Nuclide debugger with node and babel?
Nuclide currently does not support the new v8 Inspector protocol for debugging. You will need to use --debug flag to debug with Nuclide. Note, however, that the old debugger protocol has been removed from Node.js starting with Node.js 8.0.
PS. You can attach to a running Node.js process with Nuclide debugger just fine - just start your tests with node --debug --debug-brk ... and then attach the debugger from Nuclide. The test process will be stopped at first line, allowing you to resume execution at your own convenience.