public void CanLookupPrecedence()
{
// Lookup precedence for unqualified names:
// defined value < standard function < field value
// Qualified names are always looked up on a row of fields
// defined with the qualifier. CONCAT is a standard function.
var env = new StandardEnvironment();
var row = new ConstantValueTestRow("row", "CONCAT", "FOO");
const string qualifier = "qualifier";
Assert.Catch <EvaluationException>(() => env.Lookup("FOO", null));
Assert.IsInstanceOf <Function>(env.Lookup("CONCAT", null));
Assert.Catch <EvaluationException>(() => env.Lookup("CONCAT", qualifier));
env.DefineFields(row, qualifier);
Assert.AreEqual("row", env.Lookup("FOO", null));
Assert.IsInstanceOf <Function>(env.Lookup("CONCAT", null));
Assert.AreEqual("row", env.Lookup("CONCAT", qualifier));
env.DefineValue("FOO", "foo");
env.DefineValue("CONCAT", "value");
Assert.AreEqual("foo", env.Lookup("FOO", null));
Assert.AreEqual("value", env.Lookup("CONCAT", null));
Assert.AreEqual("row", env.Lookup("CONCAT", qualifier));
env.ForgetValue("CONCAT");
env.ForgetValue("FOO");
Assert.AreEqual("row", env.Lookup("FOO", null));
Assert.IsInstanceOf <Function>(env.Lookup("CONCAT", null));
Assert.AreEqual("row", env.Lookup("CONCAT", qualifier));
env.ForgetFields("qualifier");
Assert.Catch <EvaluationException>(() => env.Lookup("FOO", null));
Assert.IsInstanceOf <Function>(env.Lookup("CONCAT", null));
Assert.Catch <EvaluationException>(() => env.Lookup("CONCAT", qualifier));
}