Ignore devstate when existing process name is not odo + delete devstate files with odo delete component (#7090)

* Ignore devstate when existing process name is not odo

* Delete orphan devstate files with odo delete component

* Update unit tests

* Create fake system

* Add unit tests for odo delete component

* Integration tests for odo dev

* Troubleshooting

* First process on Windows is 4

* Use go-ps lib for pidExists

pkg/odo/cli/delete/component/component.go

@@ -310,9 +310,14 @@ func (o *ComponentOptions) deleteDevfileComponent(ctx context.Context) ([]unstru
 		hasPodmanResources = len(podmanPods) != 0
 	}
 
+	orphans, err := o.getOrphanDevstateFiles(o.clientset.FS, ctx)
+	if err != nil {
+		return nil, err
+	}
+
 	if !(hasClusterResources || hasPodmanResources) {
 		log.Finfof(o.clientset.Stdout, messageWithPlatforms(o.clientset.KubernetesClient != nil, o.clientset.PodmanClient != nil, componentName, namespace))
-		if !o.withFilesFlag {
+		if !o.withFilesFlag && len(orphans) == 0 {
 			// check for resources here
 			return remainingResources, nil
 		}
@@ -326,9 +331,15 @@ func (o *ComponentOptions) deleteDevfileComponent(ctx context.Context) ([]unstru
 		if err != nil {
 			return nil, err
 		}
+	}
+
+	filesToDelete = append(filesToDelete, orphans...)
+
+	hasFilesToDelete := len(filesToDelete) != 0
+
+	if hasFilesToDelete {
 		o.printFileCreatedByOdo(filesToDelete, hasClusterResources)
 	}
-	hasFilesToDelete := len(filesToDelete) != 0
 
 	if !(hasClusterResources || hasPodmanResources || hasFilesToDelete) {
 		klog.V(2).Info("no cluster resources and no files to delete")
@@ -386,7 +397,7 @@ func (o *ComponentOptions) deleteDevfileComponent(ctx context.Context) ([]unstru
 			log.Finfof(o.clientset.Stdout, "The component %q is successfully deleted from podman", componentName)
 		}
 
-		if o.withFilesFlag {
+		if o.withFilesFlag || len(orphans) > 0 {
 			// Delete files
 			remainingFiles := o.deleteFilesCreatedByOdo(o.clientset.FS, filesToDelete)
 			var listOfFiles []string
@@ -495,6 +506,20 @@ func getFilesCreatedByOdo(filesys filesystem.Filesystem, ctx context.Context) ([
 	return list, nil
 }
 
+// getOrphanDevstateFiles gets the list of all Devstate files for which no odo process exists
+func (o *ComponentOptions) getOrphanDevstateFiles(filesys filesystem.Filesystem, ctx context.Context) ([]string, error) {
+	var list []string
+	if o.runningIn != labels.ComponentDeployMode {
+		var orphanDevstates []string
+		orphanDevstates, err := o.clientset.StateClient.GetOrphanFiles(ctx)
+		if err != nil {
+			return nil, err
+		}
+		list = append(list, orphanDevstates...)
+	}
+	return list, nil
+}
+
 func (o *ComponentOptions) printFileCreatedByOdo(files []string, hasClusterResources bool) {
 	if len(files) == 0 {
 		return
@@ -544,7 +569,7 @@ func NewCmdComponent(ctx context.Context, name, fullName string, testClientset c
 	componentCmd.Flags().BoolVarP(&o.withFilesFlag, "files", "", false, "Delete all files and directories generated by odo. Use with caution.")
 	componentCmd.Flags().BoolVarP(&o.forceFlag, "force", "f", false, "Delete component without prompting")
 	componentCmd.Flags().BoolVarP(&o.waitFlag, "wait", "w", false, "Wait for deletion of all dependent resources")
-	clientset.Add(componentCmd, clientset.DELETE_COMPONENT, clientset.KUBERNETES, clientset.FILESYSTEM)
+	clientset.Add(componentCmd, clientset.DELETE_COMPONENT, clientset.KUBERNETES, clientset.FILESYSTEM, clientset.STATE)
 	if feature.IsEnabled(ctx, feature.GenericPlatformFlag) {
 		clientset.Add(componentCmd, clientset.PODMAN_NULLABLE)
 	}

pkg/odo/cli/delete/component/component_test.go

@@ -9,7 +9,6 @@ import (
 	"testing"
 
 	"github.com/devfile/library/v2/pkg/devfile/parser"
-	"github.com/devfile/library/v2/pkg/testingutil/filesystem"
 	"github.com/golang/mock/gomock"
 	"github.com/google/go-cmp/cmp"
 	corev1 "k8s.io/api/core/v1"
@@ -23,7 +22,10 @@ import (
 	odocontext "github.com/redhat-developer/odo/pkg/odo/context"
 	"github.com/redhat-developer/odo/pkg/odo/genericclioptions/clientset"
 	"github.com/redhat-developer/odo/pkg/podman"
+	"github.com/redhat-developer/odo/pkg/state"
 	"github.com/redhat-developer/odo/pkg/testingutil"
+	"github.com/redhat-developer/odo/pkg/testingutil/filesystem"
+	"github.com/redhat-developer/odo/pkg/testingutil/system"
 )
 
 func TestComponentOptions_deleteNamedComponent(t *testing.T) {
@@ -420,6 +422,7 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 		remainingResources []unstructured.Unstructured
 		wantErr            bool
 		deleteClient       func(ctrl *gomock.Controller) _delete.Client
+		stateClient        func(ctrl *gomock.Controller) state.Client
 	}{
 		{
 			name: "deleting a component with access to devfile",
@@ -433,6 +436,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().DeleteResources(resources, false).Return([]unstructured.Unstructured{})
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: true,
 			},
@@ -450,6 +458,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().DeleteResources(resources, false).Return([]unstructured.Unstructured{})
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: true,
 				runningIn: labels.ComponentDevMode,
@@ -468,6 +481,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().DeleteResources(resources, false).Return([]unstructured.Unstructured{})
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: true,
 				runningIn: labels.ComponentDeployMode,
@@ -484,6 +502,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 					Return(resources, nil)
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: true,
 				runningIn: labels.ComponentDeployMode,
@@ -501,6 +524,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().DeleteResources(resources, false).Return(nil)
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: true,
 			},
@@ -513,6 +541,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().ListClusterResourcesToDeleteFromDevfile(gomock.Any(), appName, gomock.Any(), labels.ComponentAnyMode).Return(false, nil, errors.New("some error"))
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: true,
 			},
@@ -525,6 +558,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().ListClusterResourcesToDeleteFromDevfile(gomock.Any(), appName, gomock.Any(), labels.ComponentDevMode).Return(false, nil, errors.New("some error"))
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: true,
 				runningIn: labels.ComponentDevMode,
@@ -538,6 +576,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().ListClusterResourcesToDeleteFromDevfile(gomock.Any(), appName, gomock.Any(), labels.ComponentDeployMode).Return(false, nil, errors.New("some error"))
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: true,
 				runningIn: labels.ComponentDeployMode,
@@ -552,6 +595,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().ListClusterResourcesToDelete(gomock.Any(), gomock.Any(), gomock.Any(), labels.ComponentAnyMode)
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: false,
 			},
@@ -565,6 +613,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().ListClusterResourcesToDelete(gomock.Any(), gomock.Any(), gomock.Any(), labels.ComponentDevMode)
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: false,
 				runningIn: labels.ComponentDevMode,
@@ -579,6 +632,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().ListClusterResourcesToDelete(gomock.Any(), gomock.Any(), gomock.Any(), labels.ComponentDeployMode)
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: false,
 				runningIn: labels.ComponentDeployMode,
@@ -594,6 +652,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().ListClusterResourcesToDelete(gomock.Any(), gomock.Any(), gomock.Any(), labels.ComponentAnyMode)
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: true,
 			},
@@ -608,6 +671,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().ListClusterResourcesToDelete(gomock.Any(), gomock.Any(), gomock.Any(), labels.ComponentDevMode)
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: true,
 				runningIn: labels.ComponentDevMode,
@@ -623,6 +691,11 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 				deleteClient.EXPECT().ListClusterResourcesToDelete(gomock.Any(), gomock.Any(), gomock.Any(), labels.ComponentDeployMode)
 				return deleteClient
 			},
+			stateClient: func(ctrl *gomock.Controller) state.Client {
+				fs := filesystem.NewFakeFs()
+				system := system.Default{}
+				return state.NewStateClient(fs, system)
+			},
 			fields: fields{
 				forceFlag: true,
 				runningIn: labels.ComponentDeployMode,
@@ -640,6 +713,7 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 			ctrl := gomock.NewController(t)
 			kubeClient := prepareKubeClient(ctrl, projectName)
 			deleteClient := tt.deleteClient(ctrl)
+			stateClient := tt.stateClient(ctrl)
 			o := &ComponentOptions{
 				name:      tt.fields.name,
 				forceFlag: tt.fields.forceFlag,
@@ -649,6 +723,7 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 					Stderr:           os.Stderr,
 					KubernetesClient: kubeClient,
 					DeleteClient:     deleteClient,
+					StateClient:      stateClient,
 				},
 			}
 			ctx := odocontext.WithNamespace(context.Background(), projectName)
@@ -656,6 +731,7 @@ func TestComponentOptions_deleteDevfileComponent(t *testing.T) {
 			ctx = odocontext.WithWorkingDirectory(ctx, workingDir)
 			ctx = odocontext.WithComponentName(ctx, compName)
 			ctx = odocontext.WithEffectiveDevfileObj(ctx, &info)
+			ctx = odocontext.WithPID(ctx, 101)
 			remainingResources, err := o.deleteDevfileComponent(ctx)
 			if (err != nil) != tt.wantErr {
 				t.Errorf("deleteDevfileComponent() error = %v, wantErr %v", err, tt.wantErr)

pkg/odo/genericclioptions/clientset/clientset.go

@@ -44,6 +44,7 @@ import (
 	"github.com/redhat-developer/odo/pkg/project"
 	"github.com/redhat-developer/odo/pkg/registry"
 	"github.com/redhat-developer/odo/pkg/testingutil/filesystem"
+	"github.com/redhat-developer/odo/pkg/testingutil/system"
 	"github.com/redhat-developer/odo/pkg/watch"
 )
 
@@ -90,6 +91,8 @@ const (
 	STATE = "DEP_STATE"
 	// SYNC instantiates client for pkg/sync
 	SYNC = "DEP_SYNC"
+	// SYSTEM instantiates client for pkg/testingutil/system
+	SYSTEM = "DEP_SYSTEM"
 	// WATCH instantiates client for pkg/watch
 	WATCH = "DEP_WATCH"
 	/* Add key for new package here */
@@ -122,7 +125,7 @@ var subdeps map[string][]string = map[string][]string{
 	PORT_FORWARD: {KUBERNETES_NULLABLE, EXEC, STATE},
 	PROJECT:      {KUBERNETES},
 	REGISTRY:     {FILESYSTEM, PREFERENCE, KUBERNETES_NULLABLE},
-	STATE:        {FILESYSTEM},
+	STATE:        {FILESYSTEM, SYSTEM},
 	SYNC:         {EXEC},
 	WATCH:        {INFORMER, KUBERNETES_NULLABLE},
 	BINDING:      {PROJECT, KUBERNETES_NULLABLE},
@@ -152,6 +155,7 @@ type Clientset struct {
 	RegistryClient        registry.Client
 	StateClient           state.Client
 	SyncClient            sync.Client
+	systemClient          system.System
 	WatchClient           watch.Client
 	/* Add client by alphabetic order */
 }
@@ -201,6 +205,13 @@ func Fetch(command *cobra.Command, platform string, testClientset Clientset) (*C
 			dep.FS = filesystem.DefaultFs{}
 		}
 	}
+	if isDefined(command, SYSTEM) {
+		if testClientset.systemClient != nil {
+			dep.systemClient = testClientset.systemClient
+		} else {
+			dep.systemClient = system.Default{}
+		}
+	}
 	if isDefined(command, INFORMER) {
 		dep.InformerClient = informer.NewInformerClient()
 	}
@@ -289,7 +300,7 @@ func Fetch(command *cobra.Command, platform string, testClientset Clientset) (*C
 		dep.ProjectClient = project.NewClient(dep.KubernetesClient)
 	}
 	if isDefined(command, STATE) {
-		dep.StateClient = state.NewStateClient(dep.FS)
+		dep.StateClient = state.NewStateClient(dep.FS, dep.systemClient)
 	}
 	if isDefined(command, SYNC) {
 		switch platform {

pkg/state/interface.go

@@ -24,4 +24,6 @@ type Client interface {
 
 	// GetAPIServerPorts returns the port where the API servers are listening, possibly per platform.
 	GetAPIServerPorts(ctx context.Context) ([]api.DevControlPlane, error)
+
+	GetOrphanFiles(ctx context.Context) ([]string, error)
 }

pkg/state/process_unix.go

@@ -1,38 +0,0 @@
-//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
-// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris zos
-
-package state
-
-import (
-	"fmt"
-	"os"
-	"syscall"
-)
-
-func pidExists(pid int) (bool, error) {
-	if pid <= 0 {
-		return false, fmt.Errorf("invalid pid %v", pid)
-	}
-	proc, err := os.FindProcess(pid)
-	if err != nil {
-		return false, nil
-	}
-	err = proc.Signal(syscall.Signal(0))
-	if err == nil {
-		return true, nil
-	}
-	if err.Error() == "os: process already finished" {
-		return false, nil
-	}
-	errno, ok := err.(syscall.Errno)
-	if !ok {
-		return false, err
-	}
-	switch errno {
-	case syscall.ESRCH:
-		return false, nil
-	case syscall.EPERM:
-		return true, nil
-	}
-	return false, err
-}

pkg/state/process_windows.go

@@ -1,17 +0,0 @@
-package state
-
-import (
-	"fmt"
-	"os"
-)
-
-func pidExists(pid int) (bool, error) {
-	if pid <= 0 {
-		return false, fmt.Errorf("invalid pid %v", pid)
-	}
-	_, err := os.FindProcess(pid)
-	if err != nil {
-		return false, nil
-	}
-	return true, nil
-}

pkg/state/state.go

@@ -10,24 +10,30 @@ import (
 	"path/filepath"
 	"regexp"
 
+	"github.com/mitchellh/go-ps"
+	"k8s.io/klog"
+
 	"github.com/redhat-developer/odo/pkg/api"
 	"github.com/redhat-developer/odo/pkg/odo/cli/feature"
 	"github.com/redhat-developer/odo/pkg/odo/commonflags"
 	fcontext "github.com/redhat-developer/odo/pkg/odo/commonflags/context"
 	odocontext "github.com/redhat-developer/odo/pkg/odo/context"
 	"github.com/redhat-developer/odo/pkg/testingutil/filesystem"
+	"github.com/redhat-developer/odo/pkg/testingutil/system"
 )
 
 type State struct {
 	content Content
 	fs      filesystem.Filesystem
+	system  system.System
 }
 
 var _ Client = (*State)(nil)
 
-func NewStateClient(fs filesystem.Filesystem) *State {
+func NewStateClient(fs filesystem.Filesystem, system system.System) *State {
 	return &State{
-		fs: fs,
+		fs:     fs,
+		system: system,
 	}
 }
 
@@ -246,7 +252,7 @@ func (o *State) isFreeOrOwnedBy(pid int) (bool, error) {
 		return true, nil
 	}
 
-	exists, err := pidExists(savedContent.PID)
+	exists, err := o.system.PidExists(savedContent.PID)
 	if err != nil {
 		return false, err
 	}
@@ -292,14 +298,99 @@ func (o *State) checkFirstInPlatform(ctx context.Context) error {
 		if content.PID == pid {
 			continue
 		}
-		exists, err := pidExists(content.PID)
+		exists, err := o.system.PidExists(content.PID)
 		if err != nil {
 			return err
 		}
 		if exists {
+			var process ps.Process
+			process, err = o.system.FindProcess(content.PID)
+			if err != nil {
+				klog.V(4).Infof("process %d exists but is not accessible, ignoring", content.PID)
+				continue
+			}
+			if process.Executable() != "odo" && process.Executable() != "odo.exe" {
+				klog.V(4).Infof("process %d exists but is not odo, ignoring", content.PID)
+				continue
+			}
 			// Process exists => problem
 			return NewErrAlreadyRunningOnPlatform(platform, content.PID)
 		}
 	}
 	return nil
 }
+
+func (o *State) GetOrphanFiles(ctx context.Context) ([]string, error) {
+	var (
+		pid    = odocontext.GetPID(ctx)
+		result []string
+	)
+
+	re := regexp.MustCompile(`^devstate\.?[0-9]*\.json$`)
+	entries, err := o.fs.ReadDir(_dirpath)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			// No file found => no orphan files
+			return nil, nil
+		}
+		return nil, err
+	}
+	for _, entry := range entries {
+		if !re.MatchString(entry.Name()) {
+			continue
+		}
+		filename, err := getFullFilename(entry)
+		if err != nil {
+			return nil, err
+		}
+
+		jsonContent, err := o.fs.ReadFile(filepath.Join(_dirpath, entry.Name()))
+		if err != nil {
+			return nil, err
+		}
+		var content Content
+		// Ignore error, to handle empty file
+		_ = json.Unmarshal(jsonContent, &content)
+
+		if content.PID == pid {
+			continue
+		}
+		if content.PID == 0 {
+			// This is devstate.json with pid=0
+			continue
+		}
+		exists, err := o.system.PidExists(content.PID)
+		if err != nil {
+			return nil, err
+		}
+		if exists {
+			var process ps.Process
+			process, err = o.system.FindProcess(content.PID)
+			if err != nil {
+				klog.V(4).Infof("process %d exists but is not accessible => orphan", content.PID)
+				result = append(result, filename)
+				continue
+			}
+			if process == nil {
+				klog.V(4).Infof("process %d does not exist => orphan", content.PID)
+				result = append(result, filename)
+				continue
+			}
+			if process.Executable() != "odo" && process.Executable() != "odo.exe" {
+				klog.V(4).Infof("process %d exists but is not odo => orphan", content.PID)
+				result = append(result, filename)
+				continue
+			}
+			// Process exists => not orphan
+			klog.V(4).Infof("process %d exists and is odo => not orphan", content.PID)
+			continue
+		}
+		klog.V(4).Infof("process %d does not exist => orphan", content.PID)
+		result = append(result, filename)
+	}
+	return result, nil
+}
+
+func getFullFilename(entry fs.FileInfo) (string, error) {
+	return filepath.Abs(filepath.Join(_dirpath, entry.Name()))
+}

pkg/testingutil/system/default.go

@@ -0,0 +1,24 @@
+package system
+
+import "github.com/mitchellh/go-ps"
+
+type Default struct{}
+
+var _ System = Default{}
+
+func (o Default) FindProcess(pid int) (ps.Process, error) {
+	return ps.FindProcess(pid)
+}
+
+func (o Default) PidExists(pid int) (bool, error) {
+	processes, err := ps.Processes()
+	if err != nil {
+		return false, err
+	}
+	for _, process := range processes {
+		if process.Pid() == pid {
+			return true, nil
+		}
+	}
+	return false, nil
+}

pkg/testingutil/system/fake.go

@@ -0,0 +1,41 @@
+package system
+
+import (
+	"errors"
+
+	"github.com/mitchellh/go-ps"
+)
+
+type Fake struct {
+	ProcessId int
+	ParentId  int
+	// PidTable is a map of pid => executable name of existing processes
+	PidTable map[int]string
+}
+
+func (o Fake) Pid() int {
+	return o.ProcessId
+}
+
+func (o Fake) PPid() int {
+	return o.ParentId
+}
+
+func (o Fake) Executable() string {
+	return o.PidTable[o.ProcessId]
+}
+
+var _ System = Fake{}
+
+func (o Fake) FindProcess(pid int) (ps.Process, error) {
+	if _, found := o.PidTable[pid]; found {
+		o.ProcessId = pid
+		return o, nil
+	}
+	return nil, errors.New("no process found")
+}
+
+func (o Fake) PidExists(pid int) (bool, error) {
+	_, found := o.PidTable[pid]
+	return found, nil
+}

pkg/testingutil/system/system.go

@@ -0,0 +1,8 @@
+package system
+
+import "github.com/mitchellh/go-ps"
+
+type System interface {
+	FindProcess(pid int) (ps.Process, error)
+	PidExists(pid int) (bool, error)
+}