Clarify fetchmany rejection message: "non-negative" instead of ">= 0"

The rejection message read awkwardly at the point it fires: the guard
only triggers when the caller passes a negative size, so "must be >= 0,
got -5" reads like a contradiction. "non-negative" describes the same
constraint but scans correctly in the rejection context.
Updated the sync and async cursors together and adjusted the existing
regex pin test.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: antoineleclair

src/dqlitedbapi/aio/cursor.py

@@ -199,7 +199,7 @@ async def fetchmany(self, size: int | None = None) -> list[tuple[Any, ...]]:
         if size < 0:
             # See sync Cursor.fetchmany: silently returning [] on a
             # negative size hides caller bugs.
-            raise ProgrammingError(f"fetchmany size must be >= 0, got {size}")
+            raise ProgrammingError(f"fetchmany size must be non-negative, got {size}")
 
         result: list[tuple[Any, ...]] = []
         for _ in range(size):

src/dqlitedbapi/cursor.py

@@ -371,7 +371,7 @@ def fetchmany(self, size: int | None = None) -> list[tuple[Any, ...]]:
             # Previously ``range(-5)`` silently returned [] — hid caller
             # bugs. ``arraysize`` setter already validates >= 1; mirror
             # that here.
-            raise ProgrammingError(f"fetchmany size must be >= 0, got {size}")
+            raise ProgrammingError(f"fetchmany size must be non-negative, got {size}")
 
         result: list[tuple[Any, ...]] = []
         for _ in range(size):

tests/test_dbapi_hardening.py

@@ -113,7 +113,7 @@ def _check_thread(self) -> None: ...
         cursor = Cursor(_FakeConn())  # type: ignore[arg-type]
         cursor._description = [("x", None, None, None, None, None, None)]
         cursor._rows = [(1,), (2,)]
-        with pytest.raises(ProgrammingError, match=">= 0"):
+        with pytest.raises(ProgrammingError, match="non-negative"):
             cursor.fetchmany(-5)
         # 0 is allowed per PEP 249.
         assert cursor.fetchmany(0) == []
@@ -129,7 +129,7 @@ class _FakeAsyncConn:
         cursor._rows = [(1,), (2,)]
 
         async def _run() -> None:
-            with pytest.raises(ProgrammingError, match=">= 0"):
+            with pytest.raises(ProgrammingError, match="non-negative"):
                 await cursor.fetchmany(-3)
             assert await cursor.fetchmany(0) == []