Assert.NotNull - jnm2/nunit-docs-wiki GitHub Wiki
Assert.NotNull and Assert.IsNotNull test that the specified object is non-null. The two forms are provided for compatibility with past versions of NUnit and NUnitLite.
Assert.NotNull(object anObject);
Assert.NotNull(object anObject, string message, params object[] parms);
Assert.IsNotNull(object anObject);
Assert.IsNotNull(object anObject, string message, params object[] parms);