Skip python test.

Author: trivialfis

python-package/xgboost/testing/__init__.py

@@ -93,6 +93,14 @@ def no_ipv6() -> PytestSkip:
     return {"condition": not has_ipv6(), "reason": "IPv6 is required to be enabled."}
 
 
+def no_unix() -> PytestSkip:
+    """PyTest skip mark for non-unix."""
+    return {
+        "condition": system() == "Windows",
+        "reason": "unix system is required to be enabled.",
+    }
+
+
 def no_ubjson() -> PytestSkip:
     return no_mod("ubjson")
 

tests/python/test_demos.py

@@ -103,6 +103,7 @@ def test_cross_validation_demo():
     subprocess.check_call(cmd)
 
 
+@pytest.mark.skipif(**tm.no_unix())
 def test_external_memory_demo():
     script = os.path.join(PYTHON_DEMO_DIR, 'external_memory.py')
     cmd = ['python', script]