fix: _resolve_pool_knobs preserves explicit 0/0.0 via is-None checks

Caller-provided falsy values (max_conns_per_host=0, idle_timeout=0.0)
were silently replaced with spec defaults because of the 'getattr(...)
or DEFAULT_*' pattern. Switch to 'is None' so the resolver only
substitutes a default when the attribute is missing or explicitly None.

Adds TestResolvePoolKnobsExplicitZero with three cases: explicit 0
preserved, missing attrs fall back, explicit None falls back.

Author: mogita

getstream/base.py

@@ -45,11 +45,17 @@ def _resolve_pool_knobs(obj):
     fall back to spec defaults. Top-level ``Stream``/``AsyncStream`` sets
     them on ``self`` before calling ``super().__init__()``, so a directly
     instantiated sub-client (or test fixture) still gets sane values.
+
+    `is None` (not truthiness) so an explicit `0` / `0.0` from the caller is
+    preserved rather than silently swapped for a default.
     """
+    max_conns_per_host = getattr(obj, "max_conns_per_host", None)
+    idle_timeout = getattr(obj, "idle_timeout", None)
+    connect_timeout = getattr(obj, "connect_timeout", None)
     return (
-        getattr(obj, "max_conns_per_host", None) or DEFAULT_MAX_CONNS_PER_HOST,
-        getattr(obj, "idle_timeout", None) or DEFAULT_IDLE_TIMEOUT,
-        getattr(obj, "connect_timeout", None) or DEFAULT_CONNECT_TIMEOUT,
+        DEFAULT_MAX_CONNS_PER_HOST if max_conns_per_host is None else max_conns_per_host,
+        DEFAULT_IDLE_TIMEOUT if idle_timeout is None else idle_timeout,
+        DEFAULT_CONNECT_TIMEOUT if connect_timeout is None else connect_timeout,
     )
 
 

tests/test_http_client.py

@@ -468,6 +468,59 @@ async def test_per_call_timeout_reaches_httpx(self):
 # ── validation ───────────────────────────────────────────────────────
 
 
+class TestResolvePoolKnobsExplicitZero:
+    """`_resolve_pool_knobs` must use `is None`, not truthiness, so callers
+    who deliberately pass `0` / `0.0` get their value back unchanged.
+    Regression test for the falsy-fallback bug flagged in CHA-2956 review.
+    """
+
+    def test_explicit_zero_preserved(self):
+        from getstream.base import _resolve_pool_knobs
+
+        class Obj:
+            max_conns_per_host = 0
+            idle_timeout = 0.0
+            connect_timeout = 0.0
+
+        assert _resolve_pool_knobs(Obj()) == (0, 0.0, 0.0)
+
+    def test_missing_attrs_fall_back_to_defaults(self):
+        from getstream.base import (
+            _resolve_pool_knobs,
+            DEFAULT_MAX_CONNS_PER_HOST,
+            DEFAULT_IDLE_TIMEOUT,
+            DEFAULT_CONNECT_TIMEOUT,
+        )
+
+        class Obj:
+            pass
+
+        assert _resolve_pool_knobs(Obj()) == (
+            DEFAULT_MAX_CONNS_PER_HOST,
+            DEFAULT_IDLE_TIMEOUT,
+            DEFAULT_CONNECT_TIMEOUT,
+        )
+
+    def test_none_attrs_fall_back_to_defaults(self):
+        from getstream.base import (
+            _resolve_pool_knobs,
+            DEFAULT_MAX_CONNS_PER_HOST,
+            DEFAULT_IDLE_TIMEOUT,
+            DEFAULT_CONNECT_TIMEOUT,
+        )
+
+        class Obj:
+            max_conns_per_host = None
+            idle_timeout = None
+            connect_timeout = None
+
+        assert _resolve_pool_knobs(Obj()) == (
+            DEFAULT_MAX_CONNS_PER_HOST,
+            DEFAULT_IDLE_TIMEOUT,
+            DEFAULT_CONNECT_TIMEOUT,
+        )
+
+
 class TestValidation:
     def test_transport_and_http_client_mutually_exclusive(self):
         with pytest.raises(ValueError, match="Cannot specify both"):