[#253]: Test SQLite cache requests document loader

Author: anatoly-scherbakov

tests/test_sqlite_cache_requests_document_loader.py

@@ -0,0 +1,117 @@
+"""Tests for SqliteCacheRequestsDocumentLoader and HTTP cache behavior."""
+
+import json
+import threading
+from http.server import BaseHTTPRequestHandler, HTTPServer
+from pathlib import Path
+
+import pytest
+
+from pyld import (
+    DocumentLoader,
+    RequestsDocumentLoader,
+    SqliteCacheRequestsDocumentLoader,
+)
+
+requests_cache = pytest.importorskip('requests_cache')
+CachedSession = requests_cache.CachedSession
+
+
+class _ContextHandler(BaseHTTPRequestHandler):
+    request_count = 0
+
+    def do_GET(self):
+        type(self).request_count += 1
+        body = json.dumps({
+            '@context': {'name': 'http://example.org/name'},
+        }).encode()
+        self.send_response(200)
+        self.send_header('Content-Type', 'application/ld+json')
+        self.send_header('Cache-Control', 'max-age=3600')
+        self.end_headers()
+        self.wfile.write(body)
+
+    def log_message(self, format, *args):
+        pass
+
+
+@pytest.fixture
+def context_url():
+    """Local HTTP server returning JSON-LD with Cache-Control: max-age=3600."""
+    _ContextHandler.request_count = 0
+    server = HTTPServer(('127.0.0.1', 0), _ContextHandler)
+    thread = threading.Thread(target=server.serve_forever, daemon=True)
+    thread.start()
+    port = server.server_address[1]
+    url = f'http://127.0.0.1:{port}/context.jsonld'
+    yield url
+    server.shutdown()
+
+
+def test_requests_document_loader_accepts_custom_session():
+    """RequestsDocumentLoader accepts a CachedSession via session=."""
+    loader = RequestsDocumentLoader(
+        session=CachedSession(backend='memory', cache_control=True))
+    assert isinstance(loader, DocumentLoader)
+    assert callable(loader)
+    loader.session.close()
+
+
+def test_sqlite_cache_requests_document_loader_is_document_loader():
+    """Sqlite loader is a DocumentLoader composing RequestsDocumentLoader."""
+    loader = SqliteCacheRequestsDocumentLoader()
+    assert isinstance(loader, DocumentLoader)
+    assert isinstance(loader._loader, RequestsDocumentLoader)
+    assert callable(loader)
+    loader.session.close()
+
+
+def test_sqlite_cache_requests_document_loader_rejects_relative_sqlite_file_path():
+    """Relative sqlite_file_path is rejected."""
+    with pytest.raises(ValueError, match='absolute path'):
+        SqliteCacheRequestsDocumentLoader(
+            sqlite_file_path=Path('relative.sqlite'))
+
+
+def test_http_cache_headers_serve_from_cache_with_cache_control(context_url):
+    """With cache_control=True, Cache-Control max-age avoids a second HTTP hit."""
+    loader = RequestsDocumentLoader(
+        session=CachedSession(
+            'test_memory_cache_control',
+            backend='memory',
+            cache_control=True,
+        ))
+    loader(context_url)
+    loader(context_url)
+    assert _ContextHandler.request_count == 1
+    loader.session.close()
+
+
+def test_http_cache_headers_without_cache_control_hits_server_twice(context_url):
+    """With cache_control=False, response Cache-Control headers are ignored."""
+    loader = RequestsDocumentLoader(
+        session=CachedSession(
+            'test_memory_no_cache_control',
+            backend='memory',
+            cache_control=False,
+            expire_after=0,
+        ))
+    loader(context_url)
+    loader(context_url)
+    assert _ContextHandler.request_count == 2
+    loader.session.close()
+
+
+def test_sqlite_cache_requests_document_loader_persists(context_url, tmp_path):
+    """Second loader instance reuses the on-disk SQLite cache."""
+    cache_path = tmp_path / 'contexts.sqlite'
+    loader = SqliteCacheRequestsDocumentLoader(sqlite_file_path=cache_path)
+    loader(context_url)
+    assert _ContextHandler.request_count == 1
+    loader.session.close()
+
+    _ContextHandler.request_count = 0
+    loader = SqliteCacheRequestsDocumentLoader(sqlite_file_path=cache_path)
+    loader(context_url)
+    assert _ContextHandler.request_count == 0
+    loader.session.close()