Assisn a page template upon plugin activation

I have created a plugin which I include to create a page upon activation.

How do I assign a page-template to the page which the page template is in plugin.

I tried

$testpage = array(
  'ID' => '100', //Are you updating an existing post?
  'page_template' => plugins_url( '/test.php', __FILE__ ), //Sets the template for the page.
  'comment_status' => 'closed', // 'closed' means no comments.
  'post_author' => '1', //The user ID number of the author.
  'post_name' => 'test', // The name (slug) for your post
  'post_status' => 'publish', //Set the status of the new post.
  'post_title' => 'Test Page',//The title of your post.
  'post_type' => 'page', //Sometimes you want to post a page.
);

which test.php is the page template file.