ci: Pass CLI Arguments to workers with a pytest fixture (#3605)

Signed-off-by: Krishnan Prashanth <kprashanth@nvidia.com>

tests/unit/conftest.py

@@ -8,6 +8,9 @@ frameworks are not installed in the current container.
 """
 
 import importlib.util
+import sys
+
+import pytest
 
 
 def pytest_ignore_collect(collection_path, config):
@@ -30,3 +33,45 @@ def pytest_ignore_collect(collection_path, config):
                 return True  # Module not available, skip this file
 
     return None  # Not a backend test or module available
+
+
+def make_cli_args_fixture(module_name: str):
+    """Create a pytest fixture for mocking CLI arguments for a backend.
+
+    The returned fixture supports two call styles:
+
+    1. Explicit:
+        mock_vllm_cli("--model", "gpt-2", "--custom-jinja-template", "path.jinja")
+
+    2. Kwargs (auto-converts underscores to hyphens):
+        mock_vllm_cli(model="gpt-2", custom_jinja_template="path.jinja")
+
+    Both produce: ["dynamo.vllm", "--model", "gpt-2", "--custom-jinja-template", "path.jinja"]
+
+    Args:
+        module_name: Module identifier for argv[0] (e.g., "dynamo.vllm")
+
+    Returns:
+        Pytest fixture that mocks sys.argv via monkeypatch
+    """
+
+    @pytest.fixture
+    def mock_cli_args(monkeypatch):
+        """Mock sys.argv with CLI arguments (explicit or kwargs style)."""
+
+        def set_args(*args, **kwargs):
+            if args:
+                # Explicit style: pass argv elements directly
+                argv = [module_name, *args]
+            else:
+                # Kwargs style: convert python arg to CLI arg
+                argv = [module_name]
+                for param_name, param_value in kwargs.items():
+                    cli_flag = f"--{param_name.replace('_', '-')}"
+                    argv.extend([cli_flag, str(param_value)])
+
+            monkeypatch.setattr(sys, "argv", argv)
+
+        return set_args
+
+    return mock_cli_args

tests/unit/test_sglang_unit.py

@@ -10,6 +10,7 @@ from pathlib import Path
 import pytest
 
 from dynamo.sglang.args import parse_args
+from tests.unit.conftest import make_cli_args_fixture
 
 # Get path relative to this test file
 TEST_DIR = Path(__file__).parent.parent
@@ -23,19 +24,16 @@ pytestmark = [
 ]
 
 
-def test_custom_jinja_template_invalid_path(monkeypatch):
+# Create SGLang-specific CLI args fixture
+# This will use monkeypatch to write to argv
+mock_sglang_cli = make_cli_args_fixture("dynamo.sglang")
+
+
+def test_custom_jinja_template_invalid_path(mock_sglang_cli):
     """Test that invalid file path raises FileNotFoundError."""
     invalid_path = "/nonexistent/path/to/template.jinja"
-    monkeypatch.setattr(
-        sys,
-        "argv",
-        [
-            "dynamo.sglang",
-            "--model-path",
-            "Qwen/Qwen3-0.6B",
-            "--custom-jinja-template",
-            invalid_path,
-        ],
+    mock_sglang_cli(
+        "--model", "Qwen/Qwen3-0.6B", "--custom-jinja-template", invalid_path
     )
 
     with pytest.raises(
@@ -45,19 +43,9 @@ def test_custom_jinja_template_invalid_path(monkeypatch):
         parse_args(sys.argv[1:])
 
 
-def test_custom_jinja_template_valid_path(monkeypatch):
+def test_custom_jinja_template_valid_path(mock_sglang_cli):
     """Test that valid absolute path is stored correctly."""
-    monkeypatch.setattr(
-        sys,
-        "argv",
-        [
-            "dynamo.sglang",
-            "--model-path",
-            "Qwen/Qwen3-0.6B",
-            "--custom-jinja-template",
-            JINJA_TEMPLATE_PATH,
-        ],
-    )
+    mock_sglang_cli(model="Qwen/Qwen3-0.6B", custom_jinja_template=JINJA_TEMPLATE_PATH)
 
     config = parse_args(sys.argv[1:])
 
@@ -67,23 +55,13 @@ def test_custom_jinja_template_valid_path(monkeypatch):
     )
 
 
-def test_custom_jinja_template_env_var_expansion(monkeypatch):
+def test_custom_jinja_template_env_var_expansion(monkeypatch, mock_sglang_cli):
     """Test that environment variables in paths are expanded by Python code."""
     jinja_dir = str(TEST_DIR / "serve" / "fixtures")
     monkeypatch.setenv("JINJA_DIR", jinja_dir)
 
     cli_path = "$JINJA_DIR/custom_template.jinja"
-    monkeypatch.setattr(
-        sys,
-        "argv",
-        [
-            "dynamo.sglang",
-            "--model-path",
-            "Qwen/Qwen3-0.6B",
-            "--custom-jinja-template",
-            cli_path,
-        ],
-    )
+    mock_sglang_cli(model="Qwen/Qwen3-0.6B", custom_jinja_template=cli_path)
 
     config = parse_args(sys.argv[1:])
 

tests/unit/test_trtllm_unit.py

@@ -4,12 +4,12 @@
 """Unit tests for TRTLLM backend components."""
 
 import re
-import sys
 from pathlib import Path
 
 import pytest
 
 from dynamo.trtllm.utils.trtllm_utils import cmd_line_args
+from tests.unit.conftest import make_cli_args_fixture
 
 # Get path relative to this test file
 TEST_DIR = Path(__file__).parent.parent
@@ -23,42 +23,28 @@ pytestmark = [
 ]
 
 
-def test_custom_jinja_template_invalid_path(monkeypatch):
+# Create TRTLLM-specific CLI args fixture
+# This will use monkeypatch to write to argv
+mock_trtllm_cli = make_cli_args_fixture("dynamo.trtllm")
+
+
+def test_custom_jinja_template_invalid_path(mock_trtllm_cli):
     """Test that invalid file path raises FileNotFoundError."""
     invalid_path = "/nonexistent/path/to/template.jinja"
-    monkeypatch.setattr(
-        sys,
-        "argv",
-        [
-            "dynamo.trtllm",
-            "--model-path",
-            "Qwen/Qwen3-0.6B",
-            "--custom-jinja-template",
-            invalid_path,
-        ],
+    mock_trtllm_cli(
+        "--model", "Qwen/Qwen3-0.6B", "--custom-jinja-template", invalid_path
     )
 
     with pytest.raises(
         FileNotFoundError,
         match=re.escape(f"Custom Jinja template file not found: {invalid_path}"),
     ):
-        cmd_line_args()
+        cmd_line_args()  # This will read in from argv
 
 
-def test_custom_jinja_template_valid_path(monkeypatch):
+def test_custom_jinja_template_valid_path(mock_trtllm_cli):
     """Test that valid absolute path is stored correctly."""
-    monkeypatch.setattr(
-        sys,
-        "argv",
-        [
-            "dynamo.trtllm",
-            "--model-path",
-            "Qwen/Qwen3-0.6B",
-            "--custom-jinja-template",
-            JINJA_TEMPLATE_PATH,
-        ],
-    )
-
+    mock_trtllm_cli(model="Qwen/Qwen3-0.6B", custom_jinja_template=JINJA_TEMPLATE_PATH)
     config = cmd_line_args()
 
     assert config.custom_jinja_template == JINJA_TEMPLATE_PATH, (
@@ -67,23 +53,13 @@ def test_custom_jinja_template_valid_path(monkeypatch):
     )
 
 
-def test_custom_jinja_template_env_var_expansion(monkeypatch):
+def test_custom_jinja_template_env_var_expansion(monkeypatch, mock_trtllm_cli):
     """Test that environment variables in paths are expanded by Python code."""
     jinja_dir = str(TEST_DIR / "serve" / "fixtures")
     monkeypatch.setenv("JINJA_DIR", jinja_dir)
 
     cli_path = "$JINJA_DIR/custom_template.jinja"
-    monkeypatch.setattr(
-        sys,
-        "argv",
-        [
-            "dynamo.trtllm",
-            "--model-path",
-            "Qwen/Qwen3-0.6B",
-            "--custom-jinja-template",
-            cli_path,
-        ],
-    )
+    mock_trtllm_cli(model="Qwen/Qwen3-0.6B", custom_jinja_template=cli_path)
 
     config = cmd_line_args()
 

tests/unit/test_vllm_unit.py

@@ -4,12 +4,12 @@
 """Unit tests for vLLM backend components."""
 
 import re
-import sys
 from pathlib import Path
 
 import pytest
 
 from dynamo.vllm.args import parse_args
+from tests.unit.conftest import make_cli_args_fixture
 
 # Get path relative to this test file
 TEST_DIR = Path(__file__).parent.parent
@@ -23,20 +23,16 @@ pytestmark = [
 ]
 
 
-def test_custom_jinja_template_invalid_path(monkeypatch):
+# Create vLLM-specific CLI args fixture
+# This will use monkeypatch to write to argv
+mock_vllm_cli = make_cli_args_fixture("dynamo.vllm")
+
+
+def test_custom_jinja_template_invalid_path(mock_vllm_cli):
     """Test that invalid file path raises FileNotFoundError."""
     invalid_path = "/nonexistent/path/to/template.jinja"
-    monkeypatch.setattr(
-        sys,
-        "argv",
-        [
-            "dynamo.vllm",
-            "--model",
-            "Qwen/Qwen3-0.6B",
-            "--custom-jinja-template",
-            invalid_path,
-        ],
-    )
+
+    mock_vllm_cli("--model", "Qwen/Qwen3-0.6B", "--custom-jinja-template", invalid_path)
 
     with pytest.raises(
         FileNotFoundError,
@@ -45,19 +41,9 @@ def test_custom_jinja_template_invalid_path(monkeypatch):
         parse_args()
 
 
-def test_custom_jinja_template_valid_path(monkeypatch):
+def test_custom_jinja_template_valid_path(mock_vllm_cli):
     """Test that valid absolute path is stored correctly."""
-    monkeypatch.setattr(
-        sys,
-        "argv",
-        [
-            "dynamo.vllm",
-            "--model",
-            "Qwen/Qwen3-0.6B",
-            "--custom-jinja-template",
-            JINJA_TEMPLATE_PATH,
-        ],
-    )
+    mock_vllm_cli(model="Qwen/Qwen3-0.6B", custom_jinja_template=JINJA_TEMPLATE_PATH)
 
     config = parse_args()
 
@@ -67,23 +53,13 @@ def test_custom_jinja_template_valid_path(monkeypatch):
     )
 
 
-def test_custom_jinja_template_env_var_expansion(monkeypatch):
+def test_custom_jinja_template_env_var_expansion(monkeypatch, mock_vllm_cli):
     """Test that environment variables in paths are expanded by Python code."""
     jinja_dir = str(TEST_DIR / "serve" / "fixtures")
     monkeypatch.setenv("JINJA_DIR", jinja_dir)
 
     cli_path = "$JINJA_DIR/custom_template.jinja"
-    monkeypatch.setattr(
-        sys,
-        "argv",
-        [
-            "dynamo.vllm",
-            "--model",
-            "Qwen/Qwen3-0.6B",
-            "--custom-jinja-template",
-            cli_path,
-        ],
-    )
+    mock_vllm_cli(model="Qwen/Qwen3-0.6B", custom_jinja_template=cli_path)
 
     config = parse_args()