Close dbapi test-coverage gaps

ISSUE-25 — fetchmany edge cases: size=0 returns empty, oversized
returns remaining, default uses arraysize, cursor iteration drains,
fetchone+fetchmany/fetchall mix behaves correctly, fetch before a
query raises.

ISSUE-26 — large data: 5k-row SELECT (forces continuation frames on
most server chunk sizes), 2 MiB BLOB round-trip.

ISSUE-27 — Unicode in identifiers (café table, ☕ column name) and
non-BMP codepoints (U+1F600 emoji) in TEXT values.

ISSUE-28 — multi-statement SQL rejection with "nonempty statement
tail". dqlite deviates from stdlib sqlite3 here; pinning the error
so regressions can't silently change the behavior.

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

Author: antoineleclair

tests/integration/test_misc_coverage.py

@@ -0,0 +1,95 @@
+"""Integration tests for previously-uncovered territory.
+
+- ISSUE-26: large result set (forces continuation frames) + large BLOB.
+- ISSUE-27: Unicode in identifiers + emoji in TEXT.
+- ISSUE-28: multi-statement SQL is rejected with a specific error.
+"""
+
+import dqliteclient.exceptions
+import pytest
+
+from dqlitedbapi import connect
+from dqlitedbapi.exceptions import OperationalError
+
+
+@pytest.mark.integration
+class TestLargeData:
+    def test_large_result_set_round_trips(self, cluster_address: str) -> None:
+        """Insert 5k rows and read them all back; exercises continuation frames
+        on most server chunk sizes."""
+        with connect(cluster_address, database="test_large") as conn:
+            c = conn.cursor()
+            c.execute("DROP TABLE IF EXISTS many")
+            c.execute("CREATE TABLE many (i INTEGER PRIMARY KEY, s TEXT)")
+            for i in range(5000):
+                c.execute("INSERT INTO many (i, s) VALUES (?, ?)", [i, f"row-{i}"])
+            conn.commit()
+
+            c.execute("SELECT i, s FROM many ORDER BY i")
+            rows = c.fetchall()
+            assert len(rows) == 5000
+            assert rows[0] == (0, "row-0")
+            assert rows[-1] == (4999, "row-4999")
+            c.execute("DROP TABLE many")
+
+    def test_multi_megabyte_blob(self, cluster_address: str) -> None:
+        """A 2 MiB BLOB round-trips byte-for-byte."""
+        payload = bytes(range(256)) * 8192  # 2 MiB of 0x00..0xFF pattern
+        assert len(payload) == 2 * 1024 * 1024
+        with connect(cluster_address, database="test_blob") as conn:
+            c = conn.cursor()
+            c.execute("DROP TABLE IF EXISTS big_blob")
+            c.execute("CREATE TABLE big_blob (id INTEGER PRIMARY KEY, data BLOB)")
+            c.execute("INSERT INTO big_blob (data) VALUES (?)", [payload])
+            conn.commit()
+            c.execute("SELECT data FROM big_blob")
+            (value,) = c.fetchone()
+            assert value == payload
+            c.execute("DROP TABLE big_blob")
+
+
+@pytest.mark.integration
+class TestUnicode:
+    def test_unicode_identifier_and_emoji_value(self, cluster_address: str) -> None:
+        with connect(cluster_address, database="test_unicode") as conn:
+            c = conn.cursor()
+            c.execute('DROP TABLE IF EXISTS "café"')
+            c.execute('CREATE TABLE "café" (id INTEGER PRIMARY KEY, "☕" TEXT)')
+            c.execute('INSERT INTO "café" ("☕") VALUES (?)', ["hello 🚀 world"])
+            conn.commit()
+            c.execute('SELECT "☕" FROM "café"')
+            (value,) = c.fetchone()
+            assert value == "hello 🚀 world"
+            assert c.description is not None
+            assert c.description[0][0] == "☕"
+            c.execute('DROP TABLE "café"')
+
+    def test_non_bmp_codepoint_round_trip(self, cluster_address: str) -> None:
+        """4-byte UTF-8 codepoint survives the wire round-trip."""
+        grinning = "\U0001f600"  # 😀
+        payload = grinning * 1000  # 4000 bytes of non-BMP codepoints
+        with connect(cluster_address, database="test_non_bmp") as conn:
+            c = conn.cursor()
+            c.execute("DROP TABLE IF EXISTS nbmp")
+            c.execute("CREATE TABLE nbmp (id INTEGER PRIMARY KEY, s TEXT)")
+            c.execute("INSERT INTO nbmp (s) VALUES (?)", [payload])
+            conn.commit()
+            c.execute("SELECT s FROM nbmp")
+            (value,) = c.fetchone()
+            assert value == payload
+            c.execute("DROP TABLE nbmp")
+
+
+@pytest.mark.integration
+class TestMultiStatementRejection:
+    def test_semicolon_separated_select_rejected(self, cluster_address: str) -> None:
+        """dqlite rejects multi-statement SQL — a real deviation from stdlib
+        sqlite3 that applications commonly trip over. Pinning the error so
+        regressions don't silently change the behavior."""
+        # The error class is dqliteclient.OperationalError today (the
+        # DBAPI doesn't wrap); either is acceptable for now.
+        expected = (OperationalError, dqliteclient.exceptions.OperationalError)
+        with connect(cluster_address, database="test_multi_stmt") as conn:
+            c = conn.cursor()
+            with pytest.raises(expected, match="nonempty statement tail"):
+                c.execute("SELECT 1; SELECT 2;")

tests/test_fetchmany_edges.py

@@ -0,0 +1,64 @@
+"""PEP 249 fetchmany edge cases (ISSUE-25)."""
+
+from unittest.mock import AsyncMock, MagicMock
+
+import pytest
+
+from dqlitedbapi.cursor import Cursor
+
+
+def _seeded_cursor(rows: list[tuple[int, ...]]) -> Cursor:
+    """Build a Cursor with ``rows`` already materialised as a result set.
+
+    Bypasses the event-loop layer — these are pure fetch-path edge
+    cases that don't need a live cluster.
+    """
+    conn = MagicMock()
+    conn._get_async_connection = AsyncMock()
+    conn._run_sync = MagicMock()
+    c = Cursor(conn)
+    c._rows = rows  # type: ignore[assignment]
+    c._row_index = 0
+    c._description = [("id", None, None, None, None, None, None)]
+    c._rowcount = len(rows)
+    return c
+
+
+class TestFetchmanyEdges:
+    def test_fetchmany_zero_returns_empty(self) -> None:
+        c = _seeded_cursor([(1,), (2,), (3,)])
+        assert c.fetchmany(0) == []
+        # didn't advance
+        assert c._row_index == 0
+
+    def test_fetchmany_larger_than_remaining_returns_all_remaining(self) -> None:
+        c = _seeded_cursor([(1,), (2,), (3,)])
+        assert c.fetchmany(100) == [(1,), (2,), (3,)]
+        assert c._row_index == 3
+
+    def test_fetchmany_default_uses_arraysize(self) -> None:
+        c = _seeded_cursor([(1,), (2,), (3,)])
+        c.arraysize = 2
+        assert c.fetchmany() == [(1,), (2,)]
+
+    def test_for_row_in_cursor_iterates_all(self) -> None:
+        c = _seeded_cursor([(1,), (2,), (3,)])
+        collected = list(c)
+        assert collected == [(1,), (2,), (3,)]
+
+    def test_fetchone_then_fetchmany_continues(self) -> None:
+        c = _seeded_cursor([(1,), (2,), (3,)])
+        assert c.fetchone() == (1,)
+        assert c.fetchmany(10) == [(2,), (3,)]
+
+    def test_fetchall_after_partial_fetch(self) -> None:
+        c = _seeded_cursor([(1,), (2,), (3,)])
+        c.fetchone()
+        assert c.fetchall() == [(2,), (3,)]
+
+    def test_fetch_on_no_result_set_raises(self) -> None:
+        conn = MagicMock()
+        c = Cursor(conn)
+        # No execute called → description is None.
+        with pytest.raises(Exception, match="No result set"):
+            c.fetchone()