From 130a2592f1e946be563c7f167d7127f49a1014d1 Mon Sep 17 00:00:00 2001
From: Luca Casonato <hello@lcas.dev>
Date: Wed, 14 Aug 2024 15:21:11 +0200
Subject: [PATCH] fix(cli): support --watch when running cjs npm packages
 (#25038)

---
 cli/args/mod.rs                    |  2 --
 cli/worker.rs                      | 17 +++++++++++++-
 tests/integration/watcher_tests.rs | 37 ++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 3 deletions(-)

diff --git a/cli/args/mod.rs b/cli/args/mod.rs
index 0f6f050efe..65f9183d5c 100644
--- a/cli/args/mod.rs
+++ b/cli/args/mod.rs
@@ -1151,8 +1151,6 @@ impl CliOptions {
               resolve_url_or_path("./$deno$stdin.ts", &cwd)
                 .map_err(AnyError::from)
             })?
-        } else if run_flags.watch.is_some() {
-          resolve_url_or_path(&run_flags.script, self.initial_cwd())?
         } else if NpmPackageReqReference::from_str(&run_flags.script).is_ok() {
           ModuleSpecifier::parse(&run_flags.script)?
         } else {
diff --git a/cli/worker.rs b/cli/worker.rs
index 8673804ab0..82051da6ce 100644
--- a/cli/worker.rs
+++ b/cli/worker.rs
@@ -280,7 +280,22 @@ impl CliMainWorker {
       /// Execute the given main module emitting load and unload events before and after execution
       /// respectively.
       pub async fn execute(&mut self) -> Result<(), AnyError> {
-        self.inner.execute_main_module_possibly_with_npm().await?;
+        if self.inner.is_main_cjs {
+          deno_node::load_cjs_module(
+            &mut self.inner.worker.js_runtime,
+            &self
+              .inner
+              .main_module
+              .to_file_path()
+              .unwrap()
+              .to_string_lossy(),
+            true,
+            self.inner.shared.options.inspect_brk,
+          )?;
+        } else {
+          self.inner.execute_main_module_possibly_with_npm().await?;
+        }
+
         self.inner.worker.dispatch_load_event()?;
         self.pending_unload = true;
 
diff --git a/tests/integration/watcher_tests.rs b/tests/integration/watcher_tests.rs
index 3cec2f442b..6203a62d96 100644
--- a/tests/integration/watcher_tests.rs
+++ b/tests/integration/watcher_tests.rs
@@ -3,6 +3,7 @@
 use flaky_test::flaky_test;
 use test_util as util;
 use test_util::assert_contains;
+use test_util::env_vars_for_npm_tests;
 use test_util::TempDir;
 use tokio::io::AsyncBufReadExt;
 use util::DenoChild;
@@ -707,6 +708,42 @@ async fn run_watch_no_dynamic() {
   check_alive_then_kill(child);
 }
 
+#[flaky_test(tokio)]
+async fn run_watch_npm_specifier() {
+  let _g = util::http_server();
+  let t = TempDir::new();
+
+  let file_to_watch = t.path().join("file_to_watch.txt");
+  file_to_watch.write("Hello world");
+
+  let mut child = util::deno_cmd()
+    .current_dir(t.path())
+    .envs(env_vars_for_npm_tests())
+    .arg("run")
+    .arg("--watch=file_to_watch.txt")
+    .arg("-L")
+    .arg("debug")
+    .arg("npm:@denotest/bin/cli-cjs")
+    .arg("Hello world")
+    .env("NO_COLOR", "1")
+    .piped_output()
+    .spawn()
+    .unwrap();
+  let (mut stdout_lines, mut stderr_lines) = child_lines(&mut child);
+
+  wait_contains("Hello world", &mut stdout_lines).await;
+  wait_for_watcher("file_to_watch.txt", &mut stderr_lines).await;
+
+  // Change content of the file
+  file_to_watch.write("Hello world2");
+
+  wait_contains("Restarting", &mut stderr_lines).await;
+  wait_contains("Hello world", &mut stdout_lines).await;
+  wait_for_watcher("file_to_watch.txt", &mut stderr_lines).await;
+
+  check_alive_then_kill(child);
+}
+
 // TODO(bartlomieju): this test became flaky on macOS runner; it is unclear
 // if that's because of a bug in code or the runner itself. We should reenable
 // it once we upgrade to XL runners for macOS.