Fix equals syntax for accelerate config

tests/test_accelerate_config.py

@@ -0,0 +1,36 @@
+# Copyright 2020-2026 The HuggingFace Team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from pathlib import Path
+
+import pytest
+
+from trl.cli.accelerate_config import resolve_accelerate_config_argument
+
+
+@pytest.mark.parametrize(
+    "config_argument", [["--accelerate_config", "single_gpu"], ["--accelerate_config=single_gpu"]]
+)
+def test_resolve_packaged_accelerate_config(config_argument):
+    launch_args = resolve_accelerate_config_argument([*config_argument, "--num_processes", "2"])
+
+    assert launch_args[0] == "--config_file"
+    assert Path(launch_args[1]).name == "single_gpu.yaml"
+    assert launch_args[2:] == ["--num_processes", "2"]
+
+
+@pytest.mark.parametrize("config_argument", ["--accelerate_config", "--accelerate_config="])
+def test_resolve_accelerate_config_requires_value(config_argument):
+    with pytest.raises(ValueError, match="Expected a value"):
+        resolve_accelerate_config_argument([config_argument])

trl/cli/accelerate_config.py

@@ -23,14 +23,22 @@ def resolve_accelerate_config_argument(launch_args: list[str]) -> list[str]:
     The function supports either a filesystem path or a predefined config name shipped in `trl/accelerate_configs`
     (without the `.yaml` suffix).
     """
-    if "--accelerate_config" not in launch_args:
+    for config_index, argument in enumerate(launch_args):
+        if argument == "--accelerate_config":
+            if config_index + 1 >= len(launch_args):
+                raise ValueError("Expected a value after `--accelerate_config`.")
+            config_name = launch_args[config_index + 1]
+            argument_count = 2
+            break
+        if argument.startswith("--accelerate_config="):
+            config_name = argument.split("=", 1)[1]
+            if not config_name:
+                raise ValueError("Expected a value after `--accelerate_config`.")
+            argument_count = 1
+            break
+    else:
         return launch_args
 
-    config_index = launch_args.index("--accelerate_config")
-    if config_index + 1 >= len(launch_args):
-        raise ValueError("Expected a value after `--accelerate_config`.")
-
-    config_name = launch_args[config_index + 1]
     if Path(config_name).is_file():
         accelerate_config_path = config_name
     else:
@@ -42,6 +50,6 @@ def resolve_accelerate_config_argument(launch_args: list[str]) -> list[str]:
             )
         accelerate_config_path = candidate
 
-    # Remove '--accelerate_config <value>'.
-    launch_args = launch_args[:config_index] + launch_args[config_index + 2 :]
+    # Remove '--accelerate_config <value>' or '--accelerate_config=<value>'.
+    launch_args = launch_args[:config_index] + launch_args[config_index + argument_count :]
     return ["--config_file", str(accelerate_config_path)] + launch_args