Fix Cast to interfaces

totemcaf · Aug 19, 2022 · 0351561 · 0351561
1 parent ca2637d
commit 0351561
Show file tree

Hide file tree

Showing 2 changed files with 22 additions and 6 deletions.
diff --git a/nils/nils.go b/nils/nils.go
@@ -36,12 +36,13 @@ func Copy[T any](value *T) *T {
 	return &t
 }
 
-func CastOrNil[T any](value any) *T {
+func CastOrNil[T any](value any) T {
 	if value == nil {
-		return nil
+		var t T
+		return t
 	}
 
-	t, ok := value.(*T)
+	t, ok := value.(T)
 
 	if !ok {
 		panic("cannot cast value to type " + reflect.TypeOf(value).String())

diff --git a/nils/nils_test.go b/nils/nils_test.go
@@ -54,16 +54,31 @@ func Test_Copy_returns_copied_value_for_not_nil(t *testing.T) {
 func Test_CastOrNil_returns_nil_for_nil(t *testing.T) {
 	var aNil *string = nil
 
-	assert.Equal(t, aNil, CastOrNil[string](aNil))
+	assert.Equal(t, aNil, CastOrNil[*string](aNil))
+}
+
+type ISample interface {
+	GetValue() string
 }
 
 type sample struct {
 	aValue string
 }
 
+func (s *sample) GetValue() string {
+	return s.aValue
+}
+
 func Test_CastOrNil_returns_casted_value_for_not_nil(t *testing.T) {
 	var aValue sample = sample{aString}
 
-	assert.Equal(t, &aValue, CastOrNil[sample](&aValue))
-	assert.IsType(t, &sample{}, CastOrNil[sample](&aValue))
+	assert.Equal(t, &aValue, CastOrNil[*sample](&aValue))
+	assert.IsType(t, &sample{}, CastOrNil[*sample](&aValue))
+}
+
+func Test_CastOrNil_returns_casted_value_for_interfaces(t *testing.T) {
+	var aValue sample = sample{aString}
+
+	assert.Equal(t, &aValue, CastOrNil[ISample](&aValue))
+	assert.IsType(t, &sample{}, CastOrNil[ISample](&aValue))
 }