[AIRFLOW-3189] Remove schema from get_uri response if None (apache#6833)

"None" was appended to uri if schema=None. Check was added if
schema is None.

airflow/hooks/dbapi_hook.py

@@ -74,8 +74,11 @@ def get_uri(self):
         host = conn.host
         if conn.port is not None:
             host += ':{port}'.format(port=conn.port)
-        return '{conn.conn_type}://{login}{host}/{conn.schema}'.format(
+        uri = '{conn.conn_type}://{login}{host}/'.format(
             conn=conn, login=login, host=host)
+        if conn.schema:
+            uri += conn.schema
+        return uri
 
     def get_sqlalchemy_engine(self, engine_kwargs=None):
         if engine_kwargs is None:

tests/hooks/test_dbapi_hook.py

@@ -22,6 +22,7 @@
 from unittest import mock
 
 from airflow.hooks.dbapi_hook import DbApiHook
+from airflow.models import Connection
 
 
 class TestDbApiHook(unittest.TestCase):
@@ -149,3 +150,25 @@ def test_insert_rows_commit_every(self):
         sql = "INSERT INTO {}  VALUES (%s)".format(table)
         for row in rows:
             self.cur.execute.assert_any_call(sql, row)
+
+    def test_get_uri_schema_not_none(self):
+        self.db_hook.get_connection = mock.MagicMock(return_value=Connection(
+            conn_type="conn_type",
+            host="host",
+            login="login",
+            password="password",
+            schema="schema",
+            port=1
+        ))
+        self.assertEqual("conn_type://login:password@host:1/schema", self.db_hook.get_uri())
+
+    def test_get_uri_schema_none(self):
+        self.db_hook.get_connection = mock.MagicMock(return_value=Connection(
+            conn_type="conn_type",
+            host="host",
+            login="login",
+            password="password",
+            schema=None,
+            port=1
+        ))
+        self.assertEqual("conn_type://login:password@host:1/", self.db_hook.get_uri())