fix: prepare coordinated candidates in one consumer graph

Author: Sunrisepeak

tests/autoupdate/ci.py

@@ -300,8 +300,24 @@ def archive_of(record):
     print(f"Candidate matrix: {len(jobs)} real build/run jobs.")
 
 
+def replace_candidate(text: str, identity: str, version: str) -> str:
+    namespace, name = identity.split(":", 1)
+    text, replacements = re.subn(
+        rf'(?m)^(\s*(?:{re.escape(name)}|"{re.escape(namespace)}\.{re.escape(name)}")\s*=\s*(?:\{{\s*version\s*=\s*)?")[^"]+(".*)$',
+        lambda m: m[1] + version + m[2], text)
+    if not replacements:
+        # A platform the member selects (mcpp SPEC-013).
+        text, replacements = re.subn(
+            rf'(?m)^(\s*platform\s*=\s*"(?:{re.escape(namespace)}\.)?{re.escape(name)}@)[^"]+(".*)$',
+            lambda m: m[1] + version + m[2], text)
+    if not replacements:
+        raise RuntimeError("candidate dependency was not replaced: " + identity)
+    return text
+
+
 def prepare(plan: Path, identity: str, output: Path, home: Path | None = None):
-    record = next(r for r in json.loads(plan.read_text(encoding="utf-8"))["packages"] if r["id"] == identity)
+    candidates = json.loads(plan.read_text(encoding="utf-8"))["packages"]
+    record = next(r for r in candidates if r["id"] == identity)
     namespace, name = identity.split(":", 1)
     version = record["candidate"]
     member = direct_member(identity)
@@ -311,16 +327,13 @@ def prepare(plan: Path, identity: str, output: Path, home: Path | None = None):
         shutil.copytree(source, output, dirs_exist_ok=True,
                         ignore=shutil.ignore_patterns("target", ".mcpp", "mcpp.lock"))
         text = (output / "mcpp.toml").read_text(encoding="utf-8")
-        text, replacements = re.subn(
-            rf'(?m)^(\s*(?:{re.escape(name)}|"{re.escape(namespace)}\.{re.escape(name)}")\s*=\s*(?:\{{\s*version\s*=\s*)?")[^"]+(".*)$',
-            lambda m: m[1] + version + m[2], text)
-        if not replacements:
-            # A platform the member selects (mcpp SPEC-013): `platform = "<name>@<version>"`.
-            text, replacements = re.subn(
-                rf'(?m)^(\s*platform\s*=\s*"(?:{re.escape(namespace)}\.)?{re.escape(name)}@)[^"]+(".*)$',
-                lambda m: m[1] + version + m[2], text)
-        if not replacements:
-            raise RuntimeError("candidate dependency was not replaced")
+        # One change plan may advance an ABI group together. Replacing only
+        # this row creates a mixture the resolver correctly rejects. Apply
+        # exactly the planned candidates mapped to this same real consumer;
+        # unplanned dependencies retain the fixture's constraints.
+        for candidate in candidates:
+            if direct_member(candidate["id"]) == member:
+                text = replace_candidate(text, candidate["id"], candidate["candidate"])
         # Standalone consumer: no inherited workspace or stale relative index redirects.
         text = re.sub(r'(?ms)^\[indices(?:\.[^\]]+)?\]\s*\n.*?(?=^\[|\Z)', '', text)
     else:

tests/autoupdate/test_ci.py

@@ -25,6 +25,43 @@ def descriptor(name):
 
 
 class BaselineTests(unittest.TestCase):
+    def test_one_consumer_uses_all_and_only_its_planned_candidates(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            source = root / "tests/examples/kernel"
+            source.mkdir(parents=True)
+            (source / "mcpp.toml").write_text(
+                '[package]\nname="kernel"\nversion="0.1.0"\n'
+                '[dependencies.mcpplibs]\nabi="0.23.0"\n'
+                '[target.linux.dependencies.mcpplibs]\nbackend="0.24.2"\n'
+                '[build-dependencies.compat]\nhelper="1.0.0"\n')
+            other = root / "tests/examples/other"
+            other.mkdir()
+            (other / "mcpp.toml").write_text(
+                '[package]\nname="other"\nversion="0.1.0"\n'
+                '[dependencies.compat]\nunrelated="1.0.0"\n')
+            plan = root / "plan.json"
+            candidates = [{"id": "mcpplibs:abi", "candidate": "0.24.0"},
+                          {"id": "mcpplibs:backend", "candidate": "0.25.0"},
+                          {"id": "compat:unrelated", "candidate": "2.0.0"}]
+            with patch.object(ci, "ROOT", root):
+                for identity in ("mcpplibs:abi", "mcpplibs:backend"):
+                    plan.write_text(json.dumps({"packages": candidates}))
+                    dest = root / identity.split(":")[1]
+                    ci.prepare(plan, identity, dest)
+                    manifest = tomllib.loads((dest / "mcpp.toml").read_text())
+                    self.assertEqual(manifest["dependencies"]["mcpplibs"]["abi"], "0.24.0")
+                    self.assertEqual(manifest["target"]["linux"]["dependencies"]["mcpplibs"]["backend"], "0.25.0")
+                    self.assertEqual(manifest["build-dependencies"]["compat"]["helper"], "1.0.0")
+                    self.assertNotIn("unrelated", manifest.get("dependencies", {}).get("compat", {}))
+                # No implicit companion upgrade when it is absent from the plan.
+                plan.write_text(json.dumps({"packages": candidates[:1]}))
+                dest = root / "single"
+                ci.prepare(plan, "mcpplibs:abi", dest)
+                manifest = tomllib.loads((dest / "mcpp.toml").read_text())
+                self.assertEqual(manifest["dependencies"]["mcpplibs"]["abi"], "0.24.0")
+                self.assertEqual(manifest["target"]["linux"]["dependencies"]["mcpplibs"]["backend"], "0.24.2")
+
     def test_commit_snapshot_is_manual_but_historical_bytes_are_still_guarded(self):
         with tempfile.TemporaryDirectory() as directory:
             root = Path(directory)