install report: added experimental status warning

Author: sbidoul

src/pip/_internal/commands/install.py

@@ -371,6 +371,12 @@ def run(self, options: Values, args: List[str]) -> int:
             )
 
             if options.json_report_file:
+                logger.warning(
+                    "--report is currently an experimental option. "
+                    "The output format may change in a future release "
+                    "without prior warning."
+                )
+
                 report = InstallationReport(requirement_set.requirements_to_install)
                 if options.json_report_file == "-":
                     print_json(data=report.to_dict())

tests/functional/test_install_report.py

@@ -26,6 +26,7 @@ def test_install_report_basic(
         str(shared_data.root / "packages/"),
         "--report",
         str(report_path),
+        allow_stderr_warning=True,
     )
     report = json.loads(report_path.read_text())
     assert "install" in report
@@ -58,6 +59,7 @@ def test_install_report_dep(
         str(shared_data.root / "packages/"),
         "--report",
         str(report_path),
+        allow_stderr_warning=True,
     )
     report = json.loads(report_path.read_text())
     assert len(report["install"]) == 2
@@ -76,6 +78,7 @@ def test_install_report_index(script: PipTestEnvironment, tmp_path: Path) -> Non
         "Paste[openid]==1.7.5.1",
         "--report",
         str(report_path),
+        allow_stderr_warning=True,
     )
     report = json.loads(report_path.read_text())
     assert len(report["install"]) == 2
@@ -111,6 +114,7 @@ def test_install_report_vcs_and_wheel_cache(
         str(cache_dir),
         "--report",
         str(report_path),
+        allow_stderr_warning=True,
     )
     report = json.loads(report_path.read_text())
     assert len(report["install"]) == 1
@@ -138,6 +142,7 @@ def test_install_report_vcs_and_wheel_cache(
         str(cache_dir),
         "--report",
         str(report_path),
+        allow_stderr_warning=True,
     )
     assert "Using cached pip_test_package" in result.stdout
     report = json.loads(report_path.read_text())
@@ -171,6 +176,7 @@ def test_install_report_vcs_editable(
         "#egg=pip-test-package",
         "--report",
         str(report_path),
+        allow_stderr_warning=True,
     )
     report = json.loads(report_path.read_text())
     assert len(report["install"]) == 1
@@ -197,8 +203,12 @@ def test_install_report_to_stdout(
         str(shared_data.root / "packages/"),
         "--report",
         "-",
+        allow_stderr_warning=True,
+    )
+    assert result.stderr == (
+        "WARNING: --report is currently an experimental option. "
+        "The output format may change in a future release without prior warning.\n"
     )
-    assert not result.stderr
     report = json.loads(result.stdout)
     assert "install" in report
     assert len(report["install"]) == 1