Add tests and end-to-end tests for websocket execution

For unit tests, this mocks the runners Execute method with a
customizable function that operates on the request, streams and exit
channel to simulate a real execution.

End-to-end tests are moved to the tests/e2e_tests folder. The tests
folder allows us to have shared helper functions for all tests in a
separate package (tests) that is not included in the non-test build.

This also adds one second of delay before each end-to-end test case by
using the TestSetup method of suite. By slowing down test execution,
this gives Nomad time to create new allocations when a test requested a
runner. Another solution could be to increase the scale of the job to
have enough allocations for all end-to-end tests.

Co-authored-by: Maximilian Paß <maximilian.pass@student.hpi.uni-potsdam.de>

tests/e2e/health_test.go

@@ -0,0 +1,16 @@
+package e2e
+
+import (
+	"github.com/stretchr/testify/assert"
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/api"
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/tests/e2e/helpers"
+	"net/http"
+	"testing"
+)
+
+func TestHealthRoute(t *testing.T) {
+	resp, err := http.Get(helpers.BuildURL(api.RouteBase, api.RouteHealth))
+	if assert.NoError(t, err) {
+		assert.Equal(t, http.StatusNoContent, resp.StatusCode, "The response code should be NoContent")
+	}
+}