testing: import virtualenv lazily

Fixes https://github.com/iterative/dvc/issues/10118

dvc/testing/benchmarks/cli/commands/test_fetch.py

@@ -0,0 +1,3 @@
+def test_fetch(bench_dvc, tmp_dir, dvc, make_dataset, remote):
+    make_dataset(cache=False, dvcfile=True, files=False, remote=True)
+    bench_dvc("fetch")

dvc/testing/benchmarks/cli/commands/test_pull.py

@@ -1,3 +0,0 @@
-def test_pull(bench_dvc, tmp_dir, dvc, make_dataset, remote):
-    make_dataset(cache=False, dvcfile=True, files=False, remote=True)
-    bench_dvc("pull")

dvc/testing/benchmarks/cli/stories/use_cases/test_sharing.py

@@ -11,7 +11,8 @@ def test_sharing(bench_dvc, tmp_dir, dvc, dataset, remote):
     shutil.rmtree(dataset)
     shutil.rmtree(tmp_dir / ".dvc" / "cache")
 
-    bench_dvc("pull")
-    bench_dvc("pull", name="noop")
+    bench_dvc("fetch")
+    bench_dvc("fetch", name="noop")
 
+    bench_dvc("checkout")
     bench_dvc("checkout", name="noop")

dvc/testing/benchmarks/fixtures.py

@@ -5,7 +5,6 @@ from subprocess import check_output
 from typing import Dict, Optional
 
 import pytest
-import virtualenv
 from dulwich.porcelain import clone
 from funcy import first
 from packaging import version
@@ -24,6 +23,8 @@ class VirtualEnv:
         self.bin = self.path / ("Scripts" if os.name == "nt" else "bin")
 
     def create(self) -> None:
+        import virtualenv
+
         virtualenv.cli_run([os.fspath(self.path)])
 
     def run(self, cmd: str, *args: str, env: Optional[Dict[str, str]] = None) -> None: