Cannot discover test frameworks

[Eason du]

Describe the bug

I got an error while work on cross jvm/js project in Scala 2.13:

Encountered an error in the build server: Cannot discover test frameworks, missing node_modules in test project, expected them at ~/proj/js/node_modules

the error seems to come from

bloop/bridges/scalajs-1/src/main/scala/bloop/scalajs/JsBridge.scala

Line 173 in 04cc096

 s"Cannot discover test frameworks, missing node_modules in test project, expected them at $nodeModules" 

it's a bit confusing about what does discoverTestFrameworks expected to do for js projects?

also at scalameta/metals#5866