public void ShouldSortNumberStringArray() { var sorter = CreateSorter <FileLine>(new FileLineSizeCalculator()); var sourceArray = new FileLine[] { FileLine.Parse("415. Apple"), FileLine.Parse("30432. Something something something"), FileLine.Parse("1. Apple"), FileLine.Parse("32. Cherry is the best"), FileLine.Parse("2. Banana is yellow") }; var expectedArray = new FileLine[] { FileLine.Parse("1. Apple"), FileLine.Parse("415. Apple"), FileLine.Parse("2. Banana is yellow"), FileLine.Parse("32. Cherry is the best"), FileLine.Parse("30432. Something something something") }; var sortedArray = sorter.Sort(sourceArray); CollectionAssert.AreEqual(expectedArray, sortedArray); }