See this log from travis-ci, where tests are failed but 0 was returned.
Test "./tests/testphase/article/get.json" failed with message
Expected status code "200" got "0"
Unable to create test from file "./tests/testphase/article/get-byid.json"
With message: "Unset variable "articleId" in testphase Globals"
The command "composer testphase" exited with 0.
See this log from travis-ci, where tests are failed but
0
was returned.