ci: run unit tests in CI

Unit tests (tests/unit/) were never run in CI — only integration tests
that require a running Scylla cluster.  Since unit tests use mocks and
have no external dependencies, they are fast and cheap to run, and would
have caught regressions like the missing scope validation in
wait_for_schema_agreement (#917) and the error accumulation bug in
_set_keyspace_for_all_pools (#915).

Mark the two pre-existing test failures as xfail (referencing their fix
PRs) so they don't block this change while the fixes are pending.

Author: mykaul

.github/workflows/integration-tests.yml

@@ -77,6 +77,9 @@ jobs:
     - name: Build driver
       run: uv sync
 
+    - name: Unit tests
+      run: uv run pytest tests/unit/test_*.py -x
+
     - name: Cache Scylla download
       uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
       with:

tests/unit/test_cluster.py

@@ -591,13 +591,15 @@ def test_wait_for_schema_agreement_cluster_scope_excludes_hosts_with_unknown_sta
         assert self._host_query_count(session, hosts[0]) == 0
         assert self._host_query_count(session, hosts[1]) == 1
 
+    @pytest.mark.xfail(reason="scope validation not implemented (#917)", strict=False)
     @mock_session_pools
     def test_wait_for_schema_agreement_rejects_unknown_scope(self, *_):
         session, _, _ = self._new_schema_agreement_session(["a"])
 
         with pytest.raises(ValueError):
             session.wait_for_schema_agreement(wait_time=1, scope='planet')
 
+    @pytest.mark.xfail(reason="_set_keyspace_for_all_pools passes only last pool errors (#915)", strict=False)
     @mock_session_pools
     def test_set_keyspace_for_all_pools_reports_all_errors(self, *_):
         cluster = Cluster()