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reflect: add Value.IsZero

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Fixes #7501

Change-Id: Iac7c79cd4b30a90b14ed84bf1eba758972232a6c
Reviewed-on: https://go-review.googlesource.com/c/go/+/171337
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Romain Baugue 2019-04-10 16:20:43 +02:00 • committed by Ian Lance Taylor
parent 6d64dd731b
commit c40bffd905
2 changed files with 147 additions and 0 deletions
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107
src/reflect/all_test.go
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@ -1061,6 +1061,113 @@ func TestIsNil(t *testing.T) {
NotNil(fi, t)
}
func TestIsZero(t *testing.T) {
for i, tt := range []struct {
x interface{}
want bool
}{
// Booleans
{true, false},
{false, true},
// Numeric types
{int(0), true},
{int(1), false},
{int8(0), true},
{int8(1), false},
{int16(0), true},
{int16(1), false},
{int32(0), true},
{int32(1), false},
{int64(0), true},
{int64(1), false},
{uint(0), true},
{uint(1), false},
{uint8(0), true},
{uint8(1), false},
{uint16(0), true},
{uint16(1), false},
{uint32(0), true},
{uint32(1), false},
{uint64(0), true},
{uint64(1), false},
{float32(0), true},
{float32(1.2), false},
{float64(0), true},
{float64(1.2), false},
{math.Copysign(0, -1), false},
{complex64(0), true},
{complex64(1.2), false},
{complex128(0), true},
{complex128(1.2), false},
{complex(math.Copysign(0, -1), 0), false},
{complex(0, math.Copysign(0, -1)), false},
{complex(math.Copysign(0, -1), math.Copysign(0, -1)), false},
{uintptr(0), true},
{uintptr(128), false},
// Array
{Zero(TypeOf([5]string{})).Interface(), true},
{[5]string{"", "", "", "", ""}, true},
{[5]string{}, true},
{[5]string{"", "", "", "a", ""}, false},
// Chan
{(chan string)(nil), true},
{make(chan string), false},
{time.After(1), false},
// Func
{(func())(nil), true},
{New, false},
// Interface
{New(TypeOf(new(error)).Elem()).Elem(), true},
{(io.Reader)(strings.NewReader("")), false},
// Map
{(map[string]string)(nil), true},
{map[string]string{}, false},
{make(map[string]string), false},
// Ptr
{(*func())(nil), true},
{(*int)(nil), true},
{new(int), false},
// Slice
{[]string{}, false},
{([]string)(nil), true},
{make([]string, 0), false},
// Strings
{"", true},
{"not-zero", false},
// Structs
{T{}, true},
{T{123, 456.75, "hello", &_i}, false},
// UnsafePointer
{(unsafe.Pointer)(nil), true},
{(unsafe.Pointer)(new(int)), false},
} {
var x Value
if v, ok := tt.x.(Value); ok {
x = v
} else {
x = ValueOf(tt.x)
}
b := x.IsZero()
if b != tt.want {
t.Errorf("%d: IsZero((%s)(%+v)) = %t, want %t", i, x.Kind(), tt.x, b, tt.want)
}
if !Zero(TypeOf(tt.x)).IsZero() {
t.Errorf("%d: IsZero(Zero(TypeOf((%s)(%+v)))) is false", i, x.Kind(), tt.x)
}
}
func() {
defer func() {
if r := recover(); r == nil {
t.Error("should panic for invalid value")
}
}()
(Value{}).IsZero()
}()
}
func TestInterfaceExtraction(t *testing.T) {
var s struct {
W io.Writer