add MockEnv as more generic function.

internal/common/common.go

@@ -352,6 +352,16 @@ func HostDev(combineWith ...string) string {
 	return GetEnv("HOST_DEV", "/dev", combineWith...)
 }
 
+// MockEnv set environment variable and return revert function.
+// MockEnv should be used testing only.
+func MockEnv(key string, value string) func() {
+	original := os.Getenv(key)
+	os.Setenv(key, value)
+	return func() {
+		os.Setenv(key, original)
+	}
+}
+
 // getSysctrlEnv sets LC_ALL=C in a list of env vars for use when running
 // sysctl commands (see DoSysctrl).
 func getSysctrlEnv(env []string) []string {

process/process_linux_test.go

@@ -5,9 +5,10 @@ package process
 import (
 	"context"
 	"io/ioutil"
-	"os"
 	"strconv"
 	"testing"
+
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 func Test_fillFromStatusWithContext(t *testing.T) {
@@ -15,10 +16,8 @@ func Test_fillFromStatusWithContext(t *testing.T) {
 	if err != nil {
 		t.Error(err)
 	}
-	original := os.Getenv("HOST_PROC")
+	f := common.MockEnv("HOST_PROC", "testdata/linux")
-	os.Setenv("HOST_PROC", "testdata/linux")
+	defer f()
-	defer os.Setenv("HOST_PROC", original)
-
 	for _, pid := range pids {
 		pid, _ := strconv.ParseInt(pid.Name(), 0, 32)
 		p, _ := NewProcess(int32(pid))

v3/internal/common/common.go

@@ -352,6 +352,16 @@ func HostDev(combineWith ...string) string {
 	return GetEnv("HOST_DEV", "/dev", combineWith...)
 }
 
+// MockEnv set environment variable and return revert function.
+// MockEnv should be used testing only.
+func MockEnv(key string, value string) func() {
+	original := os.Getenv(key)
+	os.Setenv(key, value)
+	return func() {
+		os.Setenv(key, original)
+	}
+}
+
 // getSysctrlEnv sets LC_ALL=C in a list of env vars for use when running
 // sysctl commands (see DoSysctrl).
 func getSysctrlEnv(env []string) []string {

v3/process/process_linux_test.go

@@ -5,9 +5,10 @@ package process
 import (
 	"context"
 	"io/ioutil"
-	"os"
 	"strconv"
 	"testing"
+
+	"github.com/shirou/gopsutil/v3/internal/common"
 )
 
 func Test_fillFromStatusWithContext(t *testing.T) {
@@ -15,10 +16,8 @@ func Test_fillFromStatusWithContext(t *testing.T) {
 	if err != nil {
 		t.Error(err)
 	}
-	original := os.Getenv("HOST_PROC")
+	f := common.MockEnv("HOST_PROC", "testdata/linux")
-	os.Setenv("HOST_PROC", "testdata/linux")
+	defer f()
-	defer os.Setenv("HOST_PROC", original)
-
 	for _, pid := range pids {
 		pid, _ := strconv.ParseInt(pid.Name(), 0, 32)
 		p, _ := NewProcess(int32(pid))