pointers - 防止在测试时更改结构指针值

Question

我如何防止对结构值所做的任何更改仅保留在子测试中，即保持它们在子测试之外不受影响。我无法对结构进行任何更改，因为它们是使用swagger代码生成的自动生成的。这是一个例子:

package main

import (
    "testing"
)

func TestTyre(t *testing.T) {
    type Tyre struct {
        Color *string
    }
    type Vehicle struct {
        Tyre Tyre
    }

    color := "black"
    tyreForTest := Tyre{Color: &color}
    expectedTyreColor := color

    t.Run("negativeTest", func(t *testing.T) {
        tyre := tyreForTest               // would have worked if there weren't any pointer variables
        *tyre.Color = "blue"              // here I expect value to change only for this subtest

        vehicle := Vehicle{Tyre: tyre}
        actualTyreColor := vehicle.Tyre.Color

        ok := (expectedTyreColor == *actualTyreColor)
        if ok {
            t.Error("Color should be blue")
        }
    })
    t.Run("positiveTest", func(t *testing.T) {
        tyre := tyreForTest

        vehicle := Vehicle{Tyre: tyre}
        actualTyreColor := vehicle.Tyre.Color

        ok := (expectedTyreColor == *actualTyreColor)
        if !ok {
            t.Error("Color should be black, instead of", *actualTyreColor)
        }
    })
}

输出:

=== RUN   TestTyre
=== RUN   TestTyre/negativeTest
=== RUN   TestTyre/positiveTest
    TestTyre/positiveTest: prog.go:39: Color should be black, instead of blue
--- FAIL: TestTyre (0.00s)
    --- PASS: TestTyre/negativeTest (0.00s)
    --- FAIL: TestTyre/positiveTest (0.00s)
FAIL

Answer 1

您可以通过在测试用例之间不共享color变量来防止这种情况-每个测试用例都获得一个新的Tyre，但是它们都指向存储颜色值的相同内存。因此，当您在否定测试用例中更改tyre.Color时，您将更新变量color的值，而其他测试用例tyre.Color也指向该变量。

一个简单的解决方案是使用一个函数makeTyre()，该函数使用自己的内存获取全新的Tire，以存储颜色并为每个测试用例获取Tire:

package main

import (
        "testing"
)

type Tyre struct {
        Color *string
}
type Vehicle struct {
        Tyre Tyre
}

func makeTyre() Tyre {
        color := "black"
        return Tyre{Color: &color}
}

func TestTyre(t *testing.T) {
        expectedTyreColor := "black"

        t.Run("negativeTest", func(t *testing.T) {
                tyre := makeTyre()
                *tyre.Color = "blue"
                vehicle := Vehicle{Tyre: tyre}
                actualTyreColor := vehicle.Tyre.Color

                ok := (expectedTyreColor == *actualTyreColor)
                if ok {
                        t.Error("Color should be blue")
                }
        })
        t.Run("positiveTest", func(t *testing.T) {
                tyre := makeTyre()

                vehicle := Vehicle{Tyre: tyre}
                actualTyreColor := vehicle.Tyre.Color

                ok := (expectedTyreColor == *actualTyreColor)
                if !ok {
                        t.Error("Color should be black, instead of", *actualTyreColor)
                }
        })
}