add httpxyz fallback for async HTTP

.github/workflows/tests.yaml

@@ -335,28 +335,77 @@ jobs:
       - run: pip install tox
       - run: tox -e deptry
   async-niquests:
-    # Test that async code works with niquests when httpx is not installed
+    # Test that async code works with niquests when httpx/httpxyz are not installed
     name: async (niquests fallback)
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v5
         with:
           python-version: "3.12"
-      - name: Install dependencies without httpx
+      - name: Install dependencies without httpx/httpxyz
         run: |
           pip install --editable .[test]
-          pip uninstall -y httpx
+          pip uninstall -y httpx httpxyz
       - name: Verify niquests is used
         run: |
           python -c "
           from caldav.async_davclient import _USE_HTTPX, _USE_NIQUESTS
-          assert not _USE_HTTPX, 'httpx should not be available'
+          assert not _USE_HTTPX, 'httpx/httpxyz should not be available'
           assert _USE_NIQUESTS, 'niquests should be used'
           print('✓ Using niquests for async HTTP')
           "
       - name: Run async tests with niquests
         run: pytest tests/test_async_davclient.py -v
+  async-httpxyz:
+    # Test that async code works with httpxyz when niquests is not installed
+    name: async (httpxyz fallback)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - name: Install dependencies with httpxyz, without niquests
+        run: |
+          pip install --editable .[test]
+          pip uninstall -y niquests
+          pip install httpxyz
+      - name: Verify httpxyz is used
+        run: |
+          python -c "
+          from caldav.async_davclient import _USE_HTTPX, _USE_HTTPXYZ, _USE_NIQUESTS
+          assert not _USE_NIQUESTS, 'niquests should not be available'
+          assert _USE_HTTPXYZ, 'httpxyz should be used'
+          assert _USE_HTTPX, '_USE_HTTPX should be set when httpxyz is used'
+          print('✓ Using httpxyz for async HTTP')
+          "
+      - name: Run async tests with httpxyz
+        run: pytest tests/test_async_davclient.py -v
+  async-httpx:
+    # Test that async code works with plain httpx when niquests and httpxyz are not installed
+    name: async (httpx fallback)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - name: Install dependencies with httpx only
+        run: |
+          pip install --editable .[test]
+          pip uninstall -y niquests httpxyz
+      - name: Verify httpx is used
+        run: |
+          python -c "
+          from caldav.async_davclient import _USE_HTTPX, _USE_HTTPXYZ, _USE_NIQUESTS
+          assert not _USE_NIQUESTS, 'niquests should not be available'
+          assert not _USE_HTTPXYZ, 'httpxyz should not be available'
+          assert _USE_HTTPX, 'httpx should be used'
+          print('✓ Using httpx for async HTTP')
+          "
+      - name: Run async tests with httpx
+        run: pytest tests/test_async_davclient.py -v
   sync-requests:
     # Test that sync code works with requests when niquests is not installed
     name: sync (requests fallback)

caldav/async_davclient.py

@@ -18,8 +18,9 @@
     from caldav.calendarobjectresource import CalendarObjectResource
     from caldav.collection import Calendar, Principal
 
-# Try niquests first (preferred), fall back to httpx
+# Try niquests first (preferred), then httpxyz, then httpx
 _USE_HTTPX = False
+_USE_HTTPXYZ = False
 _USE_NIQUESTS = False
 _H2_AVAILABLE = False
 
@@ -34,10 +35,10 @@
 
 if not _USE_NIQUESTS:
     try:
-        import httpx
+        import httpxyz as httpx
 
+        _USE_HTTPXYZ = True
         _USE_HTTPX = True
-        # Check if h2 is available for HTTP/2 support
         try:
             import h2  # noqa: F401
 
@@ -46,6 +47,31 @@
             pass
 
         class _HttpxBearerAuth(httpx.Auth):
+            """httpx/httpxyz-compatible bearer token auth."""
+
+            def __init__(self, password: str) -> None:
+                self.password = password
+
+            def auth_flow(self, request):
+                request.headers["Authorization"] = f"Bearer {self.password}"
+                yield request
+
+    except ImportError:
+        pass
+
+if not _USE_NIQUESTS and not _USE_HTTPXYZ:
+    try:
+        import httpx
+
+        _USE_HTTPX = True
+        try:
+            import h2  # noqa: F401
+
+            _H2_AVAILABLE = True
+        except ImportError:
+            pass
+
+        class _HttpxBearerAuth(httpx.Auth):  # type: ignore[no-redef]
             """httpx-compatible bearer token auth."""
 
             def __init__(self, password: str) -> None:
@@ -60,8 +86,8 @@ def auth_flow(self, request):
 
 if not _USE_HTTPX and not _USE_NIQUESTS:
     raise ImportError(
-        "Either httpx or niquests library is required for async_davclient. "
-        "Install with: pip install httpx  (or: pip install niquests)"
+        "An async HTTP library is required for async_davclient. "
+        "Install with: pip install niquests  (or: pip install httpxyz  or: pip install httpx)"
     )
 
 
@@ -105,7 +131,7 @@ def __init__(
         proxy: str | None = None,
         username: str | None = None,
         password: str | None = None,
-        auth: Any | None = None,  # httpx.Auth or niquests.auth.AuthBase
+        auth: Any | None = None,  # httpx.Auth, httpxyz.Auth, or niquests.auth.AuthBase
         auth_type: str | None = None,
         timeout: int | None = None,
         ssl_verify_cert: bool | str = True,

pyproject.toml

@@ -83,6 +83,7 @@ test = [
   "radicale",
   "pyfakefs",
   "httpx",
+  "httpxyz",
   #"caldav_server_tester"
   "deptry>=0.24.0; python_version >= '3.10'",
 ]
@@ -101,7 +102,7 @@ namespaces = false
 ignore = ["DEP002"]  # Test dependencies (pytest, coverage, etc.) are not imported in main code
 
 [tool.deptry.per_rule_ignores]
-DEP001 = ["conf", "h2"]  # conf: Local test config, h2: Optional HTTP/2 support
+DEP001 = ["conf", "h2", "httpxyz"]  # conf: Local test config, h2: Optional HTTP/2 support, httpxyz: Optional async HTTP client
 DEP003 = ["aiohttp"]  # aiohttp: optional dep used only in caldav/testing.py (XandikosServer)
 
 [tool.ruff]