system: improve tests of the I struct

This cleans up for the test overhaul of this package.

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

system/acl.go

@@ -36,7 +36,7 @@ func (a *ACLUpdateOp) apply(sys *I) error {
 }
 
 func (a *ACLUpdateOp) revert(sys *I, ec *Criteria) error {
-	if ec.hasType(a) {
+	if ec.hasType(a.Type()) {
 		msg.Verbose("stripping ACL", a)
 		err := acl.Update(a.path, sys.uid)
 		if errors.Is(err, os.ErrNotExist) {

system/link.go

@@ -28,7 +28,7 @@ func (l *HardlinkOp) apply(*I) error {
 }
 
 func (l *HardlinkOp) revert(_ *I, ec *Criteria) error {
-	if ec.hasType(l) {
+	if ec.hasType(l.Type()) {
 		msg.Verbosef("removing hard link %q", l.dst)
 		return newOpError("hardlink", os.Remove(l.dst), true)
 	} else {

system/mkdir.go

@@ -50,7 +50,7 @@ func (m *MkdirOp) revert(_ *I, ec *Criteria) error {
 		return nil
 	}
 
-	if ec.hasType(m) {
+	if ec.hasType(m.Type()) {
 		msg.Verbose("destroying ephemeral directory", m)
 		return newOpError("mkdir", os.Remove(m.path), true)
 	} else {

system/output_test.go

@@ -209,18 +209,22 @@ func (ptc tcOp) test(t *testing.T, gotOps []Op, wantOps []Op, fn string) {
 		t.Run("criteria", func(t *testing.T) {
 			testCases := []struct {
 				name string
-				ec   *Criteria
+				ec   Enablement
 				want bool
 			}{
-				{"nil", nil, ptc.et != User},
-				{"self", newCriteria(ptc.et), true},
-				{"all", newCriteria(EWayland | EX11 | EDBus | EPulse | User | Process), true},
-				{"enablements", newCriteria(EWayland | EX11 | EDBus | EPulse), ptc.et != User && ptc.et != Process},
+				{"nil", 0xff, ptc.et != User},
+				{"self", ptc.et, true},
+				{"all", EWayland | EX11 | EDBus | EPulse | User | Process, true},
+				{"enablements", EWayland | EX11 | EDBus | EPulse, ptc.et != User && ptc.et != Process},
 			}
 
 			for _, tc := range testCases {
 				t.Run(tc.name, func(t *testing.T) {
-					if got := tc.ec.hasType(o); got != tc.want {
+					var criteria *Criteria
+					if tc.ec != 0xff {
+						criteria = (*Criteria)(&tc.ec)
+					}
+					if got := criteria.hasType(o.Type()); got != tc.want {
 						t.Errorf("hasType: got %v, want %v",
 							got, tc.want)
 					}
@@ -229,5 +233,3 @@ func (ptc tcOp) test(t *testing.T, gotOps []Op, wantOps []Op, fn string) {
 		})
 	}
 }
-
-func newCriteria(e Enablement) *Criteria { return (*Criteria)(&e) }

system/system.go

@@ -20,13 +20,13 @@ const (
 // Criteria specifies types of Op to revert.
 type Criteria Enablement
 
-func (ec *Criteria) hasType(o Op) bool {
+func (ec *Criteria) hasType(t Enablement) bool {
 	// nil criteria: revert everything except User
 	if ec == nil {
-		return o.Type() != User
+		return t != User
 	}
 
-	return Enablement(*ec)&o.Type() != 0
+	return Enablement(*ec)&t != 0
 }
 
 // Op is a reversible system operation.
@@ -92,7 +92,7 @@ func (sys *I) UID() int { return sys.uid }
 
 // Equal returns whether all [Op] instances held by sys matches that of target.
 func (sys *I) Equal(target *I) bool {
-	if target == nil || sys.uid != target.uid || len(sys.ops) != len(target.ops) {
+	if sys == nil || target == nil || sys.uid != target.uid || len(sys.ops) != len(target.ops) {
 		return false
 	}
 
@@ -149,7 +149,6 @@ func (sys *I) Revert(ec *Criteria) error {
 
 	// collect errors
 	errs := make([]error, len(sys.ops))
-
 	for i := range sys.ops {
 		errs[i] = sys.ops[len(sys.ops)-i-1].revert(sys, ec)
 	}

system/system_test.go

@@ -1,28 +1,37 @@
 package system_test
 
 import (
+	"reflect"
 	"strconv"
 	"testing"
+	_ "unsafe"
 
 	"hakurei.app/system"
 )
 
-func TestNew(t *testing.T) {
+//go:linkname criteriaHasType hakurei.app/system.(*Criteria).hasType
+func criteriaHasType(_ *system.Criteria, _ system.Enablement) bool
+
+func TestCriteria(t *testing.T) {
 	testCases := []struct {
-		uid int
+		name  string
+		ec, t system.Enablement
+		want  bool
 	}{
-		{150},
-		{149},
-		{148},
-		{147},
+		{"nil", 0xff, system.EWayland, true},
+		{"nil user", 0xff, system.User, false},
+		{"all", system.EWayland | system.EX11 | system.EDBus | system.EPulse | system.User | system.Process, system.Process, true},
 	}
 
 	for _, tc := range testCases {
-		t.Run("sys initialised with uid "+strconv.Itoa(tc.uid), func(t *testing.T) {
-			if got := system.New(t.Context(), tc.uid); got.UID() != tc.uid {
-				t.Errorf("New(%d) uid = %d, want %d",
-					tc.uid,
-					got.UID(), tc.uid)
+		t.Run(tc.name, func(t *testing.T) {
+			var criteria *system.Criteria
+			if tc.ec != 0xff {
+				criteria = (*system.Criteria)(&tc.ec)
+			}
+			if got := criteriaHasType(criteria, tc.t); got != tc.want {
+				t.Errorf("hasType: got %v, want %v",
+					got, tc.want)
 			}
 		})
 	}
@@ -45,86 +54,108 @@ func TestTypeString(t *testing.T) {
 	}
 
 	for _, tc := range testCases {
-		t.Run("label type string "+tc.want, func(t *testing.T) {
+		t.Run("label type string "+strconv.Itoa(int(tc.e)), func(t *testing.T) {
 			if got := system.TypeString(tc.e); got != tc.want {
-				t.Errorf("TypeString: %q, want %q",
-					got, tc.want)
+				t.Errorf("TypeString: %q, want %q", got, tc.want)
 			}
 		})
 	}
 }
 
-func TestI_Equal(t *testing.T) {
+func TestNew(t *testing.T) {
+	t.Run("panic", func(t *testing.T) {
+		t.Run("ctx", func(t *testing.T) {
+			defer func() {
+				want := "invalid call to New"
+				if r := recover(); r != want {
+					t.Errorf("recover: %v, want %v", r, want)
+				}
+			}()
+			system.New(nil, 0)
+		})
+
+		t.Run("uid", func(t *testing.T) {
+			defer func() {
+				want := "invalid call to New"
+				if r := recover(); r != want {
+					t.Errorf("recover: %v, want %v", r, want)
+				}
+			}()
+			system.New(t.Context(), -1)
+		})
+	})
+
+	sys := system.New(t.Context(), 0xdeadbeef)
+	if got := reflect.ValueOf(sys).Elem().FieldByName("ctx"); got.IsNil() {
+		t.Errorf("New: ctx = %#v", got)
+	}
+	if got := sys.UID(); got != 0xdeadbeef {
+		t.Errorf("UID: %d", got)
+	}
+}
+
+func TestEqual(t *testing.T) {
 	testCases := []struct {
 		name string
 		sys  *system.I
 		v    *system.I
 		want bool
 	}{
-		{
-			"simple UID",
+		{"simple UID",
 			system.New(t.Context(), 150),
 			system.New(t.Context(), 150),
-			true,
-		},
-		{
-			"simple UID differ",
+			true},
+
+		{"simple UID differ",
 			system.New(t.Context(), 150),
 			system.New(t.Context(), 151),
-			false,
-		},
-		{
-			"simple UID nil",
+			false},
+
+		{"simple UID nil",
 			system.New(t.Context(), 150),
 			nil,
-			false,
-		},
-		{
-			"op length mismatch",
+			false},
+
+		{"op length mismatch",
 			system.New(t.Context(), 150).
 				ChangeHosts("chronos"),
 			system.New(t.Context(), 150).
 				ChangeHosts("chronos").
 				Ensure("/run", 0755),
-			false,
-		},
-		{
-			"op value mismatch",
+			false},
+
+		{"op value mismatch",
 			system.New(t.Context(), 150).
 				ChangeHosts("chronos").
 				Ensure("/run", 0644),
 			system.New(t.Context(), 150).
 				ChangeHosts("chronos").
 				Ensure("/run", 0755),
-			false,
-		},
-		{
-			"op type mismatch",
+			false},
+
+		{"op type mismatch",
 			system.New(t.Context(), 150).
 				ChangeHosts("chronos").
 				CopyFile(new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 0, 256),
 			system.New(t.Context(), 150).
 				ChangeHosts("chronos").
 				Ensure("/run", 0755),
-			false,
-		},
-		{
-			"op equals",
+			false},
+
+		{"op equals",
 			system.New(t.Context(), 150).
 				ChangeHosts("chronos").
 				Ensure("/run", 0755),
 			system.New(t.Context(), 150).
 				ChangeHosts("chronos").
 				Ensure("/run", 0755),
-			true,
-		},
+			true},
 	}
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			if tc.sys.Equal(tc.v) != tc.want {
-				t.Errorf("Equal: got %v; want %v",
-					!tc.want, tc.want)
+				t.Errorf("Equal: %v, want %v", !tc.want, tc.want)
 			}
 		})
 	}

system/wayland.go

@@ -59,7 +59,7 @@ func (w *WaylandOp) apply(sys *I) error {
 }
 
 func (w *WaylandOp) revert(_ *I, ec *Criteria) error {
-	if ec.hasType(w) {
+	if ec.hasType(w.Type()) {
 		msg.Verbosef("removing wayland socket on %q", w.dst)
 		if err := os.Remove(w.dst); err != nil && !errors.Is(err, os.ErrNotExist) {
 			return newOpError("wayland", err, true)

system/xhost.go

@@ -22,7 +22,7 @@ func (x XHostOp) apply(*I) error {
 }
 
 func (x XHostOp) revert(_ *I, ec *Criteria) error {
-	if ec.hasType(x) {
+	if ec.hasType(x.Type()) {
 		msg.Verbosef("deleting entry %s from X11", x)
 		return newOpError("xhost",
 			xcb.ChangeHosts(xcb.HostModeDelete, xcb.FamilyServerInterpreted, "localuser\x00"+string(x)), false)