Database dump script produces a dump with syntax errors in it

I'll see if I can track this down.

This contains a fix, plus an integration test on the dump command, and a unit test on the Variable::export() method.

+++ b/core/modules/system/src/Tests/Update/DbDumpTest.php
@@ -98,15 +99,20 @@ public function setUp() {
 
+    // Create user account with some potential syntax issues.
+    $account = User::create(['mail' => 'q\'uote$dollar@example.com', 'name' => '$dollar']);
+    $account->save();
+
     // Create a cache table (this will create 'cache_discovery').

Should we check the exactly result in the file?

This checks for the exported name and email address in the generated dump.

Great, thank you for the additional test coverage.

And the fun doesn't stop with upgrade path-related issues. :P

Committed and pushed to 8.0.x. Thanks!