
+		errMessage string
+	}{
+		"v0": {
+			s:       "v0",
+			version: V0,
+		},
+		"V0": {
+			s:       "V0",
+			version: V0,
+		},
+		"invalid": {
+			s:          "xyz",
+			errWrapped: ErrParseVersion,
+			errMessage: "parsing version failed: \"xyz\" must be v0",
+		},
+	}
+
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			version, err := ParseVersion(testCase.s)
+
+			assert.Equal(t, testCase.version, version)
+			assert.ErrorIs(t, err, testCase.errWrapped)
+			if testCase.errWrapped != nil {
+				assert.EqualError(t, err, testCase.errMessage)
+			}
+		})
+	}
+}