ClassicAssert.True
ClassicAssert.True and ClassicAssert.IsTrue test that the specified condition is true. The two forms are provided for compatibility with past versions of NUnit and NUnitLite.
ClassicAssert.True(bool condition);
ClassicAssert.True(bool condition, string message, params object[] params);
ClassicAssert.IsTrue(bool condition);
ClassicAssert.IsTrue(bool condition, string message, params object[] params);
You can also use Assert.That with a Boolean argument to achieve the same result.
[Test]
public void True_Examples()
{
ClassicAssert.True(2 + 2 == 4);
ClassicAssert.IsTrue(true);
ClassicAssert.True("Hello".StartsWith("H"));
}