Add process telemetry tests and avoid frequent error on Windows (#1487)

* Add process telemetry tests

* Get the procfs.Proc instance at creation, this avoids failing constantly on Windows.

internal/collector/telemetry/process_telemetry.go

@@ -30,6 +30,7 @@ type ProcessMetricsViews struct {
 	ballastSizeBytes uint64
 	views            []*view.View
 	done             chan struct{}
+	proc             *procfs.Proc
 }
 
 var mRuntimeAllocMem = stats.Int64(
@@ -83,17 +84,27 @@ var viewCPUSeconds = &view.View{
 // NewProcessMetricsViews creates a new set of ProcessMetrics (mem, cpu) that can be used to measure
 // basic information about this process.
 func NewProcessMetricsViews(ballastSizeBytes uint64) *ProcessMetricsViews {
-	return &ProcessMetricsViews{
+	pmv := &ProcessMetricsViews{
 		ballastSizeBytes: ballastSizeBytes,
 		views:            []*view.View{viewAllocMem, viewTotalAllocMem, viewSysMem, viewCPUSeconds},
 		done:             make(chan struct{}),
 	}
+
+	// procfs.Proc is not available on windows and expected to fail.
+	pid := os.Getpid()
+	proc, err := procfs.NewProc(pid)
+	if err == nil {
+		pmv.proc = &proc
+	}
+
+	return pmv
 }
 
 // StartCollection starts a ticker'd goroutine that will update the PMV measurements every 5 seconds
 func (pmv *ProcessMetricsViews) StartCollection() {
-	ticker := time.NewTicker(5 * time.Second)
 	go func() {
+		ticker := time.NewTicker(5 * time.Second)
+		defer ticker.Stop()
 		for {
 			select {
 			case <-ticker.C:
@@ -105,12 +116,12 @@ func (pmv *ProcessMetricsViews) StartCollection() {
 	}()
 }
 
-// Views returns the views internal to the PMV
+// Views returns the views internal to the PMV.
 func (pmv *ProcessMetricsViews) Views() []*view.View {
 	return pmv.views
 }
 
-// StopCollection stops the collection of the process metric information
+// StopCollection stops the collection of the process metric information.
 func (pmv *ProcessMetricsViews) StopCollection() {
 	close(pmv.done)
 }
@@ -122,10 +133,8 @@ func (pmv *ProcessMetricsViews) updateViews() {
 	stats.Record(context.Background(), mRuntimeTotalAllocMem.M(int64(ms.TotalAlloc)))
 	stats.Record(context.Background(), mRuntimeSysMem.M(int64(ms.Sys)))
 
-	pid := os.Getpid()
-	proc, err := procfs.NewProc(pid)
-	if err == nil {
-		if procStat, err := proc.Stat(); err == nil {
+	if pmv.proc != nil {
+		if procStat, err := pmv.proc.Stat(); err == nil {
 			stats.Record(context.Background(), mCPUSeconds.M(int64(procStat.CPUTime())))
 		}
 	}

internal/collector/telemetry/process_telemetry_test.go

@@ -0,0 +1,73 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package telemetry
+
+import (
+	"runtime"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.opencensus.io/stats/view"
+)
+
+func TestProcessTelemetry(t *testing.T) {
+	const ballastSizeBytes uint64 = 0
+
+	pmv := NewProcessMetricsViews(ballastSizeBytes)
+	assert.NotNil(t, pmv)
+
+	expectedViews := []string{
+		// Changing a metric name is a breaking change.
+		// Adding new metrics is ok as long it follows the conventions described at
+		// https://pkg.go.dev/go.opentelemetry.io/collector/obsreport?tab=doc#hdr-Naming_Convention_for_New_Metrics
+		"process/runtime/heap_alloc_bytes",
+		"process/runtime/total_alloc_bytes",
+		"process/runtime/total_sys_memory_bytes",
+		"process/cpu_seconds",
+	}
+	processViews := pmv.Views()
+	assert.Len(t, processViews, len(expectedViews))
+
+	require.NoError(t, view.Register(processViews...))
+	defer view.Unregister(processViews...)
+
+	// Check that the views are actually filled.
+	pmv.updateViews()
+	<-time.After(200 * time.Millisecond)
+
+	for _, viewName := range expectedViews {
+		if runtime.GOOS == "windows" && viewName == "process/cpu_seconds" {
+			continue
+		}
+
+		rows, err := view.RetrieveData(viewName)
+		require.NoError(t, err, viewName)
+
+		require.Len(t, rows, 1, viewName)
+		row := rows[0]
+		assert.Len(t, row.Tags, 0)
+
+		lastValue := row.Data.(*view.LastValueData)
+		if viewName == "process/cpu_seconds" {
+			// This likely will still be zero when running the test.
+			assert.True(t, lastValue.Value >= 0, viewName)
+			continue
+		}
+
+		assert.True(t, lastValue.Value > 0, viewName)
+	}
+}