Run the snapshot comparison on CI (#56207)

Summary:

Changelog: [Internal]

Differential Revision: D96101927

Author: j-piasecki

.gitignore

@@ -183,5 +183,5 @@ __pycache__/
 # Doxygen XML output used for C++ API tracking
 /packages/react-native/**/api/xml
 /packages/react-native/**/api/codegen
-/packages/react-native/**/.doxygen.config.generated
+/packages/react-native/**/.doxygen.config.*.generated
 /scripts/cxx-api/codegen

scripts/cxx-api/api-snapshots/ReactAndroidDebugCxx.api

@@ -35,8 +35,12 @@ def run_command(
     """Run a subprocess command with consistent error handling."""
     result = subprocess.run(cmd, **kwargs)
     if result.returncode != 0:
-        if verbose:
-            print(f"{label} finished with error: {result.stderr}")
+        stderr_output = result.stderr or ""
+        if isinstance(stderr_output, bytes):
+            stderr_output = stderr_output.decode("utf-8", errors="replace")
+        print(f"{label} failed (exit code {result.returncode})", file=sys.stderr)
+        if stderr_output:
+            print(stderr_output, file=sys.stderr)
         raise RuntimeError(
             f"{label} finished with error (exit code {result.returncode})"
         )
@@ -53,9 +57,11 @@ def build_codegen(
 ) -> str:
     react_native_dir = os.path.join(get_react_native_dir(), "packages", "react-native")
 
+    node_bin = os.environ.get("NODE_BIN", "node")
+
     run_command(
         [
-            "node",
+            node_bin,
             "./scripts/generate-codegen-artifacts.js",
             "--path",
             "./",
@@ -227,6 +233,11 @@ def main():
         action="store_true",
         help="Generate snapshots to a temp directory and compare against committed ones",
     )
+    parser.add_argument(
+        "--check-output",
+        type=str,
+        help="File path to write check results to (used with --check)",
+    )
     parser.add_argument(
         "--snapshot-dir",
         type=str,
@@ -302,7 +313,11 @@ def main():
         if args.check:
             snapshot_dir = args.snapshot_dir or get_default_snapshot_dir()
 
-            if not check_snapshots(snapshot_output_dir, snapshot_dir):
+            if not check_snapshots(
+                snapshot_output_dir,
+                snapshot_dir,
+                output_file=args.check_output,
+            ):
                 sys.exit(1)
 
             print("All snapshot checks passed")

scripts/cxx-api/api-snapshots/ReactAndroidReleaseCxx.api

@@ -9,25 +9,40 @@
 
 import difflib
 import os
+import sys
 
 
-def check_snapshots(generated_dir: str, committed_dir: str) -> bool:
+def check_snapshots(
+    generated_dir: str, committed_dir: str, output_file: str | None = None
+) -> bool:
     """Compare generated snapshots against committed ones.
 
     Returns True if check passes (snapshots match or no committed snapshots).
     Returns False if snapshots differ.
+
+    If output_file is provided, writes comparison results to that file
+    instead of stdout.
     """
+    out = open(output_file, "w") if output_file else sys.stdout
+    try:
+        return _check_snapshots_impl(generated_dir, committed_dir, out)
+    finally:
+        if output_file:
+            out.close()
+
+
+def _check_snapshots_impl(generated_dir: str, committed_dir: str, out) -> bool:
     if not os.path.isdir(committed_dir):
-        print(f"No committed snapshots directory found at: {committed_dir}")
-        print("Skipping comparison (no baseline to compare against)")
+        print(f"No committed snapshots directory found at: {committed_dir}", file=out)
+        print("Skipping comparison (no baseline to compare against)", file=out)
         return True
 
     committed_files = sorted(f for f in os.listdir(committed_dir) if f.endswith(".api"))
     generated_files = sorted(f for f in os.listdir(generated_dir) if f.endswith(".api"))
 
     if not committed_files:
-        print("No committed snapshot files found")
-        print("Skipping comparison (no baseline to compare against)")
+        print("No committed snapshot files found", file=out)
+        print("Skipping comparison (no baseline to compare against)", file=out)
         return True
 
     committed_set = set(committed_files)
@@ -40,13 +55,14 @@ def check_snapshots(generated_dir: str, committed_dir: str) -> bool:
 
         if filename not in generated_set:
             print(
-                f"FAIL: {filename} exists in committed snapshots but was not generated"
+                f"FAIL: {filename} exists in committed snapshots but was not generated",
+                file=out,
             )
             all_passed = False
             continue
 
         if filename not in committed_set:
-            print(f"OK: {filename} generated (no committed baseline)")
+            print(f"OK: {filename} generated (no committed baseline)", file=out)
             continue
 
         with open(committed_path) as f:
@@ -55,9 +71,9 @@ def check_snapshots(generated_dir: str, committed_dir: str) -> bool:
             generated_content = f.read()
 
         if committed_content == generated_content:
-            print(f"OK: {filename} matches committed snapshot")
+            print(f"OK: {filename} matches committed snapshot", file=out)
         else:
-            print(f"FAIL: {filename} differs from committed snapshot")
+            print(f"FAIL: {filename} differs from committed snapshot", file=out)
             diff = "\n".join(
                 difflib.unified_diff(
                     committed_content.splitlines(),
@@ -67,7 +83,7 @@ def check_snapshots(generated_dir: str, committed_dir: str) -> bool:
                     lineterm="",
                 )
             )
-            print(diff)
+            print(diff, file=out)
             all_passed = False
 
     return all_passed