improve DefaultArg

Author: wxiaoguang

modules/testlogger/testlogger.go

@@ -93,7 +93,7 @@ func (w *testLoggerWriterCloser) Reset() {
 func PrintCurrentTest(t testing.TB, skip ...int) func() {
 	t.Helper()
 	start := time.Now()
-	actualSkip := util.DefArgZero(skip) + 1
+	actualSkip := util.DefaultArg(skip) + 1
 	_, filename, line, _ := runtime.Caller(actualSkip)
 
 	if log.CanColorStdout {

modules/util/util.go

@@ -230,18 +230,23 @@ func IfZero[T comparable](v, def T) T {
 	return v
 }
 
-// DefArg helps the "optional argument" in Golang: func(foo string, optionalArg ...int)
-// it returns the first non-zero value from the given optional argument,
-// or the default value if there is no optional argument.
-func DefArg[T any](defArgs []T, def T) (ret T) {
-	if len(defArgs) == 1 {
-		return defArgs[0]
+// DefaultArg helps the "optional argument" in Golang:
+//
+//	func foo(optionalArg ...int) { return DefaultArg(optionalArg) }
+//		calling `foo()` gets 0, calling `foo(100)` gets 100
+//	func bar(optionalArg ...int) { return DefaultArg(optionalArg, 42) }
+//		calling `bar()` gets 42, calling `bar(100)` gets 100
+//
+// Passing more than 1 item to `optionalArg` or `def` is undefined behavior.
+// At the moment it only returns the first argument.
+func DefaultArg[T any](optionalArg []T, def ...T) (ret T) {
+	if len(optionalArg) >= 1 {
+		return optionalArg[0]
 	}
-	return def
-}
-
-func DefArgZero[T any](defArgs []T) (ret T) {
-	return DefArg(defArgs, ret)
+	if len(def) >= 1 {
+		return def[0]
+	}
+	return ret
 }
 
 func ReserveLineBreakForTextarea(input string) string {

modules/util/util_test.go

@@ -240,3 +240,16 @@ func TestReserveLineBreakForTextarea(t *testing.T) {
 	assert.Equal(t, ReserveLineBreakForTextarea("test\r\ndata"), "test\ndata")
 	assert.Equal(t, ReserveLineBreakForTextarea("test\r\ndata\r\n"), "test\ndata\n")
 }
+
+func TestDefaultArg(t *testing.T) {
+	foo := func(other any, optionalArg ...int) int {
+		return DefaultArg(optionalArg)
+	}
+	bar := func(other any, optionalArg ...int) int {
+		return DefaultArg(optionalArg, 42)
+	}
+	assert.Equal(t, 0, foo(nil))
+	assert.Equal(t, 100, foo(nil, 100))
+	assert.Equal(t, 42, bar(nil))
+	assert.Equal(t, 100, bar(nil, 100))
+}

tests/test_utils.go

@@ -262,7 +262,7 @@ func PrepareCleanPackageData(t testing.TB) {
 
 func PrepareTestEnv(t testing.TB, skip ...int) func() {
 	t.Helper()
-	deferFn := PrintCurrentTest(t, util.DefArgZero(skip)+1)
+	deferFn := PrintCurrentTest(t, util.DefaultArg(skip)+1)
 
 	// load database fixtures
 	assert.NoError(t, unittest.LoadFixtures())
@@ -276,7 +276,7 @@ func PrepareTestEnv(t testing.TB, skip ...int) func() {
 
 func PrintCurrentTest(t testing.TB, skip ...int) func() {
 	t.Helper()
-	return testlogger.PrintCurrentTest(t, util.DefArgZero(skip)+1)
+	return testlogger.PrintCurrentTest(t, util.DefaultArg(skip)+1)
 }
 
 // Printf takes a format and args and prints the string to os.Stdout