Harden split background promotion preflight

backend/tests/test_sprint159_split_promotion_workflow.py

@@ -1,11 +1,32 @@
 from __future__ import annotations
 
+import json
+import os
+import shlex
+import subprocess
 from pathlib import Path
 
 
 ROOT = Path(__file__).resolve().parents[2]
 
 
+def _bash_path(path: Path) -> str:
+    raw_path = str(path)
+    if os.name != "nt":
+        return raw_path
+
+    result = subprocess.run(
+        ["bash", "-lc", f"wslpath -a {shlex.quote(raw_path)}"],
+        capture_output=True,
+        text=True,
+        timeout=10,
+        check=False,
+    )
+    if result.returncode == 0 and result.stdout.strip():
+        return result.stdout.strip()
+    return raw_path
+
+
 def test_split_background_promotion_workflow_runs_split_then_split_aware_report() -> None:
     script_path = ROOT / "scripts" / "run_split_background_promotion_workflow.sh"
     assert script_path.exists()
@@ -35,6 +56,54 @@ def test_split_background_promotion_workflow_has_safe_preflight_mode() -> None:
     assert "Split-background promotion preflight passed" in source
 
 
+def test_split_background_preflight_derives_missing_background_categories(tmp_path: Path) -> None:
+    positive_portfolio = tmp_path / "positive.json"
+    positive_portfolio.write_text('{"items":[]}', encoding="utf-8")
+    manifest = tmp_path / "operator_samples_manifest.json"
+    manifest.write_text(
+        json.dumps(
+            {
+                "samples": [
+                    {
+                        "sample_slug": "postel_bos",
+                        "sample_role": "background_candidate",
+                        "reference_feature_count": 0,
+                    },
+                    {
+                        "sample_slug": "kasterlee_bos",
+                        "sample_role": "background_candidate",
+                        "reference_feature_count": 7,
+                    },
+                ]
+            }
+        ),
+        encoding="utf-8",
+    )
+
+    api_root = tmp_path / "api-root"
+    projects_endpoint = api_root / "api" / "v1" / "projects"
+    projects_endpoint.parent.mkdir(parents=True)
+    projects_endpoint.write_text('{"data":{"items":[]}}', encoding="utf-8")
+
+    command = (
+        f"PROMOTION_POSITIVE_PORTFOLIO_PATH={shlex.quote(_bash_path(positive_portfolio))} "
+        f"OPERATOR_SAMPLE_MANIFEST_PATH={shlex.quote(_bash_path(manifest))} "
+        f"bash scripts/run_split_background_promotion_workflow.sh --preflight-only "
+        f"{shlex.quote(f'file://{_bash_path(api_root)}')}"
+    )
+    result = subprocess.run(
+        ["bash", "-lc", command],
+        cwd=ROOT,
+        capture_output=True,
+        text=True,
+        timeout=30,
+        check=False,
+    )
+
+    assert result.returncode == 0, result.stderr
+    assert "Split-background promotion preflight passed" in result.stdout
+
+
 def test_readiness_checks_split_background_promotion_workflow_syntax() -> None:
     readiness = (ROOT / "scripts" / "run_readiness_check.sh").read_text(encoding="utf-8")