// +build linux package chrony import ( "fmt" "os" "os/exec" "testing" "github.com/influxdata/telegraf/testutil" ) func TestGather(t *testing.T) { c := Chrony{ path: "chronyc", } // overwriting exec commands with mock commands execCommand = fakeExecCommand defer func() { execCommand = exec.Command }() var acc testutil.Accumulator err := c.Gather(&acc) if err != nil { t.Fatal(err) } tags := map[string]string{ "reference_id": "192.168.1.22", "leap_status": "normal", "stratum": "3", } fields := map[string]interface{}{ "last_offset": 0.000012651, "rms_offset": 0.000025577, "frequency": -16.001, "residual_freq": 0.0, "skew": 0.006, "root_delay": 0.001655, "root_dispersion": 0.003307, "update_interval": 507.2, } acc.AssertContainsTaggedFields(t, "chrony", fields, tags) } // fackeExecCommand is a helper function that mock // the exec.Command call (and call the test binary) func fakeExecCommand(command string, args ...string) *exec.Cmd { cs := []string{"-test.run=TestHelperProcess", "--", command} cs = append(cs, args...) cmd := exec.Command(os.Args[0], cs...) cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1"} return cmd } // TestHelperProcess isn't a real test. It's used to mock exec.Command // For example, if you run: // GO_WANT_HELPER_PROCESS=1 go test -test.run=TestHelperProcess -- chrony tracking // it returns below mockData. func TestHelperProcess(t *testing.T) { if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" { return } mockData := `Reference ID : 192.168.1.22 (ntp.example.com) Stratum : 3 Ref time (UTC) : Thu May 12 14:27:07 2016 System time : 0.000020390 seconds fast of NTP time Last offset : +0.000012651 seconds RMS offset : 0.000025577 seconds Frequency : 16.001 ppm slow Residual freq : -0.000 ppm Skew : 0.006 ppm Root delay : 0.001655 seconds Root dispersion : 0.003307 seconds Update interval : 507.2 seconds Leap status : Normal ` args := os.Args // Previous arguments are tests stuff, that looks like : // /tmp/go-build970079519/…/_test/integration.test -test.run=TestHelperProcess -- cmd, args := args[3], args[4:] if cmd == "chronyc" && args[0] == "tracking" { fmt.Fprint(os.Stdout, mockData) } else { fmt.Fprint(os.Stdout, "command not found") os.Exit(1) } os.Exit(0) }