Allow running quicktest in --run-only (mostly for AI purpose) (#4430)

Author: MangelMaxime

CLAUDE.md

@@ -25,8 +25,8 @@ The build system is implemented in F# at `src/Fable.Build/`. All commands go thr
 ./build.sh test python --skip-fable-library-core  # Skip slow Rust extension + .pyi rebuild (Python only)
 ./build.sh test python --type-check               # Run Pyright type checking on Python output
 
-# Quick iteration (watch mode on a minimal project)
-./build.sh quicktest javascript                   # Also: typescript, python, dart, rust, beam
+# Quick iteration (test on a minimal project)
+./build.sh quicktest javascript --run-only        # Also: typescript, python, dart, rust, beam
 ```
 
 `--skip-fable-library` is safe when changes are only in `src/Fable.Transforms/` or other compiler code. If you modified runtime library source (e.g., `src/fable-library-py/`, `src/fable-library-ts/`), do not skip. If you already ran `./build.sh fable-library` separately, use `--skip-fable-library` when running tests right afterwards to avoid rebuilding.

src/Fable.Build/Quicktest/Core.fs

@@ -20,6 +20,7 @@ type QuicktestConfig =
 
 let genericQuicktest (config: QuicktestConfig) (args: string list) =
     let skipFableLibrary = args |> List.contains "--skip-fable-library"
+    let runOnly = args |> List.contains "--run-only"
 
     config.FableLibBuilder.Run(skipFableLibrary)
 
@@ -44,17 +45,19 @@ let genericQuicktest (config: QuicktestConfig) (args: string list) =
         workingDirectory = projectDir
     )
 
-    Command.WatchFableAsync(
+    let fableArgs =
         CmdLine.empty
         |> CmdLine.appendRaw projectDir
         |> CmdLine.appendPrefix "--lang" config.Language
         |> CmdLine.appendPrefix "--extension" config.Extension
         |> CmdLine.appendPrefix "--exclude" "Fable.Core"
         |> CmdLine.appendRaw "--noCache"
         |> CmdLine.appendRaw "--verbose"
-        |> CmdLine.appendRaw "--watch"
-        |> appendRunMode,
-        workingDirectory = projectDir
-    )
-    |> Async.AwaitTask
-    |> Async.RunSynchronously
+        |> appendRunMode
+
+    if runOnly then
+        Command.Fable(fableArgs, workingDirectory = projectDir)
+    else
+        Command.WatchFableAsync(fableArgs |> CmdLine.appendRaw "--watch", workingDirectory = projectDir)
+        |> Async.AwaitTask
+        |> Async.RunSynchronously