refactor(tests): decouple unittests from integration tests (#15473)

* refactor move all tests to be under integration_tests package

* refactor decouple unittests from integration tests - commands

* add unit_tests package

* fix celery_tests.py

* fix wrong FIXTURES_DIR value

tests/integration_tests/db_engine_specs/oracle_tests.py

@@ -0,0 +1,87 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from unittest import mock
+
+import pytest
+from sqlalchemy import column
+from sqlalchemy.dialects import oracle
+from sqlalchemy.dialects.oracle import DATE, NVARCHAR, VARCHAR
+
+from superset.db_engine_specs.oracle import OracleEngineSpec
+from tests.integration_tests.db_engine_specs.base_tests import TestDbEngineSpec
+
+
+class TestOracleDbEngineSpec(TestDbEngineSpec):
+    def test_oracle_sqla_column_name_length_exceeded(self):
+        col = column("This_Is_32_Character_Column_Name")
+        label = OracleEngineSpec.make_label_compatible(col.name)
+        self.assertEqual(label.quote, True)
+        label_expected = "3b26974078683be078219674eeb8f5"
+        self.assertEqual(label, label_expected)
+
+    def test_oracle_time_expression_reserved_keyword_1m_grain(self):
+        col = column("decimal")
+        expr = OracleEngineSpec.get_timestamp_expr(col, None, "P1M")
+        result = str(expr.compile(dialect=oracle.dialect()))
+        self.assertEqual(result, "TRUNC(CAST(\"decimal\" as DATE), 'MONTH')")
+        dttm = self.get_dttm()
+
+    def test_column_datatype_to_string(self):
+        test_cases = (
+            (DATE(), "DATE"),
+            (VARCHAR(length=255), "VARCHAR(255 CHAR)"),
+            (VARCHAR(length=255, collation="utf8"), "VARCHAR(255 CHAR)"),
+            (NVARCHAR(length=128), "NVARCHAR2(128)"),
+        )
+
+        for original, expected in test_cases:
+            actual = OracleEngineSpec.column_datatype_to_string(
+                original, oracle.dialect()
+            )
+            self.assertEqual(actual, expected)
+
+    def test_fetch_data_no_description(self):
+        cursor = mock.MagicMock()
+        cursor.description = []
+        assert OracleEngineSpec.fetch_data(cursor) == []
+
+    def test_fetch_data(self):
+        cursor = mock.MagicMock()
+        result = ["a", "b"]
+        cursor.fetchall.return_value = result
+        assert OracleEngineSpec.fetch_data(cursor) == result
+
+
+@pytest.mark.parametrize(
+    "date_format,expected",
+    [
+        ("DATE", "TO_DATE('2019-01-02', 'YYYY-MM-DD')"),
+        ("DATETIME", """TO_DATE('2019-01-02T03:04:05', 'YYYY-MM-DD"T"HH24:MI:SS')"""),
+        (
+            "TIMESTAMP",
+            """TO_TIMESTAMP('2019-01-02T03:04:05.678900', 'YYYY-MM-DD"T"HH24:MI:SS.ff6')""",
+        ),
+        (
+            "timestamp",
+            """TO_TIMESTAMP('2019-01-02T03:04:05.678900', 'YYYY-MM-DD"T"HH24:MI:SS.ff6')""",
+        ),
+        ("Other", None),
+    ],
+)
+def test_convert_dttm(date_format, expected):
+    dttm = TestOracleDbEngineSpec.get_dttm()
+    assert OracleEngineSpec.convert_dttm(date_format, dttm) == expected