test: wait for Linux service environment readiness

tests/test_gcp_leoclean_service_environment.py

@@ -2,6 +2,7 @@ import json
 import os
 import subprocess
 import sys
+import time
 from collections.abc import Mapping
 from pathlib import Path
 
@@ -14,6 +15,27 @@ def environment_block(environment: Mapping[str, str]) -> bytes:
     return b"\0".join(f"{key}={value}".encode() for key, value in environment.items()) + b"\0"
 
 
+def wait_for_process_environment(
+    process: subprocess.Popen[bytes],
+    expected: Mapping[str, str],
+    *,
+    timeout_seconds: float = 5.0,
+) -> None:
+    deadline = time.monotonic() + timeout_seconds
+    while time.monotonic() < deadline:
+        if process.poll() is not None:
+            pytest.fail("environment fixture process exited before becoming readable")
+        try:
+            observed = verifier.parse_environment(Path(f"/proc/{process.pid}/environ").read_bytes())
+        except (OSError, verifier.VerificationError):
+            time.sleep(0.01)
+            continue
+        if observed == expected:
+            return
+        time.sleep(0.01)
+    pytest.fail("environment fixture process did not become readable")
+
+
 def test_all_expected_fields_pass_and_receipt_contains_no_values() -> None:
     environment = verifier.expected_environment()
     environment.update({"HOME": "/home/teleo", "LANG": "C.UTF-8"})
@@ -234,6 +256,7 @@ def test_cli_reads_real_process_environment_and_detects_effective_conflict(
         stderr=subprocess.DEVNULL,
     )
     try:
+        wait_for_process_environment(good_process, expected)
         assert verifier.main(["--pid", str(good_process.pid)]) == 0
         good_output = capsys.readouterr()
         assert good_output.err == ""
@@ -253,6 +276,7 @@ def test_cli_reads_real_process_environment_and_detects_effective_conflict(
         stderr=subprocess.DEVNULL,
     )
     try:
+        wait_for_process_environment(bad_process, conflicting)
         assert verifier.main(["--pid", str(bad_process.pid)]) == 1
         bad_output = capsys.readouterr()
         receipt = json.loads(bad_output.out)