Uv4

nox/virtualenv.py

@@ -69,12 +69,18 @@ def find_uv() -> tuple[bool, str]:
 
 
 def uv_version() -> version.Version:
-    ret = subprocess.run(
-        [UV, "version", "--output-format", "json"],
-        check=False,
-        text=True,
-        capture_output=True,
-    )
+    """Returns uv's version defaulting to 0.0 if uv is not available"""
+    try:
+        ret = subprocess.run(
+            [UV, "version", "--output-format", "json"],
+            check=False,
+            text=True,
+            capture_output=True,
+        )
+    except FileNotFoundError:
+        logger.info("uv binary not found.")
+        return version.Version("0.0")
+
     if ret.returncode == 0 and ret.stdout:
         return version.Version(json.loads(ret.stdout).get("version"))
     else:
@@ -92,10 +98,9 @@ def uv_install_python(python_version: str) -> bool:
 
 
 HAS_UV, UV = find_uv()
-if HAS_UV:
-    # supported since uv 0.3 but 0.4.16 is the first version that doesn't cause
-    # issues for nox with pypy/cpython confusion
-    UV_PYTHON_SUPPORT = uv_version() >= version.Version("0.4.16")
+# supported since uv 0.3 but 0.4.16 is the first version that doesn't cause
+# issues for nox with pypy/cpython confusion
+UV_PYTHON_SUPPORT = uv_version() >= version.Version("0.4.16")
 
 
 class InterpreterNotFound(OSError):

tests/test_virtualenv.py

@@ -633,7 +633,7 @@ def find_uv_bin():
         (1, '{"version": "9.9.9", "commit_info": null}', "0.0"),
     ],
 )
-def test_uv_version_error(monkeypatch, return_code, stdout, expected_result):
+def test_uv_version(monkeypatch, return_code, stdout, expected_result):
     def mock_run(*args, **kwargs):
         return subprocess.CompletedProcess(
             args=["uv", "version", "--output-format", "json"],
@@ -645,6 +645,14 @@ def mock_run(*args, **kwargs):
     assert nox.virtualenv.uv_version() == version.Version(expected_result)
 
 
+def test_uv_version_no_uv(monkeypatch):
+    def mock_exception(*args, **kwargs):
+        raise FileNotFoundError
+
+    monkeypatch.setattr(subprocess, "run", mock_exception)
+    assert nox.virtualenv.uv_version() == version.Version("0.0")
+
+
 @pytest.mark.parametrize(
     ["requested_python", "expected_result"],
     [