Tests run concurrently within a `TestSuite` on Scala.js

[armanbilge]

//> using dep com.lihaoyi::utest::0.8.4
//> using platform js

import utest._
import scala.concurrent._

object Demo extends TestSuite {
  def tests = Tests {
    test("foo") {
      println("foo started")
      Future(println("foo ended"))(ExecutionContext.global)
    }
    test("bar") {
      println("bar started")
      println("bar ended")
    }
  }
}

-------------------------------- Running Tests --------------------------------
foo started
bar started
bar ended
+ Demo.bar 0ms  
foo ended
+ Demo.foo 58ms  
Tests: 2, Passed: 2, Failed: 0

---

This is problematic when testing React applications using act:

Warning: You seem to have overlapping act() calls, this is not supported. Be sure to await previous act() calls before making a new one.