check: Add Zero*

check/check.cmd.go

@@ -120,6 +120,18 @@ var funcs = []Func{
 		Check: "checkNotNil(v)",
 		Doc:   "Check that v is not nil. This is a strict equality check.",
 	},
+	{
+		Name:  "Zero",
+		Args:  "v any",
+		Check: "checkZero(v)",
+		Doc:   "Check that v is the zero value for its type.",
+	},
+	{
+		Name:  "NotZero",
+		Args:  "v any",
+		Check: "checkNotZero(v)",
+		Doc:   "Check that v is not the zero value for its type.",
+	},
 	{
 		Name:  "ErrIs",
 		Args:  "err, target error",

check/check.go

@@ -133,6 +133,24 @@ func checkNotNil(v any) (string, bool) {
 	return "Expected something, got nil", false
 }
 
+func checkZero(v any) (string, bool) {
+	rv := reflect.ValueOf(v)
+	if !rv.IsValid() || rv.IsZero() {
+		return "", true
+	}
+
+	return equalMsg(v, reflect.Zero(rv.Type()).Interface()), false
+}
+
+func checkNotZero(v any) (string, bool) {
+	rv := reflect.ValueOf(v)
+	if rv.IsValid() && !rv.IsZero() {
+		return "", true
+	}
+
+	return "Expected something, got {}", false
+}
+
 func checkErrIs(err, target error) (string, bool) {
 	if errors.Is(err, target) {
 		return "", true

check/check_test.go

@@ -60,6 +60,22 @@ func TestCheckNotNil(t *testing.T) {
 	testCheck(checkNotNil(nil))(t, false)
 }
 
+func TestCheckZero(t *testing.T) {
+	testCheck(checkZero(nil))(t, true)
+	testCheck(checkZero(0))(t, true)
+	testCheck(checkZero((*int)(nil)))(t, true)
+	testCheck(checkZero(1))(t, false)
+	testCheck(checkZero(new(int)))(t, false)
+}
+
+func TestCheckNotZero(t *testing.T) {
+	testCheck(checkNotZero(1))(t, true)
+	testCheck(checkNotZero(new(int)))(t, true)
+	testCheck(checkNotZero(nil))(t, false)
+	testCheck(checkNotZero(0))(t, false)
+	testCheck(checkNotZero((*int)(nil)))(t, false)
+}
+
 func TestCheckErrIs(t *testing.T) {
 	err := &os.PathError{
 		Op:   "test",