Add tests for http transport errors (#149)

---------
Co-authored-by: Christoph Pirkl <4711730+kaklakariada@users.noreply.github.com>

test/integration/http_transport_errors_test.py

@@ -0,0 +1,78 @@
+import os
+import time
+import pytest
+import shutil
+import pyexasol
+
+
+@pytest.fixture
+def dev_null():
+    with open(os.devnull, "wb") as f:
+        yield f
+
+
+@pytest.fixture
+def statement():
+    yield "SELECT * FROM USERS LIMIT 1000"
+
+
+@pytest.fixture
+def invalid_statement():
+    yield "SELECT * FROM DoesNotExist LIMIT 1000"
+
+
+@pytest.mark.etl
+@pytest.mark.exceptions
+def test_sql_error(connection, dev_null, invalid_statement):
+    def export_cb(pipe, dst, **kwargs):
+        shutil.copyfileobj(pipe, dev_null)
+
+    with pytest.raises(pyexasol.exceptions.ExaQueryError):
+        connection.export_to_callback(export_cb, None, invalid_statement)
+
+
+@pytest.mark.etl
+@pytest.mark.exceptions
+def test_abort_query(connection, dev_null, statement):
+    def export_cb(pipe, dst, **kwargs):
+        connection.abort_query()
+        # Make sure abort has time to propagate
+        time.sleep(1)
+        shutil.copyfileobj(pipe, dev_null)
+
+    with pytest.raises(pyexasol.exceptions.ExaError):
+        connection.export_to_callback(export_cb, None, statement)
+
+
+@pytest.mark.etl
+@pytest.mark.exceptions
+def test_error_in_export_callback(connection, statement):
+    error_msg = "Error from callback"
+
+    def export_cb(pipe, dst, **kwargs):
+        raise Exception(error_msg)
+
+    with pytest.raises(Exception, match=error_msg):
+        connection.export_to_callback(export_cb, None, statement)
+
+
+@pytest.mark.etl
+@pytest.mark.exceptions
+def test_error_in_import_callback(connection, statement):
+    def import_cb(pipe, src, **kwargs):
+        raise Exception()
+
+    with pytest.raises(pyexasol.exceptions.ExaQueryError):
+        connection.import_from_callback(import_cb, None, "users")
+
+
+@pytest.mark.etl
+@pytest.mark.exceptions
+def test_closed_ws_connection(connection, dev_null, statement):
+    def import_cb(pipe, src, **kwargs):
+        connection.close(disconnect=False)
+        time.sleep(1)
+        shutil.copyfileobj(pipe, dev_null)
+
+    with pytest.raises(pyexasol.exceptions.ExaError):
+        connection.import_from_callback(import_cb, None, "users")