Testing And Benchmarking in Elm

Here’s the translation of the Go testing and benchmarking example to Elm, formatted in Markdown suitable for Hugo:

In Elm, testing is typically done using the elm-test package. While Elm doesn’t have built-in benchmarking tools like Go, we can still demonstrate the testing concepts. Here’s how we might approach testing in Elm:

First, let’s define our function to be tested in a file called IntUtils.elm:

module IntUtils exposing (intMin)

intMin : Int -> Int -> Int
intMin a b =
    if a < b then
        a
    else
        b

Now, let’s create our test file, tests/IntUtilsTest.elm:

module IntUtilsTest exposing (..)

import Expect exposing (Expectation)
import Fuzz exposing (Fuzzer, int, list)
import IntUtils exposing (intMin)
import Test exposing (..)

intMinTest : Test
intMinTest =
    describe "IntUtils.intMin"
        [ test "returns the smaller of two positive integers" <|
            \_ ->
                Expect.equal 2 (intMin 2 4)
        , test "returns the smaller of two negative integers" <|
            \_ ->
                Expect.equal -4 (intMin -2 -4)
        , test "returns the negative integer when comparing positive and negative" <|
            \_ ->
                Expect.equal -2 (intMin 2 -2)
        ]

intMinTableTest : Test
intMinTableTest =
    describe "IntUtils.intMin (table driven)"
        [ Test.describe "intMin"
            (List.map
                (\( a, b, expected ) ->
                    test (String.fromInt a ++ "," ++ String.fromInt b) <|
                        \_ ->
                            Expect.equal expected (intMin a b)
                )
                [ ( 0, 1, 0 )
                , ( 1, 0, 0 )
                , ( 2, -2, -2 )
                , ( 0, -1, -1 )
                , ( -1, 0, -1 )
                ]
            )
        ]

In this Elm test file:

1. We import necessary testing modules and our IntUtils module.
2. We define intMinTest, which is similar to the TestIntMinBasic in the Go example.
3. We also define intMinTableTest, which is analogous to the table-driven test in Go.

To run these tests, you would typically use the elm-test command:

$ elm-test

This would run all the tests in your project and provide output similar to:

elm-test 0.19.1-revision9
-------------------------

Running 6 tests. To reproduce these results, run: elm-test --fuzz 100 --seed 123456

TEST RUN PASSED

Duration: 185 ms
Passed:   6
Failed:   0

Note that Elm doesn’t have a built-in benchmarking tool like Go’s. For performance testing in Elm, you might need to use browser-based tools or create custom timing functions.

Remember to install the necessary packages (elm-test and elm-explorations/test) before running the tests.

While the concepts are similar, Elm’s approach to testing is more focused on unit tests and property-based testing (via fuzz testing) rather than benchmarking. The ecosystem and tooling around testing in Elm reflect its primary use case as a language for web front-end development.