/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.sql.planner.assertions;
/**
* An implementation of ExpectedValueProvider<T> should hold the values and
* SymbolAliases needed to call T's constructor, and call
* SymbolAlias.toSymbol() to get actual Symbols to pass to T's constructor.
* Doing this ensures that changes to T's .equals() method that requires a
* change to T's constructor result in a compilation error.
*
* In particular, if adding a new field to T's .equals() method requires
* passing a value for that field to T's constuctor, using an
* ExpectedValueProvider that calls T's constructor will ensure that there is
* a compilation error to be fixed. By contrast, implementing the comparison logic
* in the test code and using SymbolAliases directly will likely cause tests to
* pass erroneously without any notification.
*/
public interface ExpectedValueProvider<T>
{
T getExpectedValue(SymbolAliases aliases);
}