public void provide_value_throws_if_expression_is_null()
        {
            var converterExtension = new ExpressionConverterExtension();
            var ex = Assert.Throws <InvalidOperationException>(() => converterExtension.ProvideValue(null));

            Assert.Equal("No expression has been provided.", ex.Message);
        }
        public void provide_value_returns_appropriate_expression_converter()
        {
            var converterExtension = new ExpressionConverterExtension
            {
                Expression = "324 * 21 / {0}"
            };
            var expressionConverter = converterExtension.ProvideValue(null) as ExpressionConverter;

            Assert.NotNull(expressionConverter);
            Assert.Equal("324 * 21 / {0}", expressionConverter.Expression);
        }
        public void ctor_sets_expression_to_null()
        {
            var converterExtension = new ExpressionConverterExtension();

            Assert.Null(converterExtension.Expression);
        }
        public void ctor_that_takes_expression_sets_expression()
        {
            var converterExtension = new ExpressionConverterExtension("expr");

            Assert.Equal("expr", converterExtension.Expression);
        }