dcrsqlite: create DB-file parent directory when necessary (decred#516)

* dcrsqlite: add test to reproduce the issue decred#515

decred#515

* dcrsqlite: create DB-file parent directory when necessary

Fixes decred#515

* dcrsqlite: move test helpers to a testutil package

* testutil functions take *testing.T (#1)

.gitignore

@@ -31,3 +31,4 @@ ffldb_stake*/
 *.pprof
 testnet/
 .DS_Store
+testdata/

db/dcrsqlite/.gitignore

@@ -0,0 +1 @@
+test.data

db/dcrsqlite/dcrsqlite_test.go

@@ -0,0 +1,25 @@
+package dcrsqlite
+
+import (
+	"testing"
+
+	"github.com/decred/dcrdata/testutil"
+)
+
+// TestMissingParentFolder ensures InitDB() is able to create a new DB-file parent directory if necessary
+// See https://github.com/decred/dcrdata/issues/515
+func TestMissingParentFolder(t *testing.T) {
+	// Specify DB file in non-existent path
+	testutil.ResetTempFolder(t)
+	targetDBFile := testutil.FilePathInsideTempDir(t, "x/y/z/"+testutil.DefaultDBFileName)
+
+	dbInfo := &DBInfo{FileName: targetDBFile}
+	db, err := InitDB(dbInfo)
+	if err != nil {
+		t.Fatalf("InitDB() failed: %v", err)
+	}
+
+	if db == nil {
+		t.Fatalf("InitDB() failed")
+	}
+}

db/dcrsqlite/sqlite.go

@@ -6,15 +6,16 @@ package dcrsqlite
 import (
 	"database/sql"
 	"fmt"
+	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
 	"sync"
 
-	"github.com/decred/slog"
-
 	"github.com/decred/dcrd/wire"
 	apitypes "github.com/decred/dcrdata/api/types"
 	"github.com/decred/dcrdata/blockdata"
+	"github.com/decred/slog"
 	_ "github.com/mattn/go-sqlite3" // register sqlite driver with database/sql
 )
 
@@ -146,7 +147,19 @@ func NewDB(db *sql.DB) (*DB, error) {
 // InitDB creates a new DB instance from a DBInfo containing the name of the
 // file used to back the underlying sql database.
 func InitDB(dbInfo *DBInfo) (*DB, error) {
-	db, err := sql.Open("sqlite3", dbInfo.FileName)
+	dbPath, err := filepath.Abs(dbInfo.FileName)
+	if err != nil {
+		return nil, err
+	}
+
+	// Ensures target DB-file has a parent folder
+	parent := filepath.Dir(dbPath)
+	err = os.MkdirAll(parent, 0755)
+	if err != nil {
+		return nil, err
+	}
+
+	db, err := sql.Open("sqlite3", dbPath)
 	if err != nil || db == nil {
 		return nil, err
 	}

stakedb/stakedb.go

@@ -399,7 +399,6 @@ func (db *StakeDatabase) ConnectBlock(block *dcrutil.Block) error {
 
 func (db *StakeDatabase) connectBlock(block *dcrutil.Block, spent []chainhash.Hash,
 	revoked []chainhash.Hash, maturing []chainhash.Hash) error {
-
 	hB, err := block.BlockHeaderBytes()
 	if err != nil {
 		return fmt.Errorf("unable to serialize block header: %v", err)

testutil/tempfiles.go

@@ -0,0 +1,45 @@
+// package testutil provides some helper functions to be used in unit tests.
+package testutil
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+const (
+	DefaultDataDirname = "test.data"
+	DefaultDBFileName  = "test.dcrdata.sqlt.db"
+)
+
+// TempFolderPath returns path of a temporary directory used by these tests to
+// store data.
+func TempFolderPath(t *testing.T) string {
+	testDir, err := filepath.Abs(DefaultDataDirname)
+	if err != nil {
+		t.Fatalf("Failed to produce DB-test folder path")
+	}
+	return testDir
+}
+
+// Ensures we run our test in a clean room. Removes all files created by any of
+// these tests in the temp directory.
+func ResetTempFolder(t *testing.T) {
+	testFolderPath := TempFolderPath(t)
+	err := os.RemoveAll(testFolderPath)
+	// Failed to clear test-files
+	if err != nil {
+		t.Fatalf("Failed to clear temp folder")
+	}
+}
+
+// FilePathInsideTempDir creates a path to a file inside the temp directory.
+func FilePathInsideTempDir(t *testing.T, pathInsideTempFolder string) string {
+	tempDir := TempFolderPath(t)
+	targetPath := filepath.Join(tempDir, pathInsideTempFolder)
+	targetPath, err := filepath.Abs(targetPath)
+	if err != nil {
+		t.Fatalf("Failed to build a path: " + pathInsideTempFolder)
+	}
+	return targetPath
+}