public void TestInvalidFiles() { var tested = new CreateCommand(); Assert.IsFalse(tested.ExcelFileOk("gobledegook.xlsx", "test")); using (var temp = new TempFile("tmp.txt", string.Empty)) { Assert.IsFalse(tested.ExcelFileOk(temp._file.FullName, "test")); } using (var temp = new TempFile("tmp.xlsx", string.Empty)) { Assert.IsFalse(tested.ExcelFileOk(temp._file.FullName, "test")); } }