Add test

src/python/pants/engine/internals/scheduler_integration_test.py

@@ -1,8 +1,11 @@
 # Copyright 2015 Pants project contributors (see CONTRIBUTORS.md).
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
+import re
 from pathlib import Path
+from textwrap import dedent
 
+from pants.base.build_environment import get_buildroot
 from pants.testutil.pants_run_integration_test import PantsRunIntegrationTest, ensure_daemon
 from pants.util.contextutil import temporary_dir
 
@@ -34,3 +37,49 @@ def test_graceful_termination(self):
             pants_result.stdout_data, "examples/src/python/example/hello/greet:greet\n",
         )
         self.assertEqual(pants_result.returncode, 42)
+
+    def prepare_concurrency_slot_sources(self, tmpdir: str) -> None:
+        src_root = Path(tmpdir, "src", "python", "project")
+        src_root.mkdir(parents=True)
+
+        (src_root / "fake_test.py").write_text(
+            dedent(
+                """\
+            import os
+
+            def test_fail_printing_slot_env_var():
+                slot = os.getenv("SLOT")
+                print(f"Value of slot is {slot}")
+                #Deliberately fail the test so the SLOT output gets printed
+                assert 1 == 2
+            """
+            )
+        )
+
+        (src_root / "BUILD").write_text(
+            dedent(
+                """\
+                python_tests(
+                    name="fake",
+                    sources=["fake_test.py"],
+                    dependencies=[],
+                )
+                """
+            )
+        )
+
+    def test_concurrency_slot_variable(self) -> None:
+        build_root = get_buildroot()
+        with temporary_dir(root_dir=build_root) as tmpdir:
+            tmpdir_relative = Path(tmpdir).relative_to(build_root)
+            self.prepare_concurrency_slot_sources(tmpdir)
+            result = self.run_pants(
+                [
+                    "--no-dynamic-ui",
+                    "--process-execution-slot-environment-variable=SLOT",
+                    "test",
+                    f"{tmpdir_relative}/src/python/project:fake",
+                ]
+            )
+
+            assert re.search(r"Value of slot is \d+", result.stderr_data)