Introduce opentelemetry in rewatch and setup new test infrastructure

.github/workflows/ci.yml

@@ -324,18 +324,6 @@ jobs:
         if: runner.os != 'Windows'
         run: make -C tests/gentype_tests/typescript-react-example clean test
 
-      # On Windows, after running setup-ocaml (if it wasn't cached yet or the cache couldn't be restored),
-      # Cygwin bash is used instead of Git Bash for Windows, breaking the rewatch tests.
-      # So we need to adjust the path to bring back Git Bash for Windows.
-      - name: Rewatch tests need Git Bash for Windows
-        if: ${{ runner.os == 'Windows' }}
-        run: echo "C:\Program Files\Git\bin" >> $GITHUB_PATH
-        shell: bash
-
-      - name: Run rewatch tests
-        run: ./rewatch/tests/suite.sh rewatch/target/release/rescript
-        shell: bash
-
       - name: Run syntax benchmarks
         if: matrix.benchmarks
         run: |
@@ -645,15 +633,18 @@ jobs:
           # Run integration tests with the oldest supported node version.
           node-version: 20
 
-      - name: Install ReScript package in rewatch/testrepo
+      - name: Install npm packages
+        run: yarn install
+
+      - name: Install ReScript package in test fixture
         run: |
           COMMIT_SHA="${{ github.event.pull_request.head.sha || github.sha }}"
           yarn add "rescript@https://pkg.pr.new/rescript-lang/rescript@${COMMIT_SHA::7}"
         shell: bash
-        working-directory: rewatch/testrepo
+        working-directory: tests/rewatch_tests/fixture
 
       - name: Run rewatch integration tests
-        run: ./rewatch/tests/suite.sh rewatch/testrepo/node_modules/.bin/rescript
+        run: node scripts/test.js -rewatch
         shell: bash
 
   publish:

AGENTS.md

@@ -387,21 +387,7 @@ make test-rewatch     # Run integration tests
 
 **Note**: The rewatch project is located in the `rewatch/` directory with its own `Cargo.toml` file. All cargo commands should be run from the project root using the `--manifest-path rewatch/Cargo.toml` flag, as shown in the CI workflow.
 
-**Integration Tests**: The `make test-rewatch` command runs bash-based integration tests located in `rewatch/tests/suite.sh`. These tests use the `rewatch/testrepo/` directory as a test workspace with various package configurations to verify rewatch's behavior across different scenarios.
-
-**Running Individual Integration Tests**: You can run individual test scripts directly by setting up the environment manually:
-
-```bash
-cd rewatch/tests
-export REWATCH_EXECUTABLE="$(realpath ../target/debug/rescript)"
-eval $(node ./get_bin_paths.js)
-export RESCRIPT_BSC_EXE
-export RESCRIPT_RUNTIME
-source ./utils.sh
-bash ./watch/06-watch-missing-source-folder.sh
-```
-
-This is useful for iterating on a specific test without running the full suite.
+**Integration Tests**: The `make test-rewatch` command runs Vitest-based integration tests located in `tests/rewatch_tests/`. These tests use a sandbox copy of `tests/rewatch_tests/fixture/` to verify rewatch's behavior across different scenarios (build, watch, clean, format, etc.).
 
 #### Debugging
 
@@ -410,6 +396,26 @@ This is useful for iterating on a specific test without running the full suite.
 - **Dependencies**: Inspect module dependency graph in `deps.rs`
 - **File Watching**: Monitor file change events in `watcher.rs`
 
+#### OpenTelemetry Tracing
+
+Rewatch supports OpenTelemetry (OTEL) tracing for build and watch commands. To visualize traces locally, run a Jaeger all-in-one container:
+
+```bash
+docker run -d --name jaeger \
+  -p 4317:4317 -p 4318:4318 -p 16686:16686 \
+  jaegertracing/all-in-one
+```
+
+Then run rewatch with the OTLP endpoint set:
+
+```bash
+OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 cargo run --manifest-path rewatch/Cargo.toml -- build
+```
+
+Open http://localhost:16686 to view traces in the Jaeger UI.
+
+Note: Use `tracing::debug!` (not `log::debug!`) for events you want to appear in OTEL traces — they use separate logging systems.
+
 #### Running Rewatch Directly
 
 When running the rewatch binary directly (via `cargo run` or the compiled binary) during development, you need to set environment variables to point to the local compiler and runtime. Otherwise, rewatch will try to use the installed versions:
@@ -493,5 +499,3 @@ When clippy suggests refactoring that could impact performance, consider the tra
 ## CI Gotchas
 
 - **`sleep` is fragile** — Prefer polling (e.g., `wait_for_file`) over fixed sleeps. CI runners are slower than local machines.
-- **`exit_watcher` is async** — It only signals the watcher to stop (removes the lock file), it doesn't wait for the process to exit. Avoid triggering config-change events before exiting, as the watcher may start a concurrent rebuild.
-- **`sed -i` differs across platforms** — macOS requires `sed -i '' ...`, Linux does not. Use the `replace` / `normalize_paths` helpers from `rewatch/tests/utils.sh` instead of raw `sed`.

CHANGELOG.md

@@ -25,10 +25,12 @@
 #### :nail_care: Polish
 
 - Build system: Watch only source folders from build state instead of the entire project directory, and report missing configured source folders. https://github.com/rescript-lang/rescript/pull/8219
+- Build system: Add OpenTelemetry tracing support for cli commands. https://github.com/rescript-lang/rescript/pull/8241
 
 #### :house: Internal
 
 - speed up dev container test by installing ocaml in docker image instead of in `postCreate.sh`. https://github.com/rescript-lang/rescript/pull/8230
+- Migrate rewatch integration tests from bash scripts to Vitest and remove old test infrastructure. https://github.com/rescript-lang/rescript/pull/8241
 
 # 13.0.0-alpha.1
 

Makefile

@@ -174,7 +174,7 @@ test-gentype: lib
 	make -C tests/gentype_tests/stdlib-no-shims clean test
 
 test-rewatch: lib
-	./rewatch/tests/suite.sh $(RESCRIPT_EXE)
+	node scripts/test.js -rewatch
 
 test-all: test test-gentype test-analysis test-tools test-rewatch
 

biome.json

@@ -76,7 +76,8 @@
       "!**/package.json",
       "!**/packages/artifacts.json",
       "!**/.mypy_cache",
-      "!**/.history"
+      "!**/.history",
+      "!**/noop-ppx"
     ]
   }
 }

package.json

@@ -105,6 +105,7 @@
     "tests/gentype_tests/**",
     "tests/tools_tests",
     "tests/commonjs_tests",
+    "tests/rewatch_tests",
     "scripts/res"
   ],
   "packageManager": "yarn@4.12.0",