test: skip clone when client is not available

Author: paugier

test/functional/test_download_clone.py

@@ -1,12 +1,25 @@
+import shutil
+
 import pytest
 
 from install_locked_env.downloaders import download_via_clone
 
 from .util import get_url_info_env
 
 
+has_hg = bool(shutil.which("hg"))
+has_git = bool(shutil.which("git"))
+skipif = pytest.mark.skipif
+
+
 @pytest.mark.slow
-@pytest.mark.parametrize("platform", ["github", "heptapod"])
+@pytest.mark.parametrize(
+    "platform",
+    [
+        pytest.param("github", marks=skipif(not has_git, reason="Needs Git")),
+        pytest.param("heptapod", marks=skipif(not has_hg, reason="Needs Mercurial")),
+    ],
+)
 def test_download_via_clone(tmp_path, platform):
     """test download via archives"""
     url_info = get_url_info_env(platform, "root")