lib/db: Add Badger backend (fixes #5910) (#6250)

lib/db/backend/badger_test.go

@@ -0,0 +1,38 @@
+// Copyright (C) 2019 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package backend
+
+import "testing"
+
+func TestCommonPrefix(t *testing.T) {
+	cases := []struct {
+		a      string
+		b      string
+		common string
+	}{
+		{"", "", ""},
+		{"a", "b", ""},
+		{"aa", "ab", "a"},
+		{"aa", "a", "a"},
+		{"a", "aa", "a"},
+		{"aabab", "ab", "a"},
+		{"ab", "aabab", "a"},
+		{"abac", "ababab", "aba"},
+		{"ababab", "abac", "aba"},
+	}
+
+	for _, tc := range cases {
+		pref := string(commonPrefix([]byte(tc.a), []byte(tc.b)))
+		if pref != tc.common {
+			t.Errorf("commonPrefix(%q, %q) => %q, expected %q", tc.a, tc.b, pref, tc.common)
+		}
+	}
+}
+
+func TestBadgerBackendBehavior(t *testing.T) {
+	testBackendBehavior(t, OpenBadgerMemory)
+}