public void FileCountByExtension() { // Arrange var subject = new Linq(); var expectedList = new Dictionary <string, int> { { "frx", 1 }, { "txt", 3 }, { "dbf", 1 }, { "pdf", 2 }, { "frt", 1 }, { "xml", 1 } }; // Act var actual = subject.GetFileCountByExtension( new List <string> { "aaa.frx", "bbb.TXT", "xyz.dbf", "abc.pdf", "aaaa.PDF", "xyz.frt", "abc.xml", "ccc.txt", "zzz.txt" }); // Assert Assert.AreEqual(6, actual.Count); foreach (var actualFc in actual) { Assert.IsTrue(expectedList.Contains(actualFc)); } }