FSharp.Data.SqlClient/docs/content/unit-testing.fsx at 27e6ef687dba09dde4421ab72bf55de6be5aaef8 · Thorium/FSharp.Data.SqlClient · GitHub

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(*** hide ***)
#r @"..\..\bin\net462\FSharp.Data.SqlClient.dll"
#r @"..\..\packages\Test\xunit\lib\net20\xunit.dll"
#r "System.Transactions"
open FSharp.Data
open System

[<Literal>]
let connectionString = @"Data Source=.;Initial Catalog=AdventureWorks2012;Integrated Security=True;TrustServerCertificate=true"

(**

Unit-testing
===================

Often there is a need to test business or presentation logic independently of database.
This can be archived via [Repository](http://martinfowler.com/eaaCatalog/repository.html) pattern.

*)

//Command types definitions
type GetEmployeesByLevel =
    SqlCommandProvider<"
        SELECT P.FirstName, P.LastName, E.JobTitle
        FROM HumanResources.Employee AS E
	        JOIN Person.Person AS P ON E.BusinessEntityID = P.BusinessEntityID
        WHERE OrganizationLevel = @orgLevel
    ", connectionString>

type GetSalesChampion = SqlCommandProvider<"
    SELECT TOP 1 FirstName, LastName
    FROM Sales.vSalesPerson
    WHERE CountryRegionName = @countryRegionName
    ORDER BY SalesYTD DESC
    " , connectionString, SingleRow = true>

//Repository inteface
type IRepository =
    abstract GetEmployeesByLevel: int16 -> list<GetEmployeesByLevel.Record>
    abstract GetSalesChampion: country: string -> option<GetSalesChampion.Record>

//Production implementation
type Repository(connectionString: string) =
    interface IRepository with
        member __.GetEmployeesByLevel(orgLevel) =
            use cmd = new GetEmployeesByLevel(connectionString)
            cmd.Execute(orgLevel) |> Seq.toList

        member __.GetSalesChampion( region) =
            use cmd = new GetSalesChampion(connectionString)
            cmd.Execute(region)

//logic to test
let whoReportsToCEO(db: IRepository) =
    [ for x in db.GetEmployeesByLevel(1s) -> sprintf "%s %s" x.FirstName x.LastName, x.JobTitle ]

let bestSalesRepInCanada(db: IRepository) =
    db.GetSalesChampion("Canada")

//unit tests suite
module MyTests =

    //mock the real repo
    let mockRepository = {
        new IRepository with
            member __.GetEmployeesByLevel(orgLevel) =
                if orgLevel = 1s
                then
                    [
                        //Generated record types have single constructor that include all properties
                        //It exists to support unit-testing.
                        GetEmployeesByLevel.Record("David", "Bradley", JobTitle = "Marketing Manager")
                    ]
                else []

            member __.GetSalesChampion( region) =
                use cmd = new GetSalesChampion(connectionString)
                cmd.Execute(region)
    }

    //unit test
    let ``who reports to CEO``() =
        let expected = [ "David Bradley", "Marketing Manager" ]
        assert (whoReportsToCEO mockRepository = expected)
        //replace assert invocation above with invocation to your favorite unit testing framework
        //fro example Xunit.NET: Assert.Equal<_ list>(expected, actual)

    //unit test
    let ``best sales rep in Canada``() =
        let expected = Some( GetSalesChampion.Record("José", "Saraiva"))
        assert (bestSalesRepInCanada mockRepository = expected)