When making a test class with FsUnit, [] is not a valid attribute on a member. Why?

Question

I'm fiddling with a new F# project (of which I haven't made many), and I'm aiming to do it in a TDD fashion. So, I'm trying to familiarize myself with using FsUnit, since I have a lot of experience using NUnit in C# projects, and it seems a pretty common framework to use.

My code looks like the following:

module DatabaseReaderTest

open NUnit.Framework
open FsUnit

[<TestFixture>]
type DatabaseReaderTest ()=

    [<Test>]
    member x.ResultsAreReturnedFromDatabase =
        DatabaseReader.result.GetSqlString(1) |> should equal "first"

As far as I can tell, this follows the example on the FsUnit home page (http://fsunit.codeplex.com/), but the compiler tells me that [<Test>] is not a valid attribute on this language element, by which I assume it means member.

Any tips on what I'm doing wrong here?

Thanks!

You might also be interested in checking out Unquote, http://code.google.com/p/unquote/. Then you'd write your test assertion as `test <@ DatabaseReader.result.GetSqlString(1) = "first" @>` and enjoy plain F# boolean assertion syntax with full compiler static type checking and nice step-by-step failure messages which reduce the need to attach the debugger to analyze failure cause. — Stephen Swensen, Oct 08 '11 at 16:51

score 7 · Accepted Answer · answered Oct 08 '11 at 15:33

7

You probably need to use a method rather than a property. Just add a () argument of type unit.

answered Oct 08 '11 at 15:33

kvb

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It's always the little things. Thanks. – McMuttons Oct 08 '11 at 15:35

score 4 · Answer 2 · answered Oct 08 '11 at 15:48

4

As a side-note, if you don't need any custom initialization before tests are run and if you're using a recent version of NUnit, then you should be able to use module with let bound functions for your tests.

This gives you a bit more lightweight syntax. Some people also like to use double-tick syntax that makes it possible to write the test name as an ordinary English sentence (which shows nicely in test runner):

module DatabaseReaderTest =

  [<Test>]
  let ``Results are returned from database`` () =
    DatabaseReader.result.GetSqlString(1) |> should equal "first"

answered Oct 08 '11 at 15:48

Tomas Petricek

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@Carsten König: just use object expressions... I don't remember ever needing Moq / Rhino Mocks. – Mauricio Scheffer Oct 08 '11 at 17:01
well from time to time you need more than this but thank you anyway (problem is having a extented set of helper-extension-methods for Moq and reinventing the wheel :) ) – Random Dev Oct 08 '11 at 17:29
Yeah, I was intending to use the doubletick syntax, but this was really just a proof of concept to figure out FsUnit. Thanks for the tip about the more lightweight version. Object expressions seem like they would get to be a lot of work if mocking something complex, but that falls a bit outside of this discussion. Would love to hear more about that though. Any tips pointing to a thorough comparison of object expressions and mocking libraries? – McMuttons Oct 10 '11 at 12:42

When making a test class with FsUnit, [] is not a valid attribute on a member. Why?

2 Answers2