Add automatic tests to the project

[krufab]

Added tests to the project, as per issue jenkinsci/docker-agent#671 and issue 100 in docker-slave

Closes jenkinsci/docker-agent#671

[oleg-nenashev]

Thanks! We will need to resubmit the PR to check whether the Jenkinsfile really works on the CI instance, but the code looks good overall

[krufab]

Please note that the tests are not being executed as the modified Jenkinsfile isn't processed. Besides, I guess bats won't be available on the machine..

[slide]

I created #143 to test the build

[krufab]

Is it ok this PR or is there anything to change?

[oleg-nenashev]

Looks great, thanks!

[oleg-nenashev]

Ignoring the CI issues, because Windows infra needs a fix

[oleg-nenashev]

@slide @krufab Looks like CI fails after all

[2020-01-29T16:39:16.098Z] + make test

[2020-01-29T16:39:16.098Z] Cloning into 'bats-core'...

[2020-01-29T16:39:16.356Z] HEAD is now at c706d14 Bats 1.1.0

[2020-01-29T16:39:20.528Z] 1..4

[2020-01-29T16:39:20.784Z] ok 1 [alpine] build image

[2020-01-29T16:39:24.964Z] ok 2 [alpine] image has installed jenkins-agent in PATH

[2020-01-29T16:39:39.824Z] ok 3 [alpine] image starts jenkins-agent correctly

[2020-01-29T16:39:58.494Z] ok 4 [alpine] use build args correctly

[2020-01-29T16:39:58.494Z] 1..4

[2020-01-29T16:39:58.494Z] ok 1 [debian] build image

[2020-01-29T16:40:01.027Z] ok 2 [debian] image has installed jenkins-agent in PATH

[2020-01-29T16:40:15.882Z] not ok 3 [debian] image starts jenkins-agent correctly

[2020-01-29T16:40:15.882Z] # (in test file tests/tests.bats, line 59)

[2020-01-29T16:40:15.882Z] #   `[ $'GET /tcpSlaveAgentListener/ HTTP/1.1\r' = "${lines[0]}" ]' failed with status 124

[2020-01-29T16:40:15.882Z] # 1e24fe7e97e28d951d3da2c5e844409ac5330aa373f65d9b7aecc6d2b0c96ef9

[2020-01-29T16:40:15.882Z] # 9242597faa79c429ab5d8ea96714926472644b887b3add40a799a2984432cd68

[2020-01-29T16:40:15.882Z] # /tmp/bats.25649.src: line 59: lines[0]: unbound variable

[2020-01-29T16:41:02.522Z] ok 4 [debian] use build args correctly

[2020-01-29T16:41:02.522Z] Makefile:33: recipe for target 'test-debian' failed

[2020-01-29T16:41:02.522Z] make: *** [test-debian] Error 1

[krufab]

I'll check it in few hours

[krufab]

The failure is probably due to the fact that it took too much time to start the jenkins jnlp agent image. Test 3 completes successfully for alpine and it's the same code for the debian one.
The test firstly spins off a docker jnlp agent in a detached mode, then starts a netcat container listening on port 5000 which waits for 10s to have the agent connect. After 10s the netcat container shuts down and returns the header read (if any). If the jnlp container doesn't boot it that time, the test fails.

To fix it, we can extend the timeout to i.e. 30s. I can create a branch to patch master or I can resolve the issue in the next full change branch that I will submit soon.

[oleg-nenashev]

Small change for this issue would be great

[krufab]

Done in #148