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// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package reflect_test
import (
. "reflect"
"strings"
"testing"
)
type structField struct {
name string
index []int
}
var fieldsTests = []struct {
testName string
val any
expect []structField
}{{
testName: "SimpleStruct",
val: struct {
A int
B string
C bool
}{},
expect: []structField{{
name: "A",
index: []int{0},
}, {
name: "B",
index: []int{1},
}, {
name: "C",
index: []int{2},
}},
}, {
testName: "NonEmbeddedStructMember",
val: struct {
A struct {
X int
}
}{},
expect: []structField{{
name: "A",
index: []int{0},
}},
}, {
testName: "EmbeddedExportedStruct",
val: struct {
SFG
}{},
expect: []structField{{
name: "SFG",
index: []int{0},
}, {
name: "F",
index: []int{0, 0},
}, {
name: "G",
index: []int{0, 1},
}},
}, {
testName: "EmbeddedUnexportedStruct",
val: struct {
sFG
}{},
expect: []structField{{
name: "sFG",
index: []int{0},
}, {
name: "F",
index: []int{0, 0},
}, {
name: "G",
index: []int{0, 1},
}},
}, {
testName: "TwoEmbeddedStructsWithCancelingMembers",
val: struct {
SFG
SF
}{},
expect: []structField{{
name: "SFG",
index: []int{0},
}, {
name: "G",
index: []int{0, 1},
}, {
name: "SF",
index: []int{1},
}},
}, {
testName: "EmbeddedStructsWithSameFieldsAtDifferentDepths",
val: struct {
SFGH3
SG1
SFG2
SF2
L int
}{},
expect: []structField{{
name: "SFGH3",
index: []int{0},
}, {
name: "SFGH2",
index: []int{0, 0},
}, {
name: "SFGH1",
index: []int{0, 0, 0},
}, {
name: "SFGH",
index: []int{0, 0, 0, 0},
}, {
name: "H",
index: []int{0, 0, 0, 0, 2},
}, {
name: "SG1",
index: []int{1},
}, {
name: "SG",
index: []int{1, 0},
}, {
name: "G",
index: []int{1, 0, 0},
}, {
name: "SFG2",
index: []int{2},
}, {
name: "SFG1",
index: []int{2, 0},
}, {
name: "SFG",
index: []int{2, 0, 0},
}, {
name: "SF2",
index: []int{3},
}, {
name: "SF1",
index: []int{3, 0},
}, {
name: "SF",
index: []int{3, 0, 0},
}, {
name: "L",
index: []int{4},
}},
}, {
testName: "EmbeddedPointerStruct",
val: struct {
*SF
}{},
expect: []structField{{
name: "SF",
index: []int{0},
}, {
name: "F",
index: []int{0, 0},
}},
}, {
testName: "EmbeddedNotAPointer",
val: struct {
M
}{},
expect: []structField{{
name: "M",
index: []int{0},
}},
}, {
testName: "RecursiveEmbedding",
val: Rec1{},
expect: []structField{{
name: "Rec2",
index: []int{0},
}, {
name: "F",
index: []int{0, 0},
}, {
name: "Rec1",
index: []int{0, 1},
}},
}, {
testName: "RecursiveEmbedding2",
val: Rec2{},
expect: []structField{{
name: "F",
index: []int{0},
}, {
name: "Rec1",
index: []int{1},
}, {
name: "Rec2",
index: []int{1, 0},
}},
}, {
testName: "RecursiveEmbedding3",
val: RS3{},
expect: []structField{{
name: "RS2",
index: []int{0},
}, {
name: "RS1",
index: []int{1},
}, {
name: "i",
index: []int{1, 0},
}},
}}
type SFG struct {
F int
G int
}
type SFG1 struct {
SFG
}
type SFG2 struct {
SFG1
}
type SFGH struct {
F int
G int
H int
}
type SFGH1 struct {
SFGH
}
type SFGH2 struct {
SFGH1
}
type SFGH3 struct {
SFGH2
}
type SF struct {
F int
}
type SF1 struct {
SF
}
type SF2 struct {
SF1
}
type SG struct {
G int
}
type SG1 struct {
SG
}
type sFG struct {
F int
G int
}
type RS1 struct {
i int
}
type RS2 struct {
RS1
}
type RS3 struct {
RS2
RS1
}
type M map[string]any
type Rec1 struct {
*Rec2
}
type Rec2 struct {
F string
*Rec1
}
func TestFields(t *testing.T) {
for _, test := range fieldsTests {
test := test
t.Run(test.testName, func(t *testing.T) {
typ := TypeOf(test.val)
fields := VisibleFields(typ)
if got, want := len(fields), len(test.expect); got != want {
t.Fatalf("unexpected field count; got %d want %d", got, want)
}
for j, field := range fields {
expect := test.expect[j]
t.Logf("field %d: %s", j, expect.name)
gotField := typ.FieldByIndex(field.Index)
// Unfortunately, FieldByIndex does not return
// a field with the same index that we passed in,
// so we set it to the expected value so that
// it can be compared later with the result of FieldByName.
gotField.Index = field.Index
expectField := typ.FieldByIndex(expect.index)
// ditto.
expectField.Index = expect.index
if !DeepEqual(gotField, expectField) {
t.Fatalf("unexpected field result\ngot %#v\nwant %#v", gotField, expectField)
}
// Sanity check that we can actually access the field by the
// expected name.
gotField1, ok := typ.FieldByName(expect.name)
if !ok {
t.Fatalf("field %q not accessible by name", expect.name)
}
if !DeepEqual(gotField1, expectField) {
t.Fatalf("unexpected FieldByName result; got %#v want %#v", gotField1, expectField)
}
}
})
}
}
// Must not panic with nil embedded pointer.
func TestFieldByIndexErr(t *testing.T) {
type A struct {
S string
}
type B struct {
*A
}
v := ValueOf(B{})
_, err := v.FieldByIndexErr([]int{0, 0})
if err == nil {
t.Fatal("expected error")
}
if !strings.Contains(err.Error(), "embedded struct field A") {
t.Fatal(err)
}
}