public void UnescapeLiterals(string source, string expected)
        {
            var patternParserMock = new Mock<IPatternParser>();
            var libraryMock = new Mock<IFormatterLibrary>();
            var subject = new MessageFormatter(patternParserMock.Object, libraryMock.Object, false, locale: "en");

            var actual = subject.UnescapeLiterals(new StringBuilder(source)).ToString();
            Assert.Equal(expected, actual);
        }