1 files changed, 158 insertions, 0 deletions
diff --git a/packages/meshbay-hub/tests/test_resume_position.py b/packages/meshbay-hub/tests/test_resume_position.py
new file mode 100644
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+++ b/packages/meshbay-hub/tests/test_resume_position.py
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+"""
+"Resume where you left off" belongs to an account, not to a machine.
+
+The position was stored as `mb:pos:<file>` in localStorage — per *device*. Sign
+in with a second account on the same computer and the player offered to resume a
+film that account had never opened. Wrong on its own terms, and a small
+disclosure of what the other person watches: the offer only appears for files
+someone has actually been through.
+
+The functions are lifted out of `app.js` and run for real, rather than having
+their source inspected, because the thing worth holding is the behaviour of two
+accounts sharing one storage — which no assertion about the source text says.
+"""
+
+import json
+import re
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+STATIC = Path(__file__).resolve().parents[1] / "src" / "meshbay_hub" / "static"
+APP = STATIC / "app.js"
+
+pytestmark = pytest.mark.skipif(
+    shutil.which("node") is None or not APP.exists(),
+    reason="node or the SPA sources are not available")
+
+WANTED = ("resumeKey", "readResumePosition", "writeResumePosition",
+          "purgeUnscopedResumePositions")
+
+
+def _extract() -> str:
+    """The real source of the functions under test, and nothing else.
+
+    `app.js` imports preact and cannot be loaded outside a browser, so the
+    declarations are sliced out by brace matching. A rename breaks this loudly,
+    which is the intent — a silently skipped test is worse than a failing one.
+    """
+    source = APP.read_text(encoding="utf-8")
+    out = [
+        f"const RESUME_MIN_S = {_const(source, 'RESUME_MIN_S')};",
+        f"const RESUME_MAX_FRACTION = {_const(source, 'RESUME_MAX_FRACTION')};",
+    ]
+    for name in WANTED:
+        start = source.index(f"function {name}(")
+        depth, i = 0, source.index("{", start)
+        while True:
+            if source[i] == "{":
+                depth += 1
+            elif source[i] == "}":
+                depth -= 1
+                if depth == 0:
+                    break
+            i += 1
+        out.append(source[start:i + 1])
+    return "\n".join(out)
+
+
+def _const(source: str, name: str) -> str:
+    match = re.search(rf"^const {name} = ([^;]+);", source, re.M)
+    assert match, f"{name} is gone or was renamed"
+    return match.group(1)
+
+
+def _run(body: str, tmp_path: Path):
+    script = tmp_path / "case.mjs"
+    script.write_text(
+        "const store = new Map();\n"
+        "globalThis.localStorage = {\n"
+        "  get length() { return store.size; },\n"
+        "  key: i => Array.from(store.keys())[i] ?? null,\n"
+        "  getItem: k => (store.has(k) ? store.get(k) : null),\n"
+        "  setItem: (k, v) => store.set(k, String(v)),\n"
+        "  removeItem: k => store.delete(k),\n"
+        "};\n"
+        # Whoever is signed in, swapped by the cases below.
+        "let AUTH = null;\n"
+        "function loadAuth() { return AUTH; }\n"
+        f"{_extract()}\n"
+        "const out = [];\n"
+        "const say = (...a) => out.push(...a);\n"
+        "const keys = () => Array.from(store.keys()).sort();\n"
+        f"{body}\n"
+        "console.log(JSON.stringify(out));\n",
+        encoding="utf-8")
+    proc = subprocess.run(["node", str(script)], capture_output=True, text=True)
+    assert proc.returncode == 0, proc.stderr
+    return json.loads(proc.stdout)
+
+
+# ── The bug ─────────────────────────────────────────────────────────────────
+
+def test_a_second_account_is_not_offered_the_firsts_position(tmp_path):
+    """The report: a brand-new account was offered a resume point."""
+    assert _run("""
+AUTH = { userId: 'alice' };
+writeResumePosition('film1', 600, 7200);
+say(readResumePosition('film1'));
+
+AUTH = { userId: 'bob' };
+say(readResumePosition('film1'));
+""", tmp_path) == [600, 0]
+
+
+def test_each_account_keeps_its_own_place_in_the_same_film(tmp_path):
+    """Two people watching one film on one machine is the ordinary case, and
+    neither should move the other's bookmark."""
+    assert _run("""
+AUTH = { userId: 'alice' }; writeResumePosition('film1', 600, 7200);
+AUTH = { userId: 'bob' };   writeResumePosition('film1', 1800, 7200);
+AUTH = { userId: 'alice' }; say(readResumePosition('film1'));
+AUTH = { userId: 'bob' };   say(readResumePosition('film1'));
+""", tmp_path) == [600, 1800]
+
+
+def test_nothing_is_written_when_nobody_is_signed_in(tmp_path):
+    assert _run("""
+AUTH = null;
+writeResumePosition('film1', 600, 7200);
+say(keys().length, readResumePosition('film1'));
+""", tmp_path) == [0, 0]
+
+
+def test_positions_written_before_the_fix_are_dropped(tmp_path):
+    """
+    They cannot be re-keyed: there is no record of whose they were, and guessing
+    hands them to whoever signs in next, which is the bug itself.
+    """
+    assert _run("""
+localStorage.setItem('mb:pos:film1', '600');       // the old shape
+localStorage.setItem('mb:pos:alice:film2', '900'); // the new one
+localStorage.setItem('mb_auth', '{}');             // nothing to do with this
+purgeUnscopedResumePositions();
+say(...keys());
+""", tmp_path) == ["mb:pos:alice:film2", "mb_auth"]
+
+
+# ── What must still hold ────────────────────────────────────────────────────
+
+def test_a_glance_at_the_opening_is_not_a_bookmark(tmp_path):
+    assert _run("""
+AUTH = { userId: 'alice' };
+writeResumePosition('film1', 12, 7200);
+say(readResumePosition('film1'));
+""", tmp_path) == [0]
+
+
+def test_a_film_watched_to_the_end_stops_offering_to_resume(tmp_path):
+    """And the earlier bookmark goes with it, rather than sitting there
+    offering the last thirty seconds forever."""
+    assert _run("""
+AUTH = { userId: 'alice' };
+writeResumePosition('film1', 3600, 7200);
+writeResumePosition('film1', 7150, 7200);
+say(readResumePosition('film1'), keys().length);
+""", tmp_path) == [0, 0]