internal/app/dispatcher: reduce check code duplication

This also improves readability of test cases.

Signed-off-by: Ophestra <cat@gensokyo.uk>

5 files changed, 141 insertions, 137 deletions

diff --git a/internal/app/dispatcher_test.go b/internal/app/dispatcher_test.go
index d00170ad..2dd9c882 100644
--- a/internal/app/dispatcher_test.go
+++ b/internal/app/dispatcher_test.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"io/fs"
 	"log"
+	"maps"
 	"os"
 	"os/exec"
 	"reflect"
@@ -26,30 +27,97 @@ func call(name string, args stub.ExpectArgs, ret any, err error) stub.Call {
 	return stub.Call{Name: name, Args: args, Ret: ret, Err: err}
 }
 
-// checkExpectUid is the uid value used by checkOpBehaviour to initialise [system.I].
-const checkExpectUid = 0xcafebabe
-
-// wantAutoEtcPrefix is the autoetc prefix corresponding to checkExpectInstanceId.
-const wantAutoEtcPrefix = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+const (
+	// checkExpectUid is the uid value used by checkOpBehaviour to initialise [system.I].
+	checkExpectUid = 0xcafebabe
+	// wantAutoEtcPrefix is the autoetc prefix corresponding to checkExpectInstanceId.
+	wantAutoEtcPrefix = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+	// wantInstancePrefix is the SharePath corresponding to checkExpectInstanceId.
+	wantInstancePrefix = container.Nonexistent + "/tmp/hakurei.0/" + wantAutoEtcPrefix
+)
 
 // checkExpectInstanceId is the [state.ID] value used by checkOpBehaviour to initialise outcomeState.
 var checkExpectInstanceId = *(*state.ID)(bytes.Repeat([]byte{0xaa}, len(state.ID{})))
 
+type (
+	// pStateSysFunc is called before each test case is run to prepare outcomeStateSys.
+	pStateSysFunc = func(state *outcomeStateSys)
+	// pStateContainerFunc is called before each test case is run to prepare outcomeStateParams.
+	pStateContainerFunc = func(state *outcomeStateParams)
+
+	// extraCheckSysFunc is called to check outcomeStateSys and must not have side effects.
+	extraCheckSysFunc = func(t *testing.T, state *outcomeStateSys)
+	// extraCheckParamsFunc is called to check outcomeStateParams and must not have side effects.
+	extraCheckParamsFunc = func(t *testing.T, state *outcomeStateParams)
+)
+
+// insertsOps prepares outcomeStateParams to allow [container.Op] to be inserted.
+func insertsOps(next pStateContainerFunc) pStateContainerFunc {
+	return func(state *outcomeStateParams) {
+		state.params.Ops = new(container.Ops)
+
+		if next != nil {
+			next(state)
+		}
+	}
+}
+
+// afterSpRuntimeOp prepares outcomeStateParams for an outcomeOp meant to run after spRuntimeOp.
+func afterSpRuntimeOp(next pStateContainerFunc) pStateContainerFunc {
+	return func(state *outcomeStateParams) {
+		// emulates spRuntimeOp
+		state.runtimeDir = m("/run/user/1000")
+
+		if next != nil {
+			next(state)
+		}
+	}
+}
+
+// sysUsesInstance checks for use of the outcomeStateSys.instance method.
+func sysUsesInstance(next extraCheckSysFunc) extraCheckSysFunc {
+	return func(t *testing.T, state *outcomeStateSys) {
+		if want := m(wantInstancePrefix); !reflect.DeepEqual(state.sharePath, want) {
+			t.Errorf("outcomeStateSys: sharePath = %v, want %v", state.sharePath, want)
+		}
+
+		if next != nil {
+			next(t, state)
+		}
+	}
+}
+
+// paramsWantEnv checks outcomeStateParams.env for inserted entries on top of [hst.Config].
+func paramsWantEnv(config *hst.Config, wantEnv map[string]string, next extraCheckParamsFunc) extraCheckParamsFunc {
+	want := make(map[string]string, len(wantEnv)+len(config.Container.Env))
+	maps.Copy(want, wantEnv)
+	maps.Copy(want, config.Container.Env)
+	return func(t *testing.T, state *outcomeStateParams) {
+		if !maps.Equal(state.env, want) {
+			t.Errorf("toContainer: env = %#v, want %#v", state.env, want)
+		}
+
+		if next != nil {
+			next(t, state)
+		}
+	}
+}
+
 type opBehaviourTestCase struct {
 	name      string
 	newOp     func(isShim, clearUnexported bool) outcomeOp
 	newConfig func() *hst.Config
 
-	pStateSys     func(state *outcomeStateSys)
+	pStateSys     pStateSysFunc
 	toSystem      []stub.Call
 	wantSys       *system.I
-	extraCheckSys func(t *testing.T, state *outcomeStateSys)
+	extraCheckSys extraCheckSysFunc
 	wantErrSystem error
 
-	pStateContainer  func(state *outcomeStateParams)
+	pStateContainer  pStateContainerFunc
 	toContainer      []stub.Call
 	wantParams       *container.Params
-	extraCheckParams func(t *testing.T, state *outcomeStateParams)
+	extraCheckParams extraCheckParamsFunc
 	wantErrContainer error
 }
 
diff --git a/internal/app/spaccount_test.go b/internal/app/spaccount_test.go
index 7ebda46f..c5fb7b5b 100644
--- a/internal/app/spaccount_test.go
+++ b/internal/app/spaccount_test.go
@@ -1,7 +1,6 @@
 package app
 
 import (
-	"maps"
 	"os"
 	"syscall"
 	"testing"
@@ -42,48 +41,32 @@ func TestSpAccountOp(t *testing.T) {
 			return c
 		}, nil, []stub.Call{
 			// this op performs basic validation and does not make calls during toSystem
-		}, newI(), nil, nil, func(state *outcomeStateParams) {
-			state.params.Ops = new(container.Ops)
-		}, []stub.Call{
+		}, newI(), nil, nil, insertsOps(nil), []stub.Call{
 			// this op configures the container state and does not make calls during toContainer
 		}, &container.Params{
 			Dir: config.Container.Home,
 			Ops: new(container.Ops).
 				Place(m("/etc/passwd"), []byte("chronos:x:1000:100:Hakurei:/data/data/org.chromium.Chromium:/run/current-system/sw/bin/zsh\n")).
 				Place(m("/etc/group"), []byte("hakurei:x:100:\n")),
-		}, func(t *testing.T, state *outcomeStateParams) {
-			wantEnv := map[string]string{
-				"HOME":  config.Container.Home.String(),
-				"USER":  config.Container.Username,
-				"SHELL": config.Container.Shell.String(),
-			}
-			maps.Copy(wantEnv, config.Container.Env)
-			if !maps.Equal(state.env, wantEnv) {
-				t.Errorf("toContainer: env = %#v, want %#v", state.env, wantEnv)
-			}
-		}, nil},
+		}, paramsWantEnv(config, map[string]string{
+			"HOME":  config.Container.Home.String(),
+			"USER":  config.Container.Username,
+			"SHELL": config.Container.Shell.String(),
+		}, nil), nil},
 
 		{"success", func(bool, bool) outcomeOp { return spAccountOp{} }, hst.Template, nil, []stub.Call{
 			// this op performs basic validation and does not make calls during toSystem
-		}, newI(), nil, nil, func(state *outcomeStateParams) {
-			state.params.Ops = new(container.Ops)
-		}, []stub.Call{
+		}, newI(), nil, nil, insertsOps(nil), []stub.Call{
 			// this op configures the container state and does not make calls during toContainer
 		}, &container.Params{
 			Dir: config.Container.Home,
 			Ops: new(container.Ops).
 				Place(m("/etc/passwd"), []byte("chronos:x:1000:100:Hakurei:/data/data/org.chromium.Chromium:/run/current-system/sw/bin/zsh\n")).
 				Place(m("/etc/group"), []byte("hakurei:x:100:\n")),
-		}, func(t *testing.T, state *outcomeStateParams) {
-			wantEnv := map[string]string{
-				"HOME":  config.Container.Home.String(),
-				"USER":  config.Container.Username,
-				"SHELL": config.Container.Shell.String(),
-			}
-			maps.Copy(wantEnv, config.Container.Env)
-			if !maps.Equal(state.env, wantEnv) {
-				t.Errorf("toContainer: env = %#v, want %#v", state.env, wantEnv)
-			}
-		}, nil},
+		}, paramsWantEnv(config, map[string]string{
+			"HOME":  config.Container.Home.String(),
+			"USER":  config.Container.Username,
+			"SHELL": config.Container.Shell.String(),
+		}, nil), nil},
 	})
 }
diff --git a/internal/app/spcontainer_test.go b/internal/app/spcontainer_test.go
index 458588af..6b2354a2 100644
--- a/internal/app/spcontainer_test.go
+++ b/internal/app/spcontainer_test.go
@@ -2,7 +2,6 @@ package app
 
 import (
 	"errors"
-	"maps"
 	"os"
 	"reflect"
 	"syscall"
@@ -72,16 +71,9 @@ func TestSpParamsOp(t *testing.T) {
 				Proc(fhs.AbsProc).Tmpfs(hst.AbsPrivateTmp, 1<<12, 0755).
 				DevWritable(fhs.AbsDev, true).
 				Tmpfs(fhs.AbsDev.Append("shm"), 0, 01777),
+		}, paramsWantEnv(config, map[string]string{
+			"TERM": "xterm",
 		}, func(t *testing.T, state *outcomeStateParams) {
-			wantEnv := map[string]string{
-				"TERM": "xterm",
-			}
-			maps.Copy(wantEnv, config.Container.Env)
-			if !maps.Equal(state.env, wantEnv) {
-				t.Errorf("toContainer: env = %#v, want %#v", state.env, wantEnv)
-			}
-
-			const wantAutoEtcPrefix = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
 			if state.as.AutoEtcPrefix != wantAutoEtcPrefix {
 				t.Errorf("toContainer: as.AutoEtcPrefix = %q, want %q", state.as.AutoEtcPrefix, wantAutoEtcPrefix)
 			}
@@ -90,7 +82,7 @@ func TestSpParamsOp(t *testing.T) {
 			if !reflect.DeepEqual(state.filesystem, wantFilesystems) {
 				t.Errorf("toContainer: filesystem = %#v, want %#v", state.filesystem, wantFilesystems)
 			}
-		}, nil},
+		}), nil},
 
 		{"success", func(isShim, _ bool) outcomeOp {
 			if !isShim {
@@ -117,15 +109,9 @@ func TestSpParamsOp(t *testing.T) {
 				Proc(fhs.AbsProc).Tmpfs(hst.AbsPrivateTmp, 1<<12, 0755).
 				Bind(fhs.AbsDev, fhs.AbsDev, bits.BindWritable|bits.BindDevice).
 				Tmpfs(fhs.AbsDev.Append("shm"), 0, 01777),
+		}, paramsWantEnv(config, map[string]string{
+			"TERM": "xterm",
 		}, func(t *testing.T, state *outcomeStateParams) {
-			wantEnv := map[string]string{
-				"TERM": "xterm",
-			}
-			maps.Copy(wantEnv, config.Container.Env)
-			if !maps.Equal(state.env, wantEnv) {
-				t.Errorf("toContainer: env = %#v, want %#v", state.env, wantEnv)
-			}
-
 			if state.as.AutoEtcPrefix != wantAutoEtcPrefix {
 				t.Errorf("toContainer: as.AutoEtcPrefix = %q, want %q", state.as.AutoEtcPrefix, wantAutoEtcPrefix)
 			}
@@ -134,7 +120,7 @@ func TestSpParamsOp(t *testing.T) {
 			if !reflect.DeepEqual(state.filesystem, wantFilesystems) {
 				t.Errorf("toContainer: filesystem = %#v, want %#v", state.filesystem, wantFilesystems)
 			}
-		}, nil},
+		}), nil},
 	})
 }
 
@@ -159,6 +145,16 @@ func TestSpFilesystemOp(t *testing.T) {
 	}
 	configSmall := newConfigSmall()
 
+	needsApplyState := func(next pStateContainerFunc) pStateContainerFunc {
+		return func(state *outcomeStateParams) {
+			state.as = hst.ApplyState{AutoEtcPrefix: wantAutoEtcPrefix, Ops: opsAdapter{state.params.Ops}}
+
+			if next != nil {
+				next(state)
+			}
+		}
+	}
+
 	checkOpBehaviour(t, []opBehaviourTestCase{
 		{"readdir", func(bool, bool) outcomeOp {
 			return new(spFilesystemOp)
@@ -310,12 +306,9 @@ func TestSpFilesystemOp(t *testing.T) {
 			call("evalSymlinks", stub.ExpectArgs{"/var/lib/hakurei/base/org.nixos/.ro-store"}, nePrefix+"/var/lib/hakurei/base/org.nixos/.ro-store", nil),
 			call("evalSymlinks", stub.ExpectArgs{"/var/lib/hakurei/base/org.nixos/org.chromium.Chromium"}, nePrefix+"/var/lib/hakurei/base/org.nixos/org.chromium.Chromium", nil),
 			call("verbosef", stub.ExpectArgs{"hiding path %q from %q", []any{"/proc/nonexistent/eval/etc/dbus", "/etc/"}}, nil, nil),
-		}, newI(), nil, nil, func(state *outcomeStateParams) {
-			state.filesystem = configSmall.Container.Filesystem
-			state.params.Ops = new(container.Ops)
-			state.as = hst.ApplyState{AutoEtcPrefix: wantAutoEtcPrefix, Ops: opsAdapter{state.params.Ops}}
-			state.filesystem = append(state.filesystem, hst.FilesystemConfigJSON{})
-		}, []stub.Call{
+		}, newI(), nil, nil, insertsOps(needsApplyState(func(state *outcomeStateParams) {
+			state.filesystem = append(configSmall.Container.Filesystem, hst.FilesystemConfigJSON{})
+		})), []stub.Call{
 			// this op configures the container state and does not make calls during toContainer
 		}, nil, nil, &hst.AppError{
 			Step: "finalise",
@@ -341,11 +334,9 @@ func TestSpFilesystemOp(t *testing.T) {
 			call("evalSymlinks", stub.ExpectArgs{"/var/lib/hakurei/base/org.nixos/.ro-store"}, nePrefix+"/var/lib/hakurei/base/org.nixos/.ro-store", nil),
 			call("evalSymlinks", stub.ExpectArgs{"/var/lib/hakurei/base/org.nixos/org.chromium.Chromium"}, nePrefix+"/var/lib/hakurei/base/org.nixos/org.chromium.Chromium", nil),
 			call("verbosef", stub.ExpectArgs{"hiding path %q from %q", []any{"/proc/nonexistent/eval/etc/dbus", "/etc/"}}, nil, nil),
-		}, newI(), nil, nil, func(state *outcomeStateParams) {
+		}, newI(), nil, nil, insertsOps(needsApplyState(func(state *outcomeStateParams) {
 			state.filesystem = configSmall.Container.Filesystem
-			state.params.Ops = new(container.Ops)
-			state.as = hst.ApplyState{AutoEtcPrefix: wantAutoEtcPrefix, Ops: opsAdapter{state.params.Ops}}
-		}, []stub.Call{
+		})), []stub.Call{
 			// this op configures the container state and does not make calls during toContainer
 		}, &container.Params{
 			Ops: new(container.Ops).
@@ -386,11 +377,9 @@ func TestSpFilesystemOp(t *testing.T) {
 			call("evalSymlinks", stub.ExpectArgs{"/var/lib/hakurei/base/org.debian/sys"}, nePrefix+"/var/lib/hakurei/base/org.debian/sys", nil),
 			call("evalSymlinks", stub.ExpectArgs{"/var/lib/hakurei/base/org.debian/usr"}, nePrefix+"/var/lib/hakurei/base/org.debian/usr", nil),
 			call("evalSymlinks", stub.ExpectArgs{"/var/lib/hakurei/base/org.debian/var"}, nePrefix+"/var/lib/hakurei/base/org.debian/var", nil),
-		}, newI(), nil, nil, func(state *outcomeStateParams) {
+		}, newI(), nil, nil, insertsOps(needsApplyState(func(state *outcomeStateParams) {
 			state.filesystem = config.Container.Filesystem[1:]
-			state.params.Ops = new(container.Ops)
-			state.as = hst.ApplyState{AutoEtcPrefix: wantAutoEtcPrefix, Ops: opsAdapter{state.params.Ops}}
-		}, []stub.Call{
+		})), []stub.Call{
 			// this op configures the container state and does not make calls during toContainer
 		}, &container.Params{
 			Ops: new(container.Ops).
diff --git a/internal/app/spdbus.go b/internal/app/spdbus.go
index c2c1fefe..429674d0 100644
--- a/internal/app/spdbus.go
+++ b/internal/app/spdbus.go
@@ -12,6 +12,7 @@ import (
 func init() { gob.Register(new(spDBusOp)) }
 
 // spDBusOp maintains an xdg-dbus-proxy instance for the container.
+// Runs after spRuntimeOp.
 type spDBusOp struct {
 	// Whether to bind the system bus socket. Populated during toSystem.
 	ProxySystem bool
diff --git a/internal/app/spdbus_test.go b/internal/app/spdbus_test.go
index 0adf2be3..8dcf102c 100644
--- a/internal/app/spdbus_test.go
+++ b/internal/app/spdbus_test.go
@@ -1,8 +1,6 @@
 package app
 
 import (
-	"maps"
-	"reflect"
 	"syscall"
 	"testing"
 
@@ -18,7 +16,6 @@ import (
 
 func TestSpDBusOp(t *testing.T) {
 	config := hst.Template()
-	const instancePrefix = container.Nonexistent + "/tmp/hakurei.0/" + wantAutoEtcPrefix
 
 	checkOpBehaviour(t, []opBehaviourTestCase{
 		{"not enabled", func(bool, bool) outcomeOp {
@@ -41,11 +38,7 @@ func TestSpDBusOp(t *testing.T) {
 				"unix:path=/run/user/1000/bus",
 				"unix:path=/var/run/dbus/system_bus_socket",
 			}, nil),
-		}, nil, func(t *testing.T, state *outcomeStateSys) {
-			if want := m(instancePrefix); !reflect.DeepEqual(state.sharePath, want) {
-				t.Errorf("outcomeStateSys: sharePath = %v, want %v", state.sharePath, want)
-			}
-		}, &system.OpError{
+		}, nil, sysUsesInstance(nil), &system.OpError{
 			Op:     "dbus",
 			Err:    syscall.EINVAL,
 			Msg:    "message bus proxy configuration contains NUL byte",
@@ -66,7 +59,7 @@ func TestSpDBusOp(t *testing.T) {
 			call("isVerbose", stub.ExpectArgs{}, true, nil),
 			call("verbose", stub.ExpectArgs{[]any{"session bus proxy:", []string{
 				"unix:path=/run/user/1000/bus",
-				instancePrefix + "/bus",
+				wantInstancePrefix + "/bus",
 				"--filter",
 				"--talk=org.freedesktop.DBus",
 				"--talk=org.freedesktop.Notifications",
@@ -77,7 +70,7 @@ func TestSpDBusOp(t *testing.T) {
 			}}}, nil, nil),
 			call("verbose", stub.ExpectArgs{[]any{"message bus proxy final args:", helper.MustNewCheckedArgs(
 				"unix:path=/run/user/1000/bus",
-				instancePrefix+"/bus",
+				wantInstancePrefix+"/bus",
 				"--filter",
 				"--talk=org.freedesktop.DBus",
 				"--talk=org.freedesktop.Notifications",
@@ -88,40 +81,25 @@ func TestSpDBusOp(t *testing.T) {
 			)}}, nil, nil),
 		}, func() *system.I {
 			sys := system.New(panicMsgContext{}, message.NewMsg(nil), checkExpectUid)
-			sys.Ephemeral(system.Process, m(instancePrefix), 0711)
+			sys.Ephemeral(system.Process, m(wantInstancePrefix), 0711)
 			if err := sys.ProxyDBus(
 				dbus.NewConfig(config.ID, true, true), nil,
-				dbus.ProxyPair{"unix:path=/run/user/1000/bus", instancePrefix + "/bus"},
-				dbus.ProxyPair{"unix:path=/var/run/dbus/system_bus_socket", instancePrefix + "/system_bus_socket"},
+				dbus.ProxyPair{"unix:path=/run/user/1000/bus", wantInstancePrefix + "/bus"},
+				dbus.ProxyPair{"unix:path=/var/run/dbus/system_bus_socket", wantInstancePrefix + "/system_bus_socket"},
 			); err != nil {
 				t.Fatalf("cannot prepare sys: %v", err)
 			}
-			sys.UpdatePerm(m(instancePrefix+"/bus"), acl.Read, acl.Write)
+			sys.UpdatePerm(m(wantInstancePrefix+"/bus"), acl.Read, acl.Write)
 			return sys
-		}(), func(t *testing.T, state *outcomeStateSys) {
-			if want := m(instancePrefix); !reflect.DeepEqual(state.sharePath, want) {
-				t.Errorf("outcomeStateSys: sharePath = %v, want %v", state.sharePath, want)
-			}
-		}, nil, func(state *outcomeStateParams) {
-			state.params.Ops = new(container.Ops)
-
-			// emulates spRuntimeOp
-			state.runtimeDir = m("/run/user/1000")
-		}, []stub.Call{
+		}(), sysUsesInstance(nil), nil, insertsOps(afterSpRuntimeOp(nil)), []stub.Call{
 			// this op configures the container state and does not make calls during toContainer
 		}, &container.Params{
 			Ops: new(container.Ops).
-				Bind(m(instancePrefix+"/bus"),
+				Bind(m(wantInstancePrefix+"/bus"),
 					m("/run/user/1000/bus"), 0),
-		}, func(t *testing.T, state *outcomeStateParams) {
-			wantEnv := map[string]string{
-				"DBUS_SESSION_BUS_ADDRESS": "unix:path=/run/user/1000/bus",
-			}
-			maps.Copy(wantEnv, config.Container.Env)
-			if !maps.Equal(state.env, wantEnv) {
-				t.Errorf("toContainer: env = %#v, want %#v", state.env, wantEnv)
-			}
-		}, nil},
+		}, paramsWantEnv(config, map[string]string{
+			"DBUS_SESSION_BUS_ADDRESS": "unix:path=/run/user/1000/bus",
+		}, nil), nil},
 
 		{"success", func(isShim, _ bool) outcomeOp {
 			if !isShim {
@@ -136,7 +114,7 @@ func TestSpDBusOp(t *testing.T) {
 			call("isVerbose", stub.ExpectArgs{}, true, nil),
 			call("verbose", stub.ExpectArgs{[]any{"session bus proxy:", []string{
 				"unix:path=/run/user/1000/bus",
-				instancePrefix + "/bus",
+				wantInstancePrefix + "/bus",
 				"--filter",
 				"--talk=org.freedesktop.Notifications",
 				"--talk=org.freedesktop.FileManager1",
@@ -153,7 +131,7 @@ func TestSpDBusOp(t *testing.T) {
 			}}}, nil, nil),
 			call("verbose", stub.ExpectArgs{[]any{"system bus proxy:", []string{
 				"unix:path=/var/run/dbus/system_bus_socket",
-				instancePrefix + "/system_bus_socket",
+				wantInstancePrefix + "/system_bus_socket",
 				"--filter",
 				"--talk=org.bluez",
 				"--talk=org.freedesktop.Avahi",
@@ -161,7 +139,7 @@ func TestSpDBusOp(t *testing.T) {
 			}}}, nil, nil),
 			call("verbose", stub.ExpectArgs{[]any{"message bus proxy final args:", helper.MustNewCheckedArgs(
 				"unix:path=/run/user/1000/bus",
-				instancePrefix+"/bus",
+				wantInstancePrefix+"/bus",
 				"--filter",
 				"--talk=org.freedesktop.Notifications",
 				"--talk=org.freedesktop.FileManager1",
@@ -177,7 +155,7 @@ func TestSpDBusOp(t *testing.T) {
 				"--broadcast=org.freedesktop.portal.*=@/org/freedesktop/portal/*",
 
 				"unix:path=/var/run/dbus/system_bus_socket",
-				instancePrefix+"/system_bus_socket",
+				wantInstancePrefix+"/system_bus_socket",
 				"--filter",
 				"--talk=org.bluez",
 				"--talk=org.freedesktop.Avahi",
@@ -185,43 +163,28 @@ func TestSpDBusOp(t *testing.T) {
 			)}}, nil, nil),
 		}, func() *system.I {
 			sys := system.New(panicMsgContext{}, message.NewMsg(nil), checkExpectUid)
-			sys.Ephemeral(system.Process, m(instancePrefix), 0711)
+			sys.Ephemeral(system.Process, m(wantInstancePrefix), 0711)
 			if err := sys.ProxyDBus(
 				config.SessionBus, config.SystemBus,
-				dbus.ProxyPair{"unix:path=/run/user/1000/bus", instancePrefix + "/bus"},
-				dbus.ProxyPair{"unix:path=/var/run/dbus/system_bus_socket", instancePrefix + "/system_bus_socket"},
+				dbus.ProxyPair{"unix:path=/run/user/1000/bus", wantInstancePrefix + "/bus"},
+				dbus.ProxyPair{"unix:path=/var/run/dbus/system_bus_socket", wantInstancePrefix + "/system_bus_socket"},
 			); err != nil {
 				t.Fatalf("cannot prepare sys: %v", err)
 			}
-			sys.UpdatePerm(m(instancePrefix+"/bus"), acl.Read, acl.Write).
-				UpdatePerm(m(instancePrefix+"/system_bus_socket"), acl.Read, acl.Write)
+			sys.UpdatePerm(m(wantInstancePrefix+"/bus"), acl.Read, acl.Write).
+				UpdatePerm(m(wantInstancePrefix+"/system_bus_socket"), acl.Read, acl.Write)
 			return sys
-		}(), func(t *testing.T, state *outcomeStateSys) {
-			if want := m(instancePrefix); !reflect.DeepEqual(state.sharePath, want) {
-				t.Errorf("outcomeStateSys: sharePath = %v, want %v", state.sharePath, want)
-			}
-		}, nil, func(state *outcomeStateParams) {
-			state.params.Ops = new(container.Ops)
-
-			// emulates spRuntimeOp
-			state.runtimeDir = m("/run/user/1000")
-		}, []stub.Call{
+		}(), sysUsesInstance(nil), nil, insertsOps(afterSpRuntimeOp(nil)), []stub.Call{
 			// this op configures the container state and does not make calls during toContainer
 		}, &container.Params{
 			Ops: new(container.Ops).
-				Bind(m(instancePrefix+"/bus"),
+				Bind(m(wantInstancePrefix+"/bus"),
 					m("/run/user/1000/bus"), 0).
-				Bind(m(instancePrefix+"/system_bus_socket"),
+				Bind(m(wantInstancePrefix+"/system_bus_socket"),
 					m("/var/run/dbus/system_bus_socket"), 0),
-		}, func(t *testing.T, state *outcomeStateParams) {
-			wantEnv := map[string]string{
-				"DBUS_SESSION_BUS_ADDRESS": "unix:path=/run/user/1000/bus",
-				"DBUS_SYSTEM_BUS_ADDRESS":  "unix:path=/var/run/dbus/system_bus_socket",
-			}
-			maps.Copy(wantEnv, config.Container.Env)
-			if !maps.Equal(state.env, wantEnv) {
-				t.Errorf("toContainer: env = %#v, want %#v", state.env, wantEnv)
-			}
-		}, nil},
+		}, paramsWantEnv(config, map[string]string{
+			"DBUS_SESSION_BUS_ADDRESS": "unix:path=/run/user/1000/bus",
+			"DBUS_SYSTEM_BUS_ADDRESS":  "unix:path=/var/run/dbus/system_bus_socket",
+		}, nil), nil},
 	})
 }