MsTestのprivateメンバ操作

テスト対象

/// <summary>
/// テスト対象クラス
/// </summary>
public class TestTargetClass
{
    /// <summary>
    /// Privateメンバ変数
    /// </summary>
    private int _privateMember = 0;

    /// <summary>
    /// PrivateStaticメンバ変数
    /// </summary>
    private static string _privateStaticMember = "";

    /// <summary>
    /// Publicメソッド
    /// </summary>
    /// <param name="param"></param>
    /// <returns></returns>
    public int PublicMethod(int param)
    {
        return param + 1;
    }

    /// <summary>
    /// Privateメソッド
    /// </summary>
    /// <param name="val1"></param>
    /// <param name="val2"></param>
    /// <returns></returns>
    private int PrivateMethod(int val1, int val2)
    {
        return _privateMember + val1 + val2;
    }

    /// <summary>
    /// Privateメソッド(非同期)
    /// </summary>
    /// <param name="val1"></param>
    /// <param name="val2"></param>
    /// <returns></returns>
    private async Task<int> PrivateMethodAsync(int val1, int val2)
    {
        await Task.Delay(0);
        return val1 + val2;
    }

    /// <summary>
    /// PrivateStaticメソッド
    /// </summary>
    /// <returns></returns>
    private static string GetPrivateStaticMember()
    {
        return _privateStaticMember;
    }
}

テストコード

Publicメソッド

通常ケース

[TestMethod()]
public void PublicMethodTest()
{
    var instance = new TestTargetClass();
    var ret = instance.PublicMethod(1);
    Assert.AreEqual(ret, 2);
}

Privateメソッド+Privateメンバ変数

PrivateObjectのSetFieldOrProperty()でメンバ変数を変更．
またはSetField()，SetProperty()．
privateObject.Invoke()でメソッド呼び出し．第2引数以降で呼び出したいメソッドの引数を設定．

[TestMethod()]
public void PrivateMethodTest()
{
    var instance = new TestTargetClass();
    var privateObject = new PrivateObject(instance);

    // メンバ変数値変更
    privateObject.SetFieldOrProperty("_privateMember", 100);
    // Privateメソッド呼び出し
    var ret = privateObject.Invoke("PrivateMethod", 100, 200);
    Assert.AreEqual(ret, 300);
}

Privateメソッド(非同期)

呼び出しを戻り値の型でくるんでawait．

[TestMethod()]
public async Task PrivateMethodAsyncTest()
{
    var instance = new TestTargetClass();
    var privateObject = new PrivateObject(instance);
    // 戻り値の型でくるんでawait
    var ret = await (privateObject.Invoke("PrivateMethodAsync", 100, 200) as Task<int>);
    Assert.AreEqual(ret, 300);
}

PrivateStaticメソッド+PrivateStaticメンバ変数

PrivateTypeのSetStaticFieldOrProperty()とInvokeStatic()を使用．
基本は通常のPrivateのときと同じ．

[TestMethod()]
public void GetPrivateStaticMemberTest()
{
    var privateType = new PrivateType(typeof(TestTargetClass));
    // static変数値変更
    privateType.SetStaticFieldOrProperty("_privateStaticMember", "ヨシッ！");
    // staticメソッド呼び出し
    var ret = privateType.InvokeStatic("GetPrivateStaticMember");

    Assert.AreEqual(ret, "ヨシッ！");
}