Support Go execd plugins with shim (#7283)

plugins/inputs/execd/shim/shim_test.go

@@ -0,0 +1,119 @@
+package shim
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/influxdata/telegraf"
+)
+
+func TestShimWorks(t *testing.T) {
+	stdoutBytes := bytes.NewBufferString("")
+	stdout = stdoutBytes
+
+	timeout := time.NewTimer(10 * time.Second)
+	wait := runInputPlugin(t, 10*time.Millisecond)
+
+	select {
+	case <-wait:
+	case <-timeout.C:
+		require.Fail(t, "Timeout waiting for metric to arrive")
+	}
+	for stdoutBytes.Len() == 0 {
+		select {
+		case <-timeout.C:
+			require.Fail(t, "Timeout waiting to read metric from stdout")
+			return
+		default:
+			time.Sleep(10 * time.Millisecond)
+		}
+	}
+
+	out := string(stdoutBytes.Bytes())
+	require.Contains(t, out, "\n")
+	metricLine := strings.Split(out, "\n")[0]
+	require.Equal(t, "measurement,tag=tag field=1i 1234000005678", metricLine)
+}
+
+func TestShimStdinSignalingWorks(t *testing.T) {
+	stdoutBytes := bytes.NewBufferString("")
+	stdout = stdoutBytes
+	stdinBytes := bytes.NewBufferString("")
+	stdin = stdinBytes
+
+	timeout := time.NewTimer(10 * time.Second)
+	wait := runInputPlugin(t, 40*time.Second)
+
+	stdinBytes.WriteString("\n")
+
+	select {
+	case <-wait:
+	case <-timeout.C:
+		require.Fail(t, "Timeout waiting for metric to arrive")
+	}
+
+	for stdoutBytes.Len() == 0 {
+		select {
+		case <-timeout.C:
+			require.Fail(t, "Timeout waiting to read metric from stdout")
+			return
+		default:
+			time.Sleep(10 * time.Millisecond)
+		}
+	}
+
+	out := string(stdoutBytes.Bytes())
+	require.Contains(t, out, "\n")
+	metricLine := strings.Split(out, "\n")[0]
+	require.Equal(t, "measurement,tag=tag field=1i 1234000005678", metricLine)
+}
+
+func runInputPlugin(t *testing.T, timeout time.Duration) chan bool {
+	wait := make(chan bool)
+	inp := &testInput{
+		wait: wait,
+	}
+
+	shim := New()
+	shim.AddInput(inp)
+	go func() {
+		err := shim.Run(timeout) // we aren't using the timer here
+		require.NoError(t, err)
+	}()
+	return wait
+}
+
+type testInput struct {
+	wait chan bool
+}
+
+func (i *testInput) SampleConfig() string {
+	return ""
+}
+
+func (i *testInput) Description() string {
+	return ""
+}
+
+func (i *testInput) Gather(acc telegraf.Accumulator) error {
+	acc.AddFields("measurement",
+		map[string]interface{}{
+			"field": 1,
+		},
+		map[string]string{
+			"tag": "tag",
+		}, time.Unix(1234, 5678))
+	i.wait <- true
+	return nil
+}
+
+func (i *testInput) Start(acc telegraf.Accumulator) error {
+	return nil
+}
+
+func (i *testInput) Stop() {
+}