F# Scripting

Napper supports F# Interactive scripts (.fsx files) for pre/post request hooks and test orchestration. This gives you the full power of .NET for complex testing scenarios.

Pre/post request hooks

Reference scripts in your .nap file:

[script]
pre = ./scripts/setup-auth.fsx
post = ./scripts/validate-response.fsx

Pre-request scripts

Run before the HTTP request is sent. Use them to set up authentication, generate dynamic data, or modify variables.

// setup-auth.fsx
let token = generateToken ()
ctx.Set "token" token
ctx.Log $"Token generated: {token.[..8]}..."

Post-request scripts

Run after the response is received. Use them for complex validation, data extraction, or chaining.

// validate-response.fsx
let body = ctx.Response.Json

// Extract and pass to next step
let userId = body.GetProperty("id").GetInt32()
ctx.Set "userId" (string userId)

// Complex validation
if userId <= 0 then
    ctx.Fail "User ID must be positive"

ctx.Log $"Created user {userId}"

NapContext

Scripts receive a ctx object with these members:

Orchestration scripts

For complex flows, use orchestration scripts that control execution directly:

// orchestration.fsx

// Run a request and get the result
let loginResult = runner.Run "./auth/login.nap"

// Extract token from response
let token = loginResult.Response.Json.GetProperty("token").GetString()
runner.Vars.["token"] <- token

// Run a suite of tests with the token
let results = runner.RunList "./crud-tests.naplist"

// Data-driven testing
for userId in [1; 2; 3; 42; 99] do
    runner.Vars.["userId"] <- string userId
    let result = runner.Run "./users/get-user.nap"
    if result.Failed then
        runner.Log $"Failed for user {userId}: {result.Error}"

Reference orchestration scripts in a .naplist:

[steps]
./scripts/orchestration.fsx

NapRunner

Orchestration scripts receive a runner object:

Requirements

F# scripts require the .NET 10 SDK installed on the machine. The Napper CLI binary itself is self-contained, but .fsx scripts are executed via F# Interactive.