public void GetCommonBaseTypeSame() {
SymbolTypeMap<TestToken> symbolTypeMap = new SymbolTypeMap<TestToken>();
Assert.Equal(typeof(TestValue), symbolTypeMap.GetCommonBaseType(typeof(TestValue), typeof(TestValue)));
}
public void GetCommonBaseTypeAncestor() {
SymbolTypeMap<TestToken> symbolTypeMap = new SymbolTypeMap<TestToken>();
Assert.Equal(typeof(TestOperation), symbolTypeMap.GetCommonBaseType(typeof(TestAdd), typeof(TestSubtract)));
}