abstract from sql.DB vs sql.Tx

Now we can use get_user/get_otp without having to open a transaction
each time (which also fixes a leak of transactions if an error occurs).

goatherd.go

@@ -92,6 +92,13 @@ func get_line(reader *bufio.Reader) (string, error) {
 }
 
 
+type db_conn interface {
+    Exec(query string, args ...interface{}) (sql.Result, error)
+    QueryRow(query string, args ...interface{}) *sql.Row
+    Prepare(query string) (*sql.Stmt, error)
+}
+
+
 func create_table(db *sql.DB) {
     debug("Creating table 'users' in DB")
 
@@ -134,11 +141,11 @@ func create_user(db *sql.DB, name string, secret_b64 string) {
 
 
 
-func get_user(tx *sql.Tx, name string) (secret []byte, count uint64, err error) {
-    stmt, err := tx.Prepare("SELECT secret, count FROM users WHERE name = ?")
-    if transaction_failed(err) {
+func get_user(db db_conn, name string) (secret []byte, count uint64, err error) {
+    stmt, err := db.Prepare("SELECT secret, count FROM users WHERE name = ?")
+    if err != nil {
         return
-    } else { err_panic(err) }
+    }
 
     err = stmt.QueryRow(name).Scan(&secret, &count)
     stmt.Close()
@@ -146,19 +153,19 @@ func get_user(tx *sql.Tx, name string) (secret []byte, count uint64, err error)
     return
 }
 
-func set_count(tx *sql.Tx, name string, count uint64) error {
-    inc, err := tx.Prepare("UPDATE users SET count = ? WHERE name = ?")
-    if transaction_failed(err) {
+func set_count(db db_conn, name string, count uint64) error {
+    inc, err := db.Prepare("UPDATE users SET count = ? WHERE name = ?")
+    if err != nil {
         return err
-    } else { err_panic(err) }
+    }
 
     _, err = inc.Exec(count, name)
     inc.Close()
     return err
 }
 
-func get_otp(tx *sql.Tx, name string) (*hotp.HOTP, error) {
-    secret, count, err := get_user(tx, name)
+func get_otp(db db_conn, name string) (*hotp.HOTP, error) {
+    secret, count, err := get_user(db, name)
     if err != nil { return nil, err }
 
     return hotp.NewHOTP(secret, count, 6), nil

goatherd_test.go

@@ -40,11 +40,9 @@ func create_and_check(user string, sec string) func(*testing.T) {
         }
 
         t.Run("exists", func(t *testing.T) {
-            tx, err := db.Begin()
+            var err error
+            result.secret, result.count, err = get_user(db, username)
             t_err_fatal(t, err)
-            result.secret, result.count, err = get_user(tx, username)
-            t_err_fatal(t, err)
-            tx.Commit()
         })
 
         t.Run("correct_secret", func(t *testing.T) {
@@ -108,11 +106,8 @@ func check_offer_t(t *testing.T) {
         if err != sql.ErrNoRows { t.Error("err:", nil) }
     })
 
-    tx, err := db.Begin()
-    t_err_fatal(t, err)
-    secret, count, err := get_user(tx, username)
+    secret, count, err := get_user(db, username)
     t_err_fatal(t, err)
-    tx.Commit()
 
     t.Run("fail", func(t *testing.T) {
         ok, err := check_offer(db, "mock", username, "dummy offer")
@@ -213,11 +208,8 @@ func handle_conn_t(t *testing.T) {
         }
     })
 
-    tx, err := db.Begin()
-    t_err_fatal(t, err)
-    otp, err := get_otp(tx, username)
+    otp, err := get_otp(db, username)
     t_err_fatal(t, err)
-    tx.Commit()
 
     t.Run("ok", func(t *testing.T) {
         recv := make(chan string)