Add processes status stats in system input plugin

plugins/inputs/system/processes_test.go

@@ -0,0 +1,21 @@
+package system
+
+import (
+	"testing"
+
+	"github.com/influxdata/telegraf/testutil"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestProcesses(t *testing.T) {
+	processes := &Processes{}
+	var acc testutil.Accumulator
+
+	err := processes.Gather(&acc)
+	require.NoError(t, err)
+
+	assert.True(t, acc.HasUIntField("processes", "running"))
+	assert.True(t, acc.HasUIntField("processes", "sleeping"))
+	assert.True(t, acc.HasUIntField("processes", "stopped"))
+}