Testing And Benchmarking in Standard ML

Here’s an idiomatic Standard ML example demonstrating the concept of testing and benchmarking:

(* intmin.sml *)

(* Simple implementation of integer minimum *)
fun intMin (a: int) (b: int): int =
    if a < b then a else b

(* Test structure *)
structure IntMinTest =
struct
    open SMLUnit.Test

    (* Basic test case *)
    fun testIntMinBasic () =
        assertEqual Int.toString (-2) (intMin 2 (~2))

    (* Table-driven test *)
    fun testIntMinTableDriven () =
        let
            val testCases = [
                (0, 1, 0),
                (1, 0, 0),
                (2, ~2, ~2),
                (0, ~1, ~1),
                (~1, 0, ~1)
            ]
            
            fun runTest (a, b, expected) =
                assertEqual Int.toString expected (intMin a b)
        in
            List.app runTest testCases
        end

    (* Benchmark function *)
    fun benchmarkIntMin () =
        let
            fun loop 0 = ()
              | loop n = (intMin 1 2; loop (n-1))
        in
            loop 1000000  (* Adjust this number based on your needs *)
        end

    (* Test suite *)
    val suite = "IntMin" >::: [
        "testIntMinBasic" >:: testIntMinBasic,
        "testIntMinTableDriven" >:: testIntMinTableDriven
    ]
end

(* Run the tests *)
val _ = SMLUnit.TextUITestRunner.runTest IntMinTest.suite

This example demonstrates testing and benchmarking in Standard ML, inspired by the Go example. Here’s a breakdown of the code:

1. We define a simple intMin function that returns the minimum of two integers.

2. We create a test structure IntMinTest that contains our test cases and benchmark function.

3. testIntMinBasic is a simple test case that checks if intMin 2 (~2) returns -2.

4. testIntMinTableDriven implements a table-driven test approach, similar to the Go example. It defines a list of test cases and runs each one.

5. benchmarkIntMin is a simple benchmark function that calls intMin multiple times.

6. We define a test suite that combines our test cases.

7. Finally, we run the tests using SMLUnit.TextUITestRunner.runTest.

To run this code:

1. Save it in a file named intmin.sml.
2. Make sure you have SML/NJ and SMLUnit installed.
3. Compile and run the code:

$ sml intmin.sml

This will execute the tests and display the results.

Note that Standard ML doesn’t have built-in benchmarking tools like Go does. The benchmarkIntMin function is a simple simulation of benchmarking. For more accurate benchmarking, you might need to use external tools or implement more sophisticated timing mechanisms.

Also, the testing framework used here (SMLUnit) is a third-party library and may not be as feature-rich as Go’s built-in testing package. However, it provides similar functionality for writing and running unit tests in Standard ML.