Add --list-dependencies options

src/tox/session/cmd/run/common.py

@@ -163,6 +163,19 @@ def __call__(
             help="skip package installation for this run",
             action="store_true",
         )
+        list_deps = parser.add_mutually_exclusive_group()
+        list_deps.add_argument(
+            "--list-dependencies",
+            action="store_true",
+            default="auto",
+            help="list the dependencies installed during environment setup",
+        )
+        list_deps.add_argument(
+            "--no-list-dependencies",
+            action="store_false",
+            dest="list_dependencies",
+            help="never list the dependencies installed during environment setup",
+        )
 
 
 def report(start: float, runs: list[ToxEnvRunResult], is_colored: bool, verbosity: int) -> int:

src/tox/tox_env/python/api.py

@@ -227,12 +227,14 @@ def prepend_env_var_path(self) -> list[Path]:
     def _done_with_setup(self) -> None:
         """called when setup is done"""
         super()._done_with_setup()
-        running_in_ci = is_ci()
-        if self.journal or running_in_ci:
+        list_deps = self.options.list_dependencies
+        if list_deps == "auto":
+            list_deps = is_ci()
+        if self.journal or list_deps:
             outcome = self.installer.installed()
             if self.journal:
                 self.journal["installed_packages"] = outcome
-            if running_in_ci:
+            if list_deps:
                 logging.warning(",".join(outcome))
 
     def python_cache(self) -> dict[str, Any]:

tests/tox_env/python/test_python_api.py

@@ -224,3 +224,19 @@ def test_list_installed_deps(in_ci: bool, tox_project: ToxProjectCreator, mocker
         assert "pip==" in result.out
     else:
         assert "pip==" not in result.out
+
+
+@pytest.mark.parametrize("list_deps", ["--list-dependencies", "--no-list-dependencies"])
+@pytest.mark.parametrize("in_ci", [True, False])
+def test_cli_list_installed_deps(
+    list_deps: str,
+    in_ci: bool,
+    tox_project: ToxProjectCreator,
+    mocker: MockerFixture,
+) -> None:
+    mocker.patch("tox.tox_env.python.api.is_ci", return_value=in_ci)
+    result = tox_project({"tox.ini": "[testenv]\nskip_install = true"}).run(list_deps, "r", "-e", "py")
+    if list_deps == "--list-dependencies":
+        assert "pip==" in result.out
+    else:
+        assert "pip==" not in result.out