Fix test for windows and darwin

plugins/inputs/procstat/README.md

@@ -81,6 +81,11 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
 Preliminary support for Windows has been added, however you may prefer using
 the `win_perf_counters` input plugin as a more mature alternative.
 
+### Darwin specifics
+
+If you use this plugin with `supervisor_units` *and* `pattern` on Darwin, you
+**have to** use the `pgrep` finder as the underlying library relies on `pgrep`.
+
 ### Permissions
 
 Some files or directories may require elevated permissions. As such a user may

plugins/inputs/procstat/native_finder_test.go

@@ -29,7 +29,7 @@ func BenchmarkFullPattern(b *testing.B) {
 }
 
 func TestChildPattern(t *testing.T) {
-	if runtime.GOOS == "Windows" {
+	if runtime.GOOS == "windows" || runtime.GOOS == "darwin" {
 		t.Skip("Skipping test on unsupported platform")
 	}
 

plugins/inputs/procstat/procstat.go

@@ -4,6 +4,7 @@ package procstat
 import (
 	"bytes"
 	_ "embed"
+	"errors"
 	"fmt"
 	"os"
 	"os/exec"
@@ -22,11 +23,6 @@ import (
 //go:embed sample.conf
 var sampleConfig string
 
-var (
-	defaultPIDFinder = NewPgrep
-	defaultProcess   = NewProc
-)
-
 type PID int32
 
 type Procstat struct {
@@ -65,22 +61,34 @@ func (*Procstat) SampleConfig() string {
 	return sampleConfig
 }
 
-func (p *Procstat) Gather(acc telegraf.Accumulator) error {
-	if p.createPIDFinder == nil {
-		switch p.PidFinder {
-		case "native":
-			p.createPIDFinder = NewNativeFinder
-		case "pgrep":
-			p.createPIDFinder = NewPgrep
-		default:
-			p.PidFinder = "pgrep"
-			p.createPIDFinder = defaultPIDFinder
-		}
+func (p *Procstat) Init() error {
+	if strings.ToLower(p.Mode) == "solaris" {
+		p.solarisMode = true
 	}
-	if p.createProcess == nil {
-		p.createProcess = defaultProcess
+
+	switch p.PidFinder {
+	case "":
+		p.PidFinder = "pgrep"
+		p.createPIDFinder = NewPgrep
+	case "native":
+		p.createPIDFinder = NewNativeFinder
+	case "pgrep":
+		p.createPIDFinder = NewPgrep
+	default:
+		return fmt.Errorf("unknown pid_finder %q", p.PidFinder)
 	}
 
+	// gopsutil relies on pgrep when looking up children on darwin
+	// see https://github.com/shirou/gopsutil/blob/v3.23.10/process/process_darwin.go#L235
+	requiresChildren := len(p.SupervisorUnit) > 0 && p.Pattern != ""
+	if requiresChildren && p.PidFinder == "native" && runtime.GOOS == "darwin" {
+		return errors.New("configuration requires the 'pgrep' finder on you OS")
+	}
+
+	return nil
+}
+
+func (p *Procstat) Gather(acc telegraf.Accumulator) error {
 	pidCount := 0
 	now := time.Now()
 	newProcs := make(map[PID]Process, len(p.procs))
@@ -600,16 +608,8 @@ func (p *Procstat) winServicePIDs() ([]PID, error) {
 	return pids, nil
 }
 
-func (p *Procstat) Init() error {
-	if strings.ToLower(p.Mode) == "solaris" {
-		p.solarisMode = true
-	}
-
-	return nil
-}
-
 func init() {
 	inputs.Add("procstat", func() telegraf.Input {
-		return &Procstat{}
+		return &Procstat{createProcess: NewProc}
 	})
 }

plugins/inputs/procstat/procstat_test.go

@@ -199,6 +199,19 @@ func (p *testProc) Status() ([]string, error) {
 var pid = PID(42)
 var exe = "foo"
 
+func TestInitRequiresChildDarwin(t *testing.T) {
+	if runtime.GOOS != "darwin" {
+		t.Skip("Skipping test on non-darwin platform")
+	}
+
+	p := Procstat{
+		Pattern:        "somepattern",
+		SupervisorUnit: []string{"a_unit"},
+		PidFinder:      "native",
+	}
+	require.ErrorContains(t, p.Init(), "requires the 'pgrep' finder")
+}
+
 func TestGather_CreateProcessErrorOk(t *testing.T) {
 	var acc testutil.Accumulator
 
@@ -433,11 +446,11 @@ func TestGather_cgroupPIDs(t *testing.T) {
 func TestProcstatLookupMetric(t *testing.T) {
 	p := Procstat{
 		createPIDFinder: pidFinder([]PID{543}),
+		createProcess:   NewProc,
 		Exe:             "-Gsys",
 	}
 	var acc testutil.Accumulator
-	err := acc.GatherError(p.Gather)
-	require.NoError(t, err)
+	require.NoError(t, acc.GatherError(p.Gather))
 	require.Len(t, acc.Metrics, len(p.procs)+1)
 }