Using tsc version 2.9.2 Ganache CLI v6.1.3 (ganache-core: 2.1.2) Node v10.5.0 npm 6.1.0
Run npm install and then npm run test and run ganache with ganache-cli -p 9545. You need typescript installed on your machine but everything else is local.
To fix it, change the dummy member in Dummy.sol to private and there is no issue.
Change it to public and there is an issue.
Change it to internal and there is no issue.