Add comprehensive tests for plugin management and IPC functionality

- Introduced tests for the plugin catalogue installation and update flows in `test_plugin_catalogue_install.py`.
- Added unit tests for the GitHub Releases plugin client in `test_plugin_github_releases.py`.
- Implemented IPC tests for the plugin manager Unix socket protocol in `test_plugin_ipc.py`.
- Created lifecycle and installation tests for the plugin manager in `test_plugin_manager_lifecycle.py`.
- Added tests for plugin manifest parsing in `test_plugin_manifest.py`.
- Developed tests for plugin filesystem layout and state management in `test_plugin_storage.py`.

tests/test_plugin_github_releases.py

@@ -0,0 +1,174 @@
+"""Unit tests for GitHub Releases plugin client."""
+
+from __future__ import annotations
+
+import io
+import json
+from pathlib import Path
+from urllib.error import HTTPError
+from urllib.request import Request
+
+import pytest
+
+from repeater.plugins.github_releases import (
+    GitHubRateLimitError,
+    GitHubReleaseClient,
+    GitHubReleasesError,
+    PluginRelease,
+    ReleaseAsset,
+    normalize_version,
+    select_wheel_asset,
+)
+
+
+def _release(
+    tag: str,
+    *,
+    draft: bool = False,
+    prerelease: bool = False,
+    assets: list[dict] | None = None,
+):
+    return {
+        "tag_name": tag,
+        "name": tag,
+        "body": f"notes for {tag}",
+        "draft": draft,
+        "prerelease": prerelease,
+        "html_url": f"https://github.com/org/repo/releases/tag/{tag}",
+        "published_at": "2026-01-01T00:00:00Z",
+        "assets": assets
+        or [
+            {
+                "name": f"pkg-{tag.lstrip('v')}-py3-none-any.whl",
+                "browser_download_url": f"https://example.test/{tag}.whl",
+                "size": 12,
+                "content_type": "application/octet-stream",
+            }
+        ],
+    }
+
+
+class _FakeResp(io.BytesIO):
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        return False
+
+
+def test_normalize_version():
+    assert normalize_version("v1.2.3") == "1.2.3"
+    assert normalize_version("1.2.3") == "1.2.3"
+    assert normalize_version("V0.1.0") == "0.1.0"
+
+
+def test_stable_release_discovery_and_ordering():
+    payload = [
+        _release("v0.1.0"),
+        _release("v0.3.0"),
+        _release("v0.2.0", prerelease=True),
+        _release("v0.4.0", draft=True),
+    ]
+
+    def opener(request: Request, timeout: float = 30.0):
+        if "api.github.com" in request.full_url:
+            return _FakeResp(json.dumps(payload).encode())
+        raise AssertionError(request.full_url)
+
+    client = GitHubReleaseClient(opener=opener, cache_ttl=60)
+    releases = client.list_releases("openhop-dev/openhop-nomad-plugin")
+    assert [r.version for r in releases] == ["0.3.0", "0.1.0"]
+    latest = client.latest_stable("openhop-dev/openhop-nomad-plugin")
+    assert latest.version == "0.3.0"
+
+
+def test_wheel_asset_selection():
+    rel = PluginRelease(
+        tag="v1.0.0",
+        version="1.0.0",
+        name="1.0.0",
+        body="",
+        prerelease=False,
+        draft=False,
+        html_url="",
+        published_at="",
+        assets=(
+            ReleaseAsset("notes.txt", "https://x/notes.txt"),
+            ReleaseAsset("pkg-1.0.0-py3-none-any.whl", "https://x/pkg.whl"),
+        ),
+    )
+    assert select_wheel_asset(rel).name.endswith(".whl")
+
+    none = PluginRelease(
+        tag="v1",
+        version="1",
+        name="",
+        body="",
+        prerelease=False,
+        draft=False,
+        html_url="",
+        published_at="",
+        assets=(ReleaseAsset("x.zip", "https://x/x.zip"),),
+    )
+    with pytest.raises(GitHubReleasesError, match="no .whl"):
+        select_wheel_asset(none)
+
+    many = PluginRelease(
+        tag="v1",
+        version="1",
+        name="",
+        body="",
+        prerelease=False,
+        draft=False,
+        html_url="",
+        published_at="",
+        assets=(
+            ReleaseAsset("a.whl", "https://x/a.whl"),
+            ReleaseAsset("b.whl", "https://x/b.whl"),
+        ),
+    )
+    with pytest.raises(GitHubReleasesError, match="multiple"):
+        select_wheel_asset(many)
+
+
+def test_download_wheel(tmp_path: Path):
+    payload = [_release("v0.1.0")]
+
+    def opener(request: Request, timeout: float = 30.0):
+        if "api.github.com" in request.full_url:
+            return _FakeResp(json.dumps(payload).encode())
+        if request.full_url.endswith(".whl"):
+            return _FakeResp(b"wheel-bytes")
+        raise AssertionError(request.full_url)
+
+    client = GitHubReleaseClient(opener=opener)
+    release, path = client.download_latest_wheel("org/repo", tmp_path)
+    assert release.version == "0.1.0"
+    assert path.read_bytes() == b"wheel-bytes"
+    assert path.name.endswith(".whl")
+
+
+def test_rate_limit():
+    def opener(request: Request, timeout: float = 30.0):
+        headers = {"X-RateLimit-Remaining": "0"}
+        raise HTTPError(request.full_url, 403, "rate limit", hdrs=headers, fp=None)
+
+    client = GitHubReleaseClient(opener=opener)
+    with pytest.raises(GitHubRateLimitError):
+        client.list_releases("org/repo")
+
+
+def test_cache_behaviour():
+    calls = {"n": 0}
+    payload = [_release("v1.0.0")]
+
+    def opener(request: Request, timeout: float = 30.0):
+        calls["n"] += 1
+        return _FakeResp(json.dumps(payload).encode())
+
+    client = GitHubReleaseClient(opener=opener, cache_ttl=60)
+    client.list_releases("org/repo")
+    client.list_releases("org/repo")
+    assert calls["n"] == 1
+    client.list_releases("org/repo", force_refresh=True)
+    assert calls["n"] == 2