Fix path separator for generated YAML on Windows (fixes #68)

tests/test_yaml.py

@@ -6,7 +6,7 @@
 
 from tests.utils import read_yaml_test_data
 from valohai.internals.merge import python_to_yaml_merge_strategy
-from valohai.internals.yaml import parse_config_from_source
+from valohai.internals.yaml import parse_config_from_source, generate_step
 from valohai.yaml import config_to_yaml
 
 
@@ -41,3 +41,24 @@ def test_yaml_update_from_source(tmpdir, original_yaml, source_python, expected_
     with open(expected_yaml) as expected_yaml:
         new_yaml = config_to_yaml(new_config)
         assert new_yaml == expected_yaml.read()
+
+
+def test_posix_path_separator():
+    # Let's be sneaky and force the path separator to simulate Windows
+    original_separator = os.sep
+    os.sep = "\\"
+
+    try:
+        step = generate_step(
+            relative_source_path="subfolder\\foo\\bar\\train.py",
+            step="train",
+            image="python:3.8",
+            parameters={},
+            inputs={},
+        )
+
+        # We expect the path separator be POSIX now
+        assert any("subfolder/foo/bar/train.py" in command for command in step.command)
+    finally:
+        # Try/finally just to be safe about resetting the separator back
+        os.sep = original_separator

valohai/internals/yaml.py

@@ -146,6 +146,10 @@ def get_parameter_type_name(name: str, value: Any) -> str:
 
 
 def get_command(relative_source_path: str) -> List[str]:
+    # We need to generate a POSIX-compliant command, even if we are running this method in Windows
+    # The path separator must be forced to POSIX
+    relative_source_path = relative_source_path.replace(os.sep, "/")
+
     if is_notebook_path(relative_source_path):
         return get_notebook_command(relative_source_path)