public function test_remove_meta_box() {
    global $wp_meta_boxes;

    // Add a meta box to remove.
    add_meta_box( 'testbox1', 'Test Metabox', '__return_false', $current_screen = 'post' );

    // Confirm it's there.
    $this->assertArrayHasKey( 'testbox1', $wp_meta_boxes[ $current_screen ]['advanced']['default'] );

    // Remove the meta box.
    remove_meta_box( 'testbox1', $current_screen, 'advanced' );

    // Check that it was removed properly (the meta box should be set to false once that it has been removed).
    $this->assertFalse( $wp_meta_boxes[ $current_screen ]['advanced']['default']['testbox1'] );
  }