[1/3] Add support for multiple exchanges with ccxt (objectified version) (#585)

* remove obsolete helper functions and make _state a public member.

* remove function assertions

* revert worker() changes

* Update pytest from 3.4.2 to 3.5.0

* Adapt exchange functions to ccxt API
Remove get_market_summaries and get_wallet_health, add exception handling

* Add NetworkException

* Change pair format in constants.py

* Add tests for exchange functions that comply with ccxt

* Remove bittrex tests

* Remove Bittrex and Interface classes

* Add retrier decorator

* Remove cache from get_ticker

* Remove unused and duplicate imports

* Add keyword arguments for get_fee

* Implement 'get_pair_detail_url'

* Change get_ticker_history format to ccxt format

* Fix exchange urls dict, don't need to initialize exchanges

* Add "Using Exchange ..." logging line

freqtrade/tests/test_freqtradebot.py

@@ -84,8 +84,6 @@ def test_freqtradebot_object() -> None:
     Test the FreqtradeBot object has the mandatory public methods
     """
     assert hasattr(FreqtradeBot, 'worker')
-    assert hasattr(FreqtradeBot, 'get_state')
-    assert hasattr(FreqtradeBot, 'update_state')
     assert hasattr(FreqtradeBot, 'clean')
     assert hasattr(FreqtradeBot, 'create_trade')
     assert hasattr(FreqtradeBot, 'get_target_bid')
@@ -103,12 +101,12 @@ def test_freqtradebot(mocker, default_conf) -> None:
     Test __init__, _init_modules, update_state, and get_state methods
     """
     freqtrade = get_patched_freqtradebot(mocker, default_conf)
-    assert freqtrade.get_state() is State.RUNNING
+    assert freqtrade.state is State.RUNNING
 
     conf = deepcopy(default_conf)
     conf.pop('initial_state')
     freqtrade = FreqtradeBot(conf)
-    assert freqtrade.get_state() is State.STOPPED
+    assert freqtrade.state is State.STOPPED
 
 
 def test_clean(mocker, default_conf, caplog) -> None:
@@ -119,10 +117,10 @@ def test_clean(mocker, default_conf, caplog) -> None:
     mocker.patch('freqtrade.persistence.cleanup', mock_cleanup)
 
     freqtrade = get_patched_freqtradebot(mocker, default_conf)
-    assert freqtrade.get_state() == State.RUNNING
+    assert freqtrade.state == State.RUNNING
 
     assert freqtrade.clean()
-    assert freqtrade.get_state() == State.STOPPED
+    assert freqtrade.state == State.STOPPED
     assert log_has('Stopping trader and cleaning up modules...', caplog.record_tuples)
     assert mock_cleanup.call_count == 1
 
@@ -151,7 +149,7 @@ def test_worker_stopped(mocker, default_conf, caplog) -> None:
     mock_sleep = mocker.patch('time.sleep', return_value=None)
 
     freqtrade = get_patched_freqtradebot(mocker, default_conf)
-    freqtrade.update_state(State.STOPPED)
+    freqtrade.state = State.STOPPED
     state = freqtrade.worker(old_state=State.RUNNING)
     assert state is State.STOPPED
     assert log_has('Changing state to: STOPPED', caplog.record_tuples)
@@ -262,7 +260,7 @@ def test_create_trade(default_conf, ticker, limit_buy_order, mocker) -> None:
     assert trade.stake_amount == 0.001
     assert trade.is_open
     assert trade.open_date is not None
-    assert trade.exchange == 'BITTREX'
+    assert trade.exchange == 'bittrex'
 
     # Simulate fulfilled LIMIT_BUY order for trade
     trade.update(limit_buy_order)
@@ -424,7 +422,7 @@ def test_process_trade_creation(default_conf, ticker, limit_buy_order,
     assert trade.stake_amount == default_conf['stake_amount']
     assert trade.is_open
     assert trade.open_date is not None
-    assert trade.exchange == "BITTREX"
+    assert trade.exchange == 'bittrex'
     assert trade.open_rate == 0.00001099
     assert trade.amount == 90.99181073703367
 
@@ -471,11 +469,11 @@ def test_process_operational_exception(default_conf, ticker, health, mocker) ->
         buy=MagicMock(side_effect=OperationalException)
     )
     freqtrade = FreqtradeBot(default_conf, create_engine('sqlite://'))
-    assert freqtrade.get_state() == State.RUNNING
+    assert freqtrade.state == State.RUNNING
 
     result = freqtrade._process()
     assert result is False
-    assert freqtrade.get_state() == State.STOPPED
+    assert freqtrade.state == State.STOPPED
     assert 'OperationalException' in msg_mock.call_args_list[-1][0][0]