Ensures that archiver extensions are properly merged in the UI.
function testFileNameExtensionMerging() {
$this
->drupalGet('admin/modules/install');
// Make sure the bogus extension supported by update_test.module is there.
$this
->assertPattern('/file extensions are supported:.*update-test-extension/', "Found 'update-test-extension' extension");
// Make sure it didn't clobber the first option from core.
$this
->assertPattern('/file extensions are supported:.*tar/', "Found 'tar' extension");
}