✨ add before and after hooks

Author: jakubsob

NAMESPACE

@@ -1,5 +1,7 @@
 # Generated by roxygen2: do not edit by hand
 
+export(after)
+export(before)
 export(define_parameter_type)
 export(given)
 export(test)
@@ -13,6 +15,7 @@ importFrom(checkmate,assert_list)
 importFrom(checkmate,assert_string)
 importFrom(checkmate,assert_subset)
 importFrom(checkmate,test_character)
+importFrom(checkmate,test_subset)
 importFrom(dplyr,bind_cols)
 importFrom(fs,dir_ls)
 importFrom(glue,glue)
@@ -27,6 +30,7 @@ importFrom(purrr,set_names)
 importFrom(purrr,walk)
 importFrom(rlang,`:=`)
 importFrom(rlang,abort)
+importFrom(rlang,arg_match)
 importFrom(rlang,call2)
 importFrom(rlang,call_modify)
 importFrom(rlang,exec)

R/hooks.R

@@ -0,0 +1,89 @@
+#' @importFrom rlang abort
+make_hook <- function(name) {
+  function(hook) {
+    if (length(formals(hook)) != 2) {
+      abort(
+        message = "Hook must have two arguments.",
+        body = "The first argument is the context and the second is the scenario name."
+      )
+    }
+    register_hook(hook, name)
+    invisible(hook)
+  }
+}
+
+#' Hooks
+#'
+#' Hooks are functions that are run before or after a scenario.
+#'
+#' You can define them alongside steps definitions.
+#'
+#' If you want to run a hook only before or after a specific scenario, use it's name to execute hook only for this scenario.
+#'
+#' @param hook A function that will be run. The function first argument is context and the scenario name is the second argument.
+
+#' @examples
+#' \dontrun{
+#' before(function(context, scenario_name) {
+#'   context$session <- selenider::selenider_session()
+#' })
+#'
+#' after(function(context, scenario_name) {
+#'   selenider::close_session(context$session)
+#' })
+#'
+#' after(function(context, scenario_name) {
+#'   if (scenario_name == "Playing one round of the game") {
+#'     context$game$close()
+#'   }
+#' })
+#' }
+#' @md
+#' @name hook
+NULL
+
+#' @rdname hook
+#' @export
+before <- make_hook("before")
+
+#' @rdname hook
+#' @export
+after <- make_hook("after")
+
+#' @importFrom rlang list2
+.hooks <- function(...) {
+  structure(list2(...), class = "hooks")
+}
+
+#' @importFrom rlang `:=` arg_match abort
+#' @importFrom checkmate test_subset
+#' @importFrom glue glue
+register_hook <- function(
+  hook,
+  name = c("before", "after")
+) {
+  arg_match(name)
+  hooks <- getOption(".cucumber_hooks", default = .hooks())
+  if (test_subset(name, names(hooks))) {
+    abort(
+      message = glue("Hook '{name}' already registered."),
+      body = "A hook can only be registered once."
+    )
+  }
+  hooks <- .hooks(!!name := hook)
+  options(.cucumber_hooks = hooks)
+  invisible(hooks)
+}
+
+#' @importFrom purrr pluck
+get_hook <- function(hooks = get_hooks(), name) {
+  pluck(hooks, name, .default = function(...) { })
+}
+
+clear_hooks <- function() {
+  options(.cucumber_hooks = .hooks())
+}
+
+get_hooks <- function() {
+  getOption(".cucumber_hooks", default = .hooks())
+}

R/parse_token.R

@@ -2,7 +2,13 @@
 #' @importFrom glue glue
 #' @importFrom purrr map walk
 #' @importFrom testthat context_start_file test_that
-parse_token <- function(tokens, steps, parameters = get_parameters()) {
+parse_token <- function(
+  tokens,
+  steps,
+  parameters = get_parameters(),
+  hooks = get_hooks()
+) {
+  force(hooks)
   map(tokens, \(token) {
     switch(
       token$type,
@@ -13,17 +19,19 @@ parse_token <- function(tokens, steps, parameters = get_parameters()) {
             calls <- parse_token(token$children, steps, parameters) |>
               map(\(x) call_modify(x, context = context))
 
+            get_hook(hooks, "before")(context, token$value)
             # Use `for` for better error messages instead of purrr indexed ones
             for (call in calls) {
               eval(call)
             }
+            get_hook(hooks, "after")(context, token$value)
           })
         }
       ),
       "Feature" = call2(
         function(file_name = token$value) {
           context_start_file(glue("Feature: {file_name}"))
-          parse_token(token$children, steps, parameters) |>
+          parse_token(token$children, steps, parameters, hooks) |>
             walk(eval)
         }
       ),

R/run.R

@@ -2,9 +2,10 @@
 run <- function(
   feature,
   steps,
-  parameters = get_parameters()
+  parameters = get_parameters(),
+  hooks = get_hooks()
 ) {
   tokens <- tokenize(feature)
-  call_queue <- parse_token(tokens, steps, parameters)
+  call_queue <- parse_token(tokens, steps, parameters, hooks)
   walk(call_queue, eval)
 }

R/test.R

@@ -37,6 +37,7 @@ test <- function(
   assert_function(steps_loader, nargs = 1)
   defer({
     clear_steps()
+    clear_hooks()
     set_default_parameters()
   })
   steps <- steps_loader(steps_dir)

inst/examples/hooks/tests/testthat/hooks.feature

@@ -0,0 +1,4 @@
+Feature: Hooks
+  Scenario: Before hook is executed
+    When I start the scenario
+    Then the before hook was run

inst/examples/hooks/tests/testthat/steps/steps.R

@@ -0,0 +1,11 @@
+before(function(context, name) {
+  context$before <- TRUE
+})
+
+when("I start the scenario", function(context) {
+
+})
+
+then("the before hook was run", function(context) {
+  expect_true(context$before)
+})

inst/examples/hooks/tests/testthat/test-cucumber.R

@@ -0,0 +1 @@
+cucumber::test(".", "./steps")

man/hook.Rd

@@ -88,6 +88,17 @@
       == Results =====================================================================
       [ FAIL 0 | WARN 0 | SKIP 0 | PASS 2 ]
 
+# test: should run before hook
+
+    Code
+      testthat::test_dir(tests_path, reporter = testthat::ProgressReporter$new(
+        show_praise = FALSE), stop_on_failure = FALSE)
+    Output
+      v | F W  S  OK | Context
+      v |          1 | Feature: Hooks
+      == Results =====================================================================
+      [ FAIL 0 | WARN 0 | SKIP 0 | PASS 1 ]
+
 # test: should run a Scenario with custom parameters
 
     Code