public static void IsNullCheck(string check) { var code = @" namespace N { using System; class C { bool M(string text) => text == null; } }".AssertReplace("text == null", check); var syntaxTree = CSharpSyntaxTree.ParseText(code); var expression = syntaxTree.Find <ExpressionSyntax>(check); Assert.AreEqual(true, NullCheck.IsNullCheck(expression, default, default, out var value));