sizeof_test.go

Documentation: runtime

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package runtime_test
     6  
     7  import (
     8  	"reflect"
     9  	"runtime"
    10  	"testing"
    11  	"unsafe"
    12  )
    13  
    14  // Assert that the size of important structures do not change unexpectedly.
    15  
    16  func TestSizeof(t *testing.T) {
    17  	const _64bit = unsafe.Sizeof(uintptr(0)) == 8
    18  
    19  	var tests = []struct {
    20  		val    interface{} // type as a value
    21  		_32bit uintptr     // size on 32bit platforms
    22  		_64bit uintptr     // size on 64bit platforms
    23  	}{
    24  		{runtime.G{}, 236, 392},   // g, but exported for testing
    25  		{runtime.Sudog{}, 56, 88}, // sudog, but exported for testing
    26  	}
    27  
    28  	for _, tt := range tests {
    29  		want := tt._32bit
    30  		if _64bit {
    31  			want = tt._64bit
    32  		}
    33  		got := reflect.TypeOf(tt.val).Size()
    34  		if want != got {
    35  			t.Errorf("unsafe.Sizeof(%T) = %d, want %d", tt.val, got, want)
    36  		}
    37  	}
    38  }
    39
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