split out a task for running dune exec and add env param in p_run

src/common/p_run.ml

@@ -82,11 +82,29 @@ let pp_result ?(hide_stdout = false) ?(hide_stderr = false) ?command_line ppf r
     (option (cut ++ pp_output "STDERR"))
     (if hide_stderr then None else Some r.stderr)
 
+let build_env =
+  let f (k, v) =
+    if String.contains k '=' then
+      raise (Invalid_argument "illegal '=' in environment variable name")
+    else if String.contains k '\000' then
+      raise (Invalid_argument "illegal '\\000' in environment variable name")
+    else if k = "" then
+      raise (Invalid_argument "empty environment variable name")
+    else String.concat "=" [k; v]
+  in
+  List.map f
+
 (** Send the [input] to [command] with the given [args].
     Note: uses temporary files provided by {!Filename}. *)
-let p_run ?timeout:timeout_desc ?input ?(args = []) command =
+let p_run ?timeout:timeout_desc ?input ?(args = []) ?(env = []) command =
   let open Ctx_util in
 
+  let env =
+    Array.append
+      (Unix.environment ())
+      (Array.of_list @@ build_env env)
+  in
+
   let< stdout_path = temp_file command "stdout" in
   let< stderr_path = temp_file command "stderr" in
 
@@ -105,8 +123,8 @@ let p_run ?timeout:timeout_desc ?input ?(args = []) command =
     let t0 = Mtime_clock.counter () in
 
     let pid =
-      Unix.create_process command
-        (Array.of_list (command :: args))
+      Unix.create_process_env command
+        (Array.of_list (command :: args)) env
         stdin_fd stdout_fd stderr_fd
     in
 

src/test-runner/std_task.ml

@@ -3,6 +3,7 @@
 open Task
 open Common
 open Ctx_util
+open Util
 
 let f = Printf.sprintf
 
@@ -130,8 +131,8 @@ let checker cfg ?prohibited ?(limit = 3) ?check1 ?check p =
         failf "%a" buffer buff
 
 (** Run a process as a task *)
-let subprocess_run ?timeout ?args command =
-  task1 @@ fun _ -> P_run.p_run ?timeout ?args command
+let subprocess_run ?timeout ?args ?env command =
+  task1 @@ fun _ -> P_run.p_run ?timeout ?args ?env command
 
 (** Handle the result of a subprocess task. *)
 let subprocess_result ?hide_stdout ?hide_stderr
@@ -167,8 +168,8 @@ let subprocess_options ?timeout ?(hide_stdout = false) ?(hide_stderr = false)
     ?error_message ?(check_status = true) ?(dump_output = true) () =
   { timeout; hide_stdout; hide_stderr; error_message; check_status; dump_output }
 
-let subprocess cfg ?(options = subprocess_options ()) ?args command =
-  let run = subprocess_run ?timeout:options.timeout ?args command in
+let subprocess cfg ?(options = subprocess_options ()) ?args ?env command =
+  let run = subprocess_run ?timeout:options.timeout ?args ?env command in
   let result =
     subprocess_result ()
       ~hide_stdout:(options.hide_stdout && cfg.safe)
@@ -180,8 +181,8 @@ let subprocess cfg ?(options = subprocess_options ()) ?args command =
   in
   group (run |> then_ result)
 
-let dune cfg ?options ~root ?(args = []) cmd =
-  subprocess cfg ?options "opam"
+let dune cfg ?options ~root ?(args = []) ?env cmd =
+  subprocess cfg ?options "opam" ?env
     ~args:([
         "exec"; "--"; "dune"; cmd;
         "--no-print-directory";
@@ -194,7 +195,12 @@ let timeout_for cfg = function
   | `Probe -> cfg.probe_timeout
 
 
-(** {1 Standard tasks} *)
+(** {1 Standard tasks}
+
+    These are high-level tasks built upon the primitives defined above.
+    They work with the recommended layout of tests, submission and sample
+    solution. However, the low-level tasks defined above can also be used
+    as needed. *)
 
 let std_test_report_dir = "test-reports/"
 
@@ -225,18 +231,36 @@ let std_check cfg = checker cfg "tests/assignment"
 
 (** Build something in the [tests/] directory with dune.
     If [submission] is [false] (default), error output is hidden. *)
-let std_build1 cfg ?(submission = false) what =
-  ignore @@
-  dune cfg
-    ~options:(
-      subprocess_options ()
-        ~timeout:(P_run.timeout (timeout_for cfg `Build))
-        ~hide_stdout:(not submission) ~hide_stderr:(not submission)
-        ~error_message:Messages.(
-          if submission then submission_error else test_failure))
-    ~root:"tests/" "build" ~args:["--force"; what]
-
-(* Build the assignment library and test binary. *)
+let std_build1 cfg ?(submission = false) ?env what =
+  let options =
+    subprocess_options ()
+      ~timeout:(P_run.timeout (timeout_for cfg `Build))
+      ~hide_stdout:(not submission) ~hide_stderr:(not submission)
+      ~error_message:Messages.(
+        if submission then submission_error else test_failure)
+  in
+  dune cfg ~options ~root:"tests/"
+    "build" ~args:["--force"; what] ?env
+  |> ignore
+
+(** Run something in the [tests/] directory with [dune exec].
+
+    This task passes the [--no-build] flag to dune. As such:
+    - The executable must be built before
+      running this task (e.g. with {!std_build1}).
+    - There is no risk of showing the build output to the student.
+
+    If [phase] is given, sets a timeout. *)
+let std_exec1 cfg ?phase ?(args = []) ?env what =
+  let options =
+    subprocess_options ()
+      ?timeout:(phase |> Option.map (timeout_for cfg %> P_run.timeout))
+  in
+  dune cfg ~options ~root:"tests/"
+    "exec" ~args:(["--no-build"; "--"; what] @ args) ?env
+  |> ignore
+
+(** Build the assignment library and test binary. *)
 let std_build cfg = group ~label:"build" @@ of_list [
   (* First, build only the student submission without referencing the tests
       or the solution, so that we can show the build output to the student
@@ -251,35 +275,34 @@ let std_build cfg = group ~label:"build" @@ of_list [
   std_build1 cfg ~submission:false "test" |> with_ ~label:"test";
 ]
 
-(** Run the generated binary. *)
-let std_test cfg = group ~label:"test" @@ of_list [
-  (* The test executable is configured to exit immediately if no arguments are passed.
-      We use this to check that the top level code of the submission does not
-      contain any long-running code. If it does, there's no point in running the tests,
-      since the significantly longer test timeout will just kill them.
-      We don't want to prohibit top-level code entirely, since it would prevent
-      things like [let impl0 = impl 0] *)
-  dune cfg
-    ~options:(
-      subprocess_options ()
-        ~timeout:(P_run.timeout (timeout_for cfg `Probe)))
-    ~root:"tests/" "exec" ~args:["--no-build"; "--"; "test/test.exe"]
-  |> ignore |> with_ ~label:"top_level";
-  (* note: the 'probe' name here is unrelated to the
-      partial signature checking probe below *)
+(** Run a test executable in the standard setup. See the note about building
+    first in {!std_exec1}. Assumes the test executable is configured to exit
+    immediately if no command line arguments are passed.
+    We use this to check that the top level code of the submission does not
+    contain any long-running code. If it does, there's no point in running the
+    tests, since the significantly longer test timeout will just kill them.
+    We don't want to prohibit top-level code entirely, since it would prevent
+    things like [let impl0 = impl 0].
+
+    Thus, first runs the given executable without any arguments, then runs it a
+    second time, passing the given path as the output JUnit file. *)
+let std_exec_test cfg ?env ~output_junit_file what = group @@ of_list [
+  (* Note: the 'probe' name here is unrelated to the partial signature
+     checking probe below, and refers to the top-level check *)
+  std_exec1 cfg ~phase:`Probe ?env what |> with_ ~label:"top_level";
 
   (* run the test! *)
-  dune cfg
-    ~options:(
-      subprocess_options ()
-        ~timeout:(P_run.timeout (timeout_for cfg `Test)))
-    ~root:"tests/" "exec"
-    ~args:[
-      "--no-build"; "--"; "test/test.exe";
-      "-output-junit-file"; "test-reports/results.xml"]
-  |> ignore |> with_ ~label:"run";
+  std_exec1 cfg ~phase:`Test ?env what
+    ~args:["-output-junit-file"; output_junit_file]
+  |> with_ ~label:"run";
 ]
 
+(** As {!std_exec_test}, fixed to [test/test.exe]
+    with output to [test-reports/results.xml]. *)
+let std_test cfg =
+  std_exec_test cfg "test/test.exe"
+    ~output_junit_file:"test-reports/results.xml"
+  |> with_ ~label:"test"
 
 (** {1 Probe-related tasks (partial type correctness checking)} *)