Allow to run tests in parallel

Before:
	Ran 271 tests in 794.271s

After:
	Ran 271 tests in 85.712s

Author: erezsh

tests/test_api.py

@@ -15,6 +15,7 @@ def setUpClass(cls):
         cls.preql = preql.Preql(TEST_MYSQL_CONN_STRING)
 
     def setUp(self) -> None:
+        self.preql = preql.Preql(TEST_MYSQL_CONN_STRING)
         self.preql(
             r"""
             table test_api {

tests/test_database_types.py

@@ -274,8 +274,12 @@ def test_types(self, source_db, target_db, source_type, target_type, type_catego
         self.connections = [self.src_conn, self.dst_conn]
         sample_values = TYPE_SAMPLES[type_category]
 
-        src_table_path = src_conn.parse_table_name("src")
-        dst_table_path = dst_conn.parse_table_name("dst")
+        # Limit in MySQL is 64
+        src_table_name = f"src_{self._testMethodName[:60]}"
+        dst_table_name = f"dst_{self._testMethodName[:60]}"
+
+        src_table_path = src_conn.parse_table_name(src_table_name)
+        dst_table_path = dst_conn.parse_table_name(dst_table_name)
         src_table = src_conn.quote(".".join(src_table_path))
         dst_table = dst_conn.quote(".".join(dst_table_path))
 

tests/test_diff_tables.py

@@ -33,8 +33,24 @@ def tearDownClass(cls):
         cls.connection.close()
 
 
+    # Fallback for test runners that doesn't support setUpClass/tearDownClass
+    def setUp(self) -> None:
+        if not hasattr(self, 'connection'):
+            self.setUpClass.__func__(self)
+            self.private_connection = True
+
+        return super().setUp()
+
+    def tearDown(self) -> None:
+        if hasattr(self, 'private_connection'):
+            self.tearDownClass.__func__(self)
+
+        return super().tearDown()
+
+
 class TestDates(TestWithConnection):
     def setUp(self):
+        super().setUp()
         self.connection.query("DROP TABLE IF EXISTS a", None)
         self.connection.query("DROP TABLE IF EXISTS b", None)
         self.preql(
@@ -110,6 +126,7 @@ def test_offset(self):
 
 class TestDiffTables(TestWithConnection):
     def setUp(self):
+        super().setUp()
         self.connection.query("DROP TABLE IF EXISTS ratings_test", None)
         self.connection.query("DROP TABLE IF EXISTS ratings_test2", None)
         self.preql.load("./tests/setup.pql")
@@ -221,9 +238,9 @@ def test_diff_sorted_by_key(self):
 
 class TestTableSegment(TestWithConnection):
     def setUp(self) -> None:
+        super().setUp()
         self.table = TableSegment(self.connection, ("ratings_test",), "id", "timestamp")
         self.table2 = TableSegment(self.connection, ("ratings_test2",), "id", "timestamp")
-        return super().setUp()
 
     def test_table_segment(self):
         early = datetime.datetime(2021, 1, 1, 0, 0)