goext/reflectext/casting_test.go

package reflectext

import (
	"reflect"
	"testing"
)

type aliasInt int
type aliasString string
type aliasFloat float64
type aliasBool bool

type aliasIntSlice []int
type aliasStringMap map[string]int
type aliasArr [3]int
type aliasIntPtr *int

type myStruct struct {
	A int
	B string
}

func TestUnderlying_Primitives(t *testing.T) {
	cases := []struct {
		in   reflect.Type
		want reflect.Kind
	}{
		{reflect.TypeFor[aliasInt](), reflect.Int},
		{reflect.TypeFor[aliasString](), reflect.String},
		{reflect.TypeFor[aliasFloat](), reflect.Float64},
		{reflect.TypeFor[aliasBool](), reflect.Bool},
	}
	for _, c := range cases {
		got := Underlying(c.in)
		if got.Kind() != c.want {
			t.Errorf("Underlying(%v).Kind() = %v, want %v", c.in, got.Kind(), c.want)
		}
		if got.Name() != "" && got != reflectBasicTypes[c.want] {
			t.Errorf("Underlying(%v) was not the basic type", c.in)
		}
	}
}

func TestUnderlying_UnnamedReturnsSelf(t *testing.T) {
	t1 := reflect.TypeFor[[]int]()
	got := Underlying(t1)
	if got != t1 {
		t.Errorf("Underlying of unnamed slice should be itself")
	}
}

func TestUnderlying_Slice(t *testing.T) {
	t1 := reflect.TypeFor[aliasIntSlice]()
	got := Underlying(t1)
	if got.Kind() != reflect.Slice {
		t.Errorf("expected slice kind, got %v", got.Kind())
	}
	if got.Elem().Kind() != reflect.Int {
		t.Errorf("expected element of int, got %v", got.Elem().Kind())
	}
	if got.Name() != "" {
		t.Errorf("underlying type should be unnamed, got name %q", got.Name())
	}
}

func TestUnderlying_Map(t *testing.T) {
	t1 := reflect.TypeFor[aliasStringMap]()
	got := Underlying(t1)
	if got.Kind() != reflect.Map {
		t.Errorf("expected map kind, got %v", got.Kind())
	}
}

func TestUnderlying_Array(t *testing.T) {
	t1 := reflect.TypeFor[aliasArr]()
	got := Underlying(t1)
	if got.Kind() != reflect.Array {
		t.Errorf("expected array kind, got %v", got.Kind())
	}
	if got.Len() != 3 {
		t.Errorf("expected array len 3, got %d", got.Len())
	}
}

func TestUnderlying_Pointer(t *testing.T) {
	t1 := reflect.TypeFor[aliasIntPtr]()
	got := Underlying(t1)
	if got.Kind() != reflect.Pointer {
		t.Errorf("expected pointer kind, got %v", got.Kind())
	}
	if got.Elem().Kind() != reflect.Int {
		t.Errorf("expected element kind int, got %v", got.Elem().Kind())
	}
}

func TestUnderlying_Func(t *testing.T) {
	type fnType func(a int, b string) (bool, error)
	t1 := reflect.TypeFor[fnType]()
	got := Underlying(t1)
	if got.Kind() != reflect.Func {
		t.Errorf("expected func kind, got %v", got.Kind())
	}
	if got.NumIn() != 2 || got.NumOut() != 2 {
		t.Errorf("unexpected in/out count: %d/%d", got.NumIn(), got.NumOut())
	}
}

func TestTryCast_AliasToBase(t *testing.T) {
	v := aliasInt(42)
	got, ok := TryCast[int](v)
	if !ok {
		t.Errorf("expected ok cast")
	}
	if got != 42 {
		t.Errorf("expected 42, got %v", got)
	}
}

func TestTryCast_SameType(t *testing.T) {
	got, ok := TryCast[int](42)
	if !ok {
		t.Errorf("expected ok cast")
	}
	if got != 42 {
		t.Errorf("expected 42, got %v", got)
	}
}

func TestTryCast_StringSameType(t *testing.T) {
	got, ok := TryCast[string]("hello")
	if !ok {
		t.Errorf("expected ok cast")
	}
	if got != "hello" {
		t.Errorf("expected hello, got %v", got)
	}
}

func TestTryCast_IncompatibleTypes(t *testing.T) {
	_, ok := TryCast[string](aliasInt(42))
	if ok {
		t.Errorf("expected fail cast int->string")
	}

	_, ok = TryCast[int](aliasString("foo"))
	if ok {
		t.Errorf("expected fail cast string->int")
	}
}

func TestTryCastType_AliasToBase(t *testing.T) {
	v := aliasInt(42)
	res, ok := TryCastType(v, reflect.TypeFor[int]())
	if !ok {
		t.Errorf("expected ok cast")
	}
	if i, isInt := res.(int); !isInt || i != 42 {
		t.Errorf("expected int(42), got %T:%v", res, res)
	}
}

func TestTryCastType_BaseToAlias(t *testing.T) {
	res, ok := TryCastType(42, reflect.TypeFor[aliasInt]())
	if !ok {
		t.Errorf("expected ok cast")
	}
	if i, isAlias := res.(aliasInt); !isAlias || i != aliasInt(42) {
		t.Errorf("expected aliasInt(42), got %T:%v", res, res)
	}
}

func TestTryCastType_Incompatible(t *testing.T) {
	_, ok := TryCastType("hello", reflect.TypeFor[int]())
	if ok {
		t.Errorf("expected fail cast string->int")
	}
}

func TestUnderlying_Struct(t *testing.T) {
	t1 := reflect.TypeFor[myStruct]()
	got := Underlying(t1)
	if got.Kind() != reflect.Struct {
		t.Errorf("expected struct kind, got %v", got.Kind())
	}
	if got.NumField() != 2 {
		t.Errorf("expected 2 fields, got %d", got.NumField())
	}
}