val mockTheClient = mock[TheClient]
val testMyClient = new MyClient()
testMyClient.client = mockTheClient
testMyClient.getSomethingFromTheClient() shouldBe "blabla"

class MyClient(client: TheClient = new TheClient()) {
  def getSomethingFromTheClient() = {
    client.getSomething() + " from MyClient"
  }
}

val mockTheClient = mock[TheClient]
val testMyClient = new MyClient(mockTheClient)
testMyClient.getSomethingFromTheClient() shouldBe "blabla"