Support mkdir -p behavior when DB file does not exist (#180)

Currently, if you supply a DB path that includes directories which
do not exist, sqlite3 will not attempt to create them and the open
will crash.

This adds a quick attempt to `mkdir` on the db path to ensure all intermediary
directories exist before attempting to create the DB file for cases that
`SQLITE_OPEN_CREATE` flag is enabled and would expect the file to be
created when non-existant

lib/exqlite/connection.ex

@@ -389,7 +389,8 @@ defmodule Exqlite.Connection do
   end
 
   defp do_connect(path, options) do
-    with {:ok, db} <- Sqlite3.open(path),
+    with :ok <- mkdir_p(path),
+         {:ok, db} <- Sqlite3.open(path),
          :ok <- set_journal_mode(db, options),
          :ok <- set_temp_store(db, options),
          :ok <- set_synchronous(db, options),
@@ -549,4 +550,11 @@ defmodule Exqlite.Connection do
         {:disconnect, %Error{message: reason, statement: statement}, state}
     end
   end
+
+  # SQLITE_OPEN_CREATE will create the DB file if not existing, but
+  # will not create intermediary directories if they are missing.
+  # So let's preemptively create the intermediate directories here
+  # before trying to open the DB file.
+  defp mkdir_p(":memory:"), do: :ok
+  defp mkdir_p(path), do: File.mkdir_p(Path.dirname(path))
 end

test/exqlite/sqlite3_test.exs

@@ -18,6 +18,15 @@ defmodule Exqlite.Sqlite3Test do
 
       File.rm(path)
     end
+
+    test "creates database path on disk when non-existant" do
+      {:ok, path} = Temp.mkdir()
+      {:ok, conn} = Sqlite3.open(path <> "/non_exist.db")
+
+      assert conn
+
+      File.rm(path)
+    end
   end
 
   describe ".close/2" do