internal/outcome: rename from app

This is less ambiguous, and more accurately describes the purpose of the package.

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

1 files changed, 460 insertions, 0 deletions

diff --git a/internal/outcome/sppulse_test.go b/internal/outcome/sppulse_test.go
new file mode 100644
index 00000000..9aecb198
--- /dev/null
+++ b/internal/outcome/sppulse_test.go
@@ -0,0 +1,460 @@
+package outcome
+
+import (
+	"bytes"
+	"errors"
+	"os"
+	"syscall"
+	"testing"
+
+	"hakurei.app/container"
+	"hakurei.app/container/check"
+	"hakurei.app/container/stub"
+	"hakurei.app/hst"
+	"hakurei.app/system"
+	"hakurei.app/system/acl"
+)
+
+func TestSpPulseOp(t *testing.T) {
+	t.Parallel()
+
+	config := hst.Template()
+	sampleCookie := bytes.Repeat([]byte{0xfc}, pulseCookieSizeMax)
+
+	checkOpBehaviour(t, []opBehaviourTestCase{
+		{"not enabled", func(bool, bool) outcomeOp {
+			return new(spPulseOp)
+		}, func() *hst.Config {
+			c := hst.Template()
+			*c.Enablements = 0
+			return c
+		}, nil, nil, nil, nil, errNotEnabled, nil, nil, nil, nil, nil},
+
+		{"socketDir stat", func(isShim, _ bool) outcomeOp {
+			if !isShim {
+				return new(spPulseOp)
+			}
+			return &spPulseOp{Cookie: (*[256]byte)(sampleCookie)}
+		}, hst.Template, nil, []stub.Call{
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse"}, (*stubFi)(nil), stub.UniqueError(2)),
+		}, nil, nil, &hst.AppError{
+			Step: `access PulseAudio directory "/proc/nonexistent/xdg_runtime_dir/pulse"`,
+			Err:  stub.UniqueError(2),
+		}, nil, nil, nil, nil, nil},
+
+		{"socketDir nonexistent", func(bool, bool) outcomeOp {
+			return new(spPulseOp)
+		}, hst.Template, nil, []stub.Call{
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse"}, (*stubFi)(nil), os.ErrNotExist),
+		}, nil, nil, &hst.AppError{
+			Step: "finalise",
+			Err:  os.ErrNotExist,
+			Msg:  `PulseAudio directory "/proc/nonexistent/xdg_runtime_dir/pulse" not found`,
+		}, nil, nil, nil, nil, nil},
+
+		{"socket stat", func(bool, bool) outcomeOp {
+			return new(spPulseOp)
+		}, hst.Template, nil, []stub.Call{
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse"}, (*stubFi)(nil), nil),
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse/native"}, (*stubFi)(nil), stub.UniqueError(1)),
+		}, nil, nil, &hst.AppError{
+			Step: `access PulseAudio socket "/proc/nonexistent/xdg_runtime_dir/pulse/native"`,
+			Err:  stub.UniqueError(1),
+		}, nil, nil, nil, nil, nil},
+
+		{"socket nonexistent", func(bool, bool) outcomeOp {
+			return new(spPulseOp)
+		}, hst.Template, nil, []stub.Call{
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse"}, (*stubFi)(nil), nil),
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse/native"}, (*stubFi)(nil), os.ErrNotExist),
+		}, nil, nil, &hst.AppError{
+			Step: "finalise",
+			Err:  os.ErrNotExist,
+			Msg:  `PulseAudio directory "/proc/nonexistent/xdg_runtime_dir/pulse" found but socket does not exist`,
+		}, nil, nil, nil, nil, nil},
+
+		{"socket mode", func(bool, bool) outcomeOp {
+			return new(spPulseOp)
+		}, hst.Template, nil, []stub.Call{
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse"}, (*stubFi)(nil), nil),
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse/native"}, &stubFi{mode: 0660}, nil),
+		}, nil, nil, &hst.AppError{
+			Step: "finalise",
+			Err:  os.ErrInvalid,
+			Msg:  `unexpected permissions on "/proc/nonexistent/xdg_runtime_dir/pulse/native": -rw-rw----`,
+		}, nil, nil, nil, nil, nil},
+
+		{"cookie notAbs", func(bool, bool) outcomeOp {
+			return new(spPulseOp)
+		}, hst.Template, nil, []stub.Call{
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse"}, (*stubFi)(nil), nil),
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse/native"}, &stubFi{mode: 0666}, nil),
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, "proc/nonexistent/cookie", nil),
+		}, nil, nil, &hst.AppError{
+			Step: "locate PulseAudio cookie",
+			Err:  &check.AbsoluteError{Pathname: "proc/nonexistent/cookie"},
+		}, nil, nil, nil, nil, nil},
+
+		{"cookie loadFile", func(bool, bool) outcomeOp {
+			return new(spPulseOp)
+		}, hst.Template, nil, []stub.Call{
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse"}, (*stubFi)(nil), nil),
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse/native"}, &stubFi{mode: 0666}, nil),
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, "/proc/nonexistent/cookie", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/cookie"}, &stubFi{isDir: false, size: 1 << 8}, nil),
+			call("verbosef", stub.ExpectArgs{"loading %d bytes from %q", []any{1 << 8, "/proc/nonexistent/cookie"}}, nil, nil),
+			call("open", stub.ExpectArgs{"/proc/nonexistent/cookie"}, (*stubOsFile)(nil), stub.UniqueError(0)),
+		}, nil, nil, &hst.AppError{
+			Step: "open PulseAudio cookie",
+			Err:  stub.UniqueError(0),
+		}, nil, nil, nil, nil, nil},
+
+		{"cookie bad shim size", func(isShim, clearUnexported bool) outcomeOp {
+			if !isShim {
+				return new(spPulseOp)
+			}
+			op := &spPulseOp{Cookie: (*[pulseCookieSizeMax]byte)(sampleCookie), CookieSize: pulseCookieSizeMax}
+			if clearUnexported {
+				op.CookieSize += +0xfd
+			}
+			return op
+		}, hst.Template, nil, []stub.Call{
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse"}, (*stubFi)(nil), nil),
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse/native"}, &stubFi{mode: 0666}, nil),
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, "/proc/nonexistent/cookie", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/cookie"}, &stubFi{isDir: false, size: 1 << 8}, nil),
+			call("verbosef", stub.ExpectArgs{"loading %d bytes from %q", []any{1 << 8, "/proc/nonexistent/cookie"}}, nil, nil),
+			call("open", stub.ExpectArgs{"/proc/nonexistent/cookie"}, &stubOsFile{Reader: bytes.NewReader(sampleCookie)}, nil),
+		}, newI().
+			// state.ensureRuntimeDir
+			Ensure(m(wantRunDirPath), 0700).
+			UpdatePermType(system.User, m(wantRunDirPath), acl.Execute).
+			Ensure(m(wantRuntimePath), 0700).
+			UpdatePermType(system.User, m(wantRuntimePath), acl.Execute).
+			// state.runtime
+			Ephemeral(system.Process, m(wantRuntimeSharePath), 0700).
+			UpdatePerm(m(wantRuntimeSharePath), acl.Execute).
+			// toSystem
+			Link(m(wantRuntimePath+"/pulse/native"), m(wantRuntimeSharePath+"/pulse")), sysUsesRuntime(nil), nil, insertsOps(afterSpRuntimeOp(nil)), []stub.Call{
+			// this op configures the container state and does not make calls during toContainer
+		}, nil, nil, &hst.AppError{
+			Step: "finalise",
+			Err:  os.ErrInvalid,
+			Msg:  "unexpected PulseAudio cookie size",
+		}},
+
+		{"success cookie short", func(isShim, _ bool) outcomeOp {
+			if !isShim {
+				return new(spPulseOp)
+			}
+			sampleCookieTrunc := make([]byte, pulseCookieSizeMax)
+			copy(sampleCookieTrunc, sampleCookie[:len(sampleCookie)-0xe])
+			return &spPulseOp{Cookie: (*[pulseCookieSizeMax]byte)(sampleCookieTrunc), CookieSize: pulseCookieSizeMax - 0xe}
+		}, hst.Template, nil, []stub.Call{
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse"}, (*stubFi)(nil), nil),
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse/native"}, &stubFi{mode: 0666}, nil),
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, "/proc/nonexistent/cookie", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/cookie"}, &stubFi{isDir: false, size: pulseCookieSizeMax - 0xe}, nil),
+			call("verbosef", stub.ExpectArgs{"%s at %q is %d bytes shorter than expected", []any{"PulseAudio cookie", "/proc/nonexistent/cookie", int64(0xe)}}, nil, nil),
+			call("open", stub.ExpectArgs{"/proc/nonexistent/cookie"}, &stubOsFile{Reader: bytes.NewReader(sampleCookie[:len(sampleCookie)-0xe])}, nil),
+		}, newI().
+			// state.ensureRuntimeDir
+			Ensure(m(wantRunDirPath), 0700).
+			UpdatePermType(system.User, m(wantRunDirPath), acl.Execute).
+			Ensure(m(wantRuntimePath), 0700).
+			UpdatePermType(system.User, m(wantRuntimePath), acl.Execute).
+			// state.runtime
+			Ephemeral(system.Process, m(wantRuntimeSharePath), 0700).
+			UpdatePerm(m(wantRuntimeSharePath), acl.Execute).
+			// toSystem
+			Link(m(wantRuntimePath+"/pulse/native"), m(wantRuntimeSharePath+"/pulse")), sysUsesRuntime(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(wantRuntimeSharePath+"/pulse"), m("/run/user/1000/pulse/native"), 0).
+				Place(m("/.hakurei/pulse-cookie"), sampleCookie[:len(sampleCookie)-0xe]),
+		}, paramsWantEnv(config, map[string]string{
+			"PULSE_SERVER": "unix:/run/user/1000/pulse/native",
+			"PULSE_COOKIE": "/.hakurei/pulse-cookie",
+		}, nil), nil},
+
+		{"success cookie", func(isShim, _ bool) outcomeOp {
+			if !isShim {
+				return new(spPulseOp)
+			}
+			return &spPulseOp{Cookie: (*[pulseCookieSizeMax]byte)(sampleCookie), CookieSize: pulseCookieSizeMax}
+		}, hst.Template, nil, []stub.Call{
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse"}, (*stubFi)(nil), nil),
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse/native"}, &stubFi{mode: 0666}, nil),
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, "/proc/nonexistent/cookie", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/cookie"}, &stubFi{isDir: false, size: 1 << 8}, nil),
+			call("verbosef", stub.ExpectArgs{"loading %d bytes from %q", []any{1 << 8, "/proc/nonexistent/cookie"}}, nil, nil),
+			call("open", stub.ExpectArgs{"/proc/nonexistent/cookie"}, &stubOsFile{Reader: bytes.NewReader(sampleCookie)}, nil),
+		}, newI().
+			// state.ensureRuntimeDir
+			Ensure(m(wantRunDirPath), 0700).
+			UpdatePermType(system.User, m(wantRunDirPath), acl.Execute).
+			Ensure(m(wantRuntimePath), 0700).
+			UpdatePermType(system.User, m(wantRuntimePath), acl.Execute).
+			// state.runtime
+			Ephemeral(system.Process, m(wantRuntimeSharePath), 0700).
+			UpdatePerm(m(wantRuntimeSharePath), acl.Execute).
+			// toSystem
+			Link(m(wantRuntimePath+"/pulse/native"), m(wantRuntimeSharePath+"/pulse")), sysUsesRuntime(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(wantRuntimeSharePath+"/pulse"), m("/run/user/1000/pulse/native"), 0).
+				Place(m("/.hakurei/pulse-cookie"), sampleCookie),
+		}, paramsWantEnv(config, map[string]string{
+			"PULSE_SERVER": "unix:/run/user/1000/pulse/native",
+			"PULSE_COOKIE": "/.hakurei/pulse-cookie",
+		}, nil), nil},
+
+		{"success", func(bool, bool) outcomeOp {
+			return new(spPulseOp)
+		}, hst.Template, nil, []stub.Call{
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse"}, (*stubFi)(nil), nil),
+			call("stat", stub.ExpectArgs{wantRuntimePath + "/pulse/native"}, &stubFi{mode: 0666}, nil),
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"HOME"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"XDG_CONFIG_HOME"}, nil, nil),
+			call("verbose", stub.ExpectArgs{[]any{"cannot locate PulseAudio cookie (tried $PULSE_COOKIE, $XDG_CONFIG_HOME/pulse/cookie, $HOME/.pulse-cookie)"}}, nil, nil),
+		}, newI().
+			// state.ensureRuntimeDir
+			Ensure(m(wantRunDirPath), 0700).
+			UpdatePermType(system.User, m(wantRunDirPath), acl.Execute).
+			Ensure(m(wantRuntimePath), 0700).
+			UpdatePermType(system.User, m(wantRuntimePath), acl.Execute).
+			// state.runtime
+			Ephemeral(system.Process, m(wantRuntimeSharePath), 0700).
+			UpdatePerm(m(wantRuntimeSharePath), acl.Execute).
+			// toSystem
+			Link(m(wantRuntimePath+"/pulse/native"), m(wantRuntimeSharePath+"/pulse")), sysUsesRuntime(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(wantRuntimeSharePath+"/pulse"), m("/run/user/1000/pulse/native"), 0),
+		}, paramsWantEnv(config, map[string]string{
+			"PULSE_SERVER": "unix:/run/user/1000/pulse/native",
+		}, nil), nil},
+	})
+}
+
+func TestDiscoverPulseCookie(t *testing.T) {
+	t.Parallel()
+
+	fCheckPathname := func(k *kstub) error {
+		a, err := discoverPulseCookie(k)
+		k.Verbose(a)
+		return err
+	}
+
+	checkSimple(t, "discoverPulseCookie", []simpleTestCase{
+		{"override notAbs", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, "proc/nonexistent/pulse-cookie", nil),
+			call("verbose", stub.ExpectArgs{[]any{(*check.Absolute)(nil)}}, nil, nil),
+		}}, &hst.AppError{
+			Step: "locate PulseAudio cookie",
+			Err:  &check.AbsoluteError{Pathname: "proc/nonexistent/pulse-cookie"},
+		}},
+
+		{"success override", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, "/proc/nonexistent/pulse-cookie", nil),
+			call("verbose", stub.ExpectArgs{[]any{m("/proc/nonexistent/pulse-cookie")}}, nil, nil),
+		}}, nil},
+
+		{"home notAbs", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"HOME"}, "proc/nonexistent/home", nil),
+			call("verbose", stub.ExpectArgs{[]any{(*check.Absolute)(nil)}}, nil, nil),
+		}}, &hst.AppError{
+			Step: "locate PulseAudio cookie",
+			Err:  &check.AbsoluteError{Pathname: "proc/nonexistent/home"},
+		}},
+
+		{"home stat", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"HOME"}, "/proc/nonexistent/home", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/home/.pulse-cookie"}, (*stubFi)(nil), stub.UniqueError(1)),
+			call("verbose", stub.ExpectArgs{[]any{(*check.Absolute)(nil)}}, nil, nil),
+		}}, &hst.AppError{
+			Step: "access PulseAudio cookie",
+			Err:  stub.UniqueError(1),
+		}},
+
+		{"home nonexistent", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"HOME"}, "/proc/nonexistent/home", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/home/.pulse-cookie"}, (*stubFi)(nil), os.ErrNotExist),
+			call("lookupEnv", stub.ExpectArgs{"XDG_CONFIG_HOME"}, nil, nil),
+			call("verbose", stub.ExpectArgs{[]any{(*check.Absolute)(nil)}}, nil, nil),
+		}}, nil},
+
+		{"success home", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"HOME"}, "/proc/nonexistent/home", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/home/.pulse-cookie"}, &stubFi{}, nil),
+			call("verbose", stub.ExpectArgs{[]any{m("/proc/nonexistent/home/.pulse-cookie")}}, nil, nil),
+		}}, nil},
+
+		{"xdg notAbs", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"HOME"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"XDG_CONFIG_HOME"}, "proc/nonexistent/xdg", nil),
+			call("verbose", stub.ExpectArgs{[]any{(*check.Absolute)(nil)}}, nil, nil),
+		}}, &hst.AppError{
+			Step: "locate PulseAudio cookie",
+			Err:  &check.AbsoluteError{Pathname: "proc/nonexistent/xdg"},
+		}},
+
+		{"xdg stat", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"HOME"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"XDG_CONFIG_HOME"}, "/proc/nonexistent/xdg", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/xdg/pulse/cookie"}, (*stubFi)(nil), stub.UniqueError(0)),
+			call("verbose", stub.ExpectArgs{[]any{(*check.Absolute)(nil)}}, nil, nil),
+		}}, &hst.AppError{
+			Step: "access PulseAudio cookie",
+			Err:  stub.UniqueError(0),
+		}},
+
+		{"xdg dir", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"HOME"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"XDG_CONFIG_HOME"}, "/proc/nonexistent/xdg", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/xdg/pulse/cookie"}, &stubFi{isDir: true}, nil),
+			call("verbose", stub.ExpectArgs{[]any{(*check.Absolute)(nil)}}, nil, nil),
+		}}, nil},
+
+		{"success home dir xdg nonexistent", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"HOME"}, "/proc/nonexistent/home", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/home/.pulse-cookie"}, &stubFi{isDir: true}, nil),
+			call("lookupEnv", stub.ExpectArgs{"XDG_CONFIG_HOME"}, "/proc/nonexistent/xdg", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/xdg/pulse/cookie"}, (*stubFi)(nil), os.ErrNotExist),
+			call("verbose", stub.ExpectArgs{[]any{(*check.Absolute)(nil)}}, nil, nil),
+		}}, nil},
+
+		{"success home nonexistent xdg", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"HOME"}, "/proc/nonexistent/home", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/home/.pulse-cookie"}, (*stubFi)(nil), os.ErrNotExist),
+			call("lookupEnv", stub.ExpectArgs{"XDG_CONFIG_HOME"}, "/proc/nonexistent/xdg", nil),
+			call("stat", stub.ExpectArgs{"/proc/nonexistent/xdg/pulse/cookie"}, &stubFi{}, nil),
+			call("verbose", stub.ExpectArgs{[]any{m("/proc/nonexistent/xdg/pulse/cookie")}}, nil, nil),
+		}}, nil},
+
+		{"success empty environ", fCheckPathname, stub.Expect{Calls: []stub.Call{
+			call("lookupEnv", stub.ExpectArgs{"PULSE_COOKIE"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"HOME"}, nil, nil),
+			call("lookupEnv", stub.ExpectArgs{"XDG_CONFIG_HOME"}, nil, nil),
+			call("verbose", stub.ExpectArgs{[]any{(*check.Absolute)(nil)}}, nil, nil),
+		}}, nil},
+	})
+}
+
+func TestLoadFile(t *testing.T) {
+	t.Parallel()
+
+	fAfterWriteExact := func(k *kstub) error {
+		buf := make([]byte, 1<<8)
+		n, err := loadFile(k, k,
+			"simulated PulseAudio cookie",
+			"/home/ophestra/xdg/config/pulse/cookie",
+			buf)
+		k.Verbose(buf[:n])
+		return err
+	}
+
+	fAfterWrite := func(k *kstub) error {
+		buf := make([]byte, 1<<8+0xfd)
+		n, err := loadFile(k, k,
+			"simulated PulseAudio cookie",
+			"/home/ophestra/xdg/config/pulse/cookie",
+			buf)
+		k.Verbose(buf[:n])
+		return err
+	}
+
+	fBeforeWrite := func(k *kstub) error {
+		buf := make([]byte, 1<<8+0xfd)
+		n, err := loadFile(k, k,
+			"simulated PulseAudio cookie",
+			"/home/ophestra/xdg/config/pulse/cookie",
+			buf)
+		k.Verbose(n)
+
+		if !bytes.Equal(buf, make([]byte, len(buf))) {
+			t.Errorf("loadFile: buf = %#v", buf)
+		}
+		return err
+	}
+
+	sampleCookie := bytes.Repeat([]byte{0xfc}, pulseCookieSizeMax)
+	checkSimple(t, "loadFile", []simpleTestCase{
+		{"buf", func(k *kstub) error {
+			n, err := loadFile(k, k,
+				"simulated PulseAudio cookie",
+				"/home/ophestra/xdg/config/pulse/cookie",
+				nil)
+			k.Verbose(n)
+			return err
+		}, stub.Expect{Calls: []stub.Call{
+			call("verbose", stub.ExpectArgs{[]any{-1}}, nil, nil),
+		}}, errors.New("invalid buffer")},
+
+		{"stat", fBeforeWrite, stub.Expect{Calls: []stub.Call{
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, (*stubFi)(nil), stub.UniqueError(3)),
+			call("verbose", stub.ExpectArgs{[]any{-1}}, nil, nil),
+		}}, &hst.AppError{
+			Step: "access simulated PulseAudio cookie",
+			Err:  stub.UniqueError(3),
+		}},
+
+		{"dir", fBeforeWrite, stub.Expect{Calls: []stub.Call{
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &stubFi{isDir: true}, nil),
+			call("verbose", stub.ExpectArgs{[]any{-1}}, nil, nil),
+		}}, &hst.AppError{
+			Step: "read simulated PulseAudio cookie",
+			Err:  &os.PathError{Op: "stat", Path: "/home/ophestra/xdg/config/pulse/cookie", Err: syscall.EISDIR},
+		}},
+
+		{"oob", fBeforeWrite, stub.Expect{Calls: []stub.Call{
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &stubFi{size: 1<<8 + 0xff}, nil),
+			call("verbose", stub.ExpectArgs{[]any{-1}}, nil, nil),
+		}}, &hst.AppError{
+			Step: "finalise",
+			Err:  &os.PathError{Op: "stat", Path: "/home/ophestra/xdg/config/pulse/cookie", Err: syscall.ENOMEM},
+			Msg:  `simulated PulseAudio cookie at "/home/ophestra/xdg/config/pulse/cookie" exceeds expected size`,
+		}},
+
+		{"open", fBeforeWrite, stub.Expect{Calls: []stub.Call{
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &stubFi{size: 1 << 8}, nil),
+			call("verbosef", stub.ExpectArgs{"%s at %q is %d bytes shorter than expected", []any{"simulated PulseAudio cookie", "/home/ophestra/xdg/config/pulse/cookie", int64(0xfd)}}, nil, nil),
+			call("open", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, (*stubOsFile)(nil), stub.UniqueError(2)),
+			call("verbose", stub.ExpectArgs{[]any{-1}}, nil, nil),
+		}}, &hst.AppError{Step: "open simulated PulseAudio cookie", Err: stub.UniqueError(2)}},
+
+		{"read", fBeforeWrite, stub.Expect{Calls: []stub.Call{
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &stubFi{size: 1 << 8}, nil),
+			call("verbosef", stub.ExpectArgs{"%s at %q is %d bytes shorter than expected", []any{"simulated PulseAudio cookie", "/home/ophestra/xdg/config/pulse/cookie", int64(0xfd)}}, nil, nil),
+			call("open", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &stubOsFile{Reader: errorReader{stub.UniqueError(1)}}, nil),
+			call("verbose", stub.ExpectArgs{[]any{-1}}, nil, nil),
+		}}, &hst.AppError{Step: "read simulated PulseAudio cookie", Err: stub.UniqueError(1)}},
+
+		{"short close", fAfterWrite, stub.Expect{Calls: []stub.Call{
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &stubFi{size: 1 << 8}, nil),
+			call("verbosef", stub.ExpectArgs{"%s at %q is %d bytes shorter than expected", []any{"simulated PulseAudio cookie", "/home/ophestra/xdg/config/pulse/cookie", int64(0xfd)}}, nil, nil),
+			call("open", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &stubOsFile{closeErr: stub.UniqueError(0), Reader: bytes.NewReader(sampleCookie)}, nil),
+			call("verbose", stub.ExpectArgs{[]any{sampleCookie}}, nil, nil),
+		}}, &hst.AppError{Step: "close simulated PulseAudio cookie", Err: stub.UniqueError(0)}},
+
+		{"success", fAfterWriteExact, stub.Expect{Calls: []stub.Call{
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &stubFi{size: 1 << 8}, nil),
+			call("verbosef", stub.ExpectArgs{"loading %d bytes from %q", []any{1 << 8, "/home/ophestra/xdg/config/pulse/cookie"}}, nil, nil),
+			call("open", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &stubOsFile{Reader: bytes.NewReader(sampleCookie)}, nil),
+			call("verbose", stub.ExpectArgs{[]any{sampleCookie}}, nil, nil),
+		}}, nil},
+	})
+}