Use consistent pattern for mutating variables in tests.

- Use testutil.Set.

- Only export such variables to tests.

pkg/edit/highlight/highlight.go

@@ -22,9 +22,8 @@ type cmdRegion struct {
 	cmd string
 }
 
-// MaxBlockForLate specifies the maximum wait time to block for late results.
-// It can be changed for test cases.
-var MaxBlockForLate = 10 * time.Millisecond
+// Maximum wait time to block for late results. Can be changed for test cases.
+var maxBlockForLate = 10 * time.Millisecond
 
 // Highlights a piece of Elvish code.
 func highlight(code string, cfg Config, lateCb func(ui.Text)) (ui.Text, []error) {
@@ -117,7 +116,7 @@ func highlight(code string, cfg Config, lateCb func(ui.Text)) (ui.Text, []error)
 		select {
 		case late := <-lateCh:
 			return late, errors
-		case <-time.After(MaxBlockForLate):
+		case <-time.After(maxBlockForLate):
 			go func() {
 				lateCb(<-lateCh)
 			}()

pkg/edit/highlight/highlighter_test.go

@@ -24,7 +24,7 @@ var styles = ui.RuneStylesheet{
 
 func TestHighlighter_HighlightRegions(t *testing.T) {
 	// Force commands to be delivered synchronously.
-	MaxBlockForLate = testutil.Scaled(100 * time.Millisecond)
+	testutil.Set(t, &maxBlockForLate, testutil.Scaled(100*time.Millisecond))
 	hl := NewHighlighter(Config{
 		HasCommand: func(name string) bool { return name == "ls" },
 	})
@@ -127,7 +127,7 @@ func testThat(t *testing.T, hl *Highlighter, c c) {
 func TestHighlighter_HasCommand_LateResult_Async(t *testing.T) {
 	// When the HasCommand callback takes longer than maxBlockForLate, late
 	// results are delivered asynchronously.
-	MaxBlockForLate = testutil.Scaled(time.Millisecond)
+	testutil.Set(t, &maxBlockForLate, testutil.Scaled(time.Millisecond))
 	hl := NewHighlighter(Config{
 		// HasCommand is slow and only recognizes "ls".
 		HasCommand: func(cmd string) bool {
@@ -150,7 +150,7 @@ func TestHighlighter_HasCommand_LateResult_Async(t *testing.T) {
 func TestHighlighter_HasCommand_LateResult_Sync(t *testing.T) {
 	// When the HasCommand callback takes shorter than maxBlockForLate, late
 	// results are delivered asynchronously.
-	MaxBlockForLate = testutil.Scaled(100 * time.Millisecond)
+	testutil.Set(t, &maxBlockForLate, testutil.Scaled(100*time.Millisecond))
 	hl := NewHighlighter(Config{
 		// HasCommand is fast and only recognizes "ls".
 		HasCommand: func(cmd string) bool {
@@ -175,7 +175,7 @@ func TestHighlighter_HasCommand_LateResultOutOfOrder(t *testing.T) {
 	// "ls" and is dropped.
 
 	// Make sure that the HasCommand callback takes longer than maxBlockForLate.
-	MaxBlockForLate = testutil.Scaled(time.Millisecond)
+	testutil.Set(t, &maxBlockForLate, testutil.Scaled(time.Millisecond))
 
 	hlSecond := make(chan struct{})
 	hl := NewHighlighter(Config{

pkg/eval/builtin_fn_misc.go

@@ -409,15 +409,9 @@ func deprecate(fm *Frame, msg string) {
 	fm.Deprecate(msg, ctx, 0)
 }
 
-// TimeAfter is used by the sleep command to obtain a channel that is delivered
-// a value after the specified time.
-//
-// It is a variable to allow for unit tests to efficiently test the behavior of
-// the `sleep` command, both by eliminating an actual sleep and verifying the
-// duration was properly parsed.
-var TimeAfter = func(fm *Frame, d time.Duration) <-chan time.Time {
-	return time.After(d)
-}
+// Reference to time.After, can be mutated for testing. Takes an additional
+// Frame argument to allow inspection of the value of d in tests.
+var timeAfter = func(fm *Frame, d time.Duration) <-chan time.Time { return time.After(d) }
 
 //elvdoc:fn sleep
 //
@@ -486,7 +480,7 @@ func sleep(fm *Frame, duration any) error {
 	select {
 	case <-fm.Interrupts():
 		return ErrInterrupted
-	case <-TimeAfter(fm, d):
+	case <-timeAfter(fm, d):
 		return nil
 	}
 }

pkg/eval/builtin_fn_misc_test.go

@@ -108,13 +108,13 @@ func TestUseMod(t *testing.T) {
 	)
 }
 
-func timeAfterMock(fm *Frame, d time.Duration) <-chan time.Time {
-	fm.ValueOutput().Put(d) // report to the test framework the duration we received
-	return time.After(0)
-}
-
 func TestSleep(t *testing.T) {
-	TimeAfter = timeAfterMock
+	testutil.Set(t, TimeAfter,
+		func(fm *Frame, d time.Duration) <-chan time.Time {
+			fm.ValueOutput().Put(d)
+			return time.After(0)
+		})
+
 	Test(t,
 		That(`sleep 0`).Puts(0*time.Second),
 		That(`sleep 1`).Puts(1*time.Second),

pkg/eval/builtin_fn_misc_unix_test.go

@@ -7,32 +7,21 @@ import (
 	"testing"
 	"time"
 
+	"golang.org/x/sys/unix"
 	. "src.elv.sh/pkg/eval"
 	"src.elv.sh/pkg/testutil"
 
 	. "src.elv.sh/pkg/eval/evaltest"
 )
 
-func interruptedTimeAfterMock(fm *Frame, d time.Duration) <-chan time.Time {
-	if d == time.Second {
-		// Special-case intended to verity that a sleep can be interrupted.
-		go func() {
-			// Wait a little bit to ensure that the control flow in the "sleep"
-			// function is in the select block when the interrupt is sent.
-			time.Sleep(testutil.Scaled(time.Millisecond))
-			p, _ := os.FindProcess(os.Getpid())
-			p.Signal(os.Interrupt)
-		}()
-		return time.After(1 * time.Second)
-	}
-	panic("unreachable")
-}
+func TestSleep_Interrupt(t *testing.T) {
+	testutil.Set(t, TimeAfter,
+		func(fm *Frame, d time.Duration) <-chan time.Time {
+			go unix.Kill(os.Getpid(), unix.SIGINT)
+			return time.After(d)
+		})
 
-func TestInterruptedSleep(t *testing.T) {
-	TimeAfter = interruptedTimeAfterMock
 	Test(t,
-		// Special-case that should result in the sleep being interrupted. See
-		// timeAfterMock above.
 		That(`sleep 1s`).Throws(ErrInterrupted, "sleep 1s"),
 	)
 }

pkg/eval/pwd.go

@@ -18,13 +18,13 @@ type pwdVar struct {
 
 var _ vars.Var = pwdVar{}
 
-// Getwd allows for unit test error injection.
-var Getwd func() (string, error) = os.Getwd
+// Can be mutated in tests.
+var getwd func() (string, error) = os.Getwd
 
 // Get returns the current working directory. It returns "/unknown/pwd" when
 // it cannot be determined.
 func (pwdVar) Get() any {
-	pwd, err := Getwd()
+	pwd, err := getwd()
 	if err != nil {
 		// This should really use the path separator appropriate for the
 		// platform but in practice this hardcoded string works fine. Both

pkg/eval/pwd_test.go

@@ -52,15 +52,7 @@ func TestBuiltinPwd(t *testing.T) {
 
 // Verify the behavior when the CWD cannot be determined.
 func TestBuiltinPwd_GetwdError(t *testing.T) {
-	origGetwd := Getwd
-	Getwd = mockGetwdWithError
-	defer func() { Getwd = origGetwd }()
+	testutil.Set(t, Getwd, func() (string, error) { return "", errors.New("cwd unknown") })
 
-	Test(t,
-		That(`put $pwd`).Puts("/unknown/pwd"),
-	)
-}
-
-func mockGetwdWithError() (string, error) {
-	return "", errors.New("cwd unknown")
+	Test(t, That(`put $pwd`).Puts("/unknown/pwd"))
 }

pkg/eval/testexport_test.go

@@ -1,3 +1,8 @@
 package eval
 
-var GetHome = &getHome
+// Pointers to functions that can be mutated for testing.
+var (
+	GetHome   = &getHome
+	Getwd     = &getwd
+	TimeAfter = &timeAfter
+)

pkg/fsutil/gethome.go

@@ -9,9 +9,6 @@ import (
 	"src.elv.sh/pkg/env"
 )
 
-// CurrentUser allows for unit test error injection.
-var CurrentUser func() (*user.User, error) = user.Current
-
 // GetHome finds the home directory of a specified user. When given an empty
 // string, it finds the home directory of the current user.
 func GetHome(uname string) (string, error) {
@@ -28,7 +25,7 @@ func GetHome(uname string) (string, error) {
 	var u *user.User
 	var err error
 	if uname == "" {
-		u, err = CurrentUser()
+		u, err = user.Current()
 	} else {
 		u, err = user.Lookup(uname)
 	}