Add tests for dataflow API.

4 jobs from dataflow in 4 minutes 4 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #3252
build_cmake

00:43

 
  Test
passed #3253
run_tests

00:46

 
  Sanitizer
passed #3255
run_address_sanitizer

01:34

passed #3254
run_thread_sanitizer

01:00