channeldb/migtest: add migration test tools

This commit adds test helper code to dump, restore and verify the
low-level bbolt database structure.

channeldb/migtest/raw_db.go

@@ -0,0 +1,187 @@
+package migtest
+
+import (
+	"bytes"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/coreos/bbolt"
+)
+
+// DumpDB dumps go code describing the contents of the database to stdout. This
+// function is only intended for use during development.
+//
+// Example output:
+//
+// map[string]interface{}{
+// 	hex("1234"): map[string]interface{}{
+// 		"human-readable": hex("102030"),
+// 		hex("1111"): hex("5783492373"),
+// 	},
+// }
+func DumpDB(tx *bbolt.Tx, rootKey []byte) error {
+	bucket := tx.Bucket(rootKey)
+	if bucket == nil {
+		return fmt.Errorf("bucket %v not found", string(rootKey))
+	}
+
+	return dumpBucket(bucket)
+}
+
+func dumpBucket(bucket *bbolt.Bucket) error {
+	fmt.Printf("map[string]interface{} {\n")
+	err := bucket.ForEach(func(k, v []byte) error {
+		key := toString(k)
+		fmt.Printf("%v: ", key)
+
+		subBucket := bucket.Bucket(k)
+		if subBucket != nil {
+			err := dumpBucket(subBucket)
+			if err != nil {
+				return err
+			}
+		} else {
+			fmt.Print(toHex(v))
+		}
+		fmt.Printf(",\n")
+
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+	fmt.Printf("}")
+
+	return nil
+}
+
+// RestoreDB primes the database with the given data set.
+func RestoreDB(tx *bbolt.Tx, rootKey []byte, data map[string]interface{}) error {
+	bucket, err := tx.CreateBucket(rootKey)
+	if err != nil {
+		return err
+	}
+
+	return restoreDB(bucket, data)
+}
+
+func restoreDB(bucket *bbolt.Bucket, data map[string]interface{}) error {
+	for k, v := range data {
+		key := []byte(k)
+
+		switch value := v.(type) {
+
+		// Key contains value.
+		case string:
+			err := bucket.Put(key, []byte(value))
+			if err != nil {
+				return err
+			}
+
+		// Key contains a sub-bucket.
+		case map[string]interface{}:
+			subBucket, err := bucket.CreateBucket(key)
+			if err != nil {
+				return err
+			}
+
+			if err := restoreDB(subBucket, value); err != nil {
+				return err
+			}
+
+		default:
+			return errors.New("invalid type")
+		}
+	}
+
+	return nil
+}
+
+// VerifyDB verifies the database against the given data set.
+func VerifyDB(tx *bbolt.Tx, rootKey []byte, data map[string]interface{}) error {
+	bucket := tx.Bucket(rootKey)
+	if bucket == nil {
+		return fmt.Errorf("bucket %v not found", string(rootKey))
+	}
+
+	return verifyDB(bucket, data)
+}
+
+func verifyDB(bucket *bbolt.Bucket, data map[string]interface{}) error {
+	for k, v := range data {
+		key := []byte(k)
+
+		switch value := v.(type) {
+
+		// Key contains value.
+		case string:
+			expectedValue := []byte(value)
+			dbValue := bucket.Get(key)
+
+			if !bytes.Equal(dbValue, expectedValue) {
+				return errors.New("value mismatch")
+			}
+
+		// Key contains a sub-bucket.
+		case map[string]interface{}:
+			subBucket := bucket.Bucket(key)
+			if subBucket == nil {
+				return fmt.Errorf("bucket %v not found", k)
+			}
+
+			err := verifyDB(subBucket, value)
+			if err != nil {
+				return err
+			}
+
+		default:
+			return errors.New("invalid type")
+		}
+	}
+
+	keyCount := 0
+	err := bucket.ForEach(func(k, v []byte) error {
+		keyCount++
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+	if keyCount != len(data) {
+		return errors.New("unexpected keys in database")
+	}
+
+	return nil
+}
+
+func toHex(v []byte) string {
+	if len(v) == 0 {
+		return "nil"
+	}
+
+	return "hex(\"" + hex.EncodeToString(v) + "\")"
+}
+
+func toString(v []byte) string {
+	readableChars := "abcdefghijklmnopqrstuvwxyz0123456789-"
+
+	for _, c := range v {
+		if !strings.Contains(readableChars, string(c)) {
+			return toHex(v)
+		}
+	}
+
+	return "\"" + string(v) + "\""
+}
+
+// Hex is a test helper function to convert readable hex arrays to raw byte
+// strings.
+func Hex(value string) string {
+	b, err := hex.DecodeString(value)
+	if err != nil {
+		panic(err)
+	}
+	return string(b)
+}