Add test for clean argument of Updater.start_polling/webhook (#2002)

* added test for 'clean' argument passed to 'start_polling()'

* remove TODO

* prettify

* remove bool from func name

* improve name-ing of fake update func

* cleanup class and nameing

* replace while for for

* swap valueerror for runtimeerror

* remove all other code to reduce testing

* add comments

* don't raise error, complete cycle and assert

* remove inf loop protection

* Revert "remove all other code to reduce testing"

This reverts commit 4566a1debd.

* remove error parametrization

* remove comment

* remove pass from class

* rename update_id to offset as the original get_updates() takes argument offset (which is the update_id)

* rename test func to match original func

* fix comment

* shorten for loop

* mock get_updates() behavior when 'offset' is passed. Assert with get_updates()

* remove other functions to reduce testing

* replicate original get_updates()

* move fakeupdate class and list creation outside get_updates and store in var

* loop from 0 to make update_id consistant w array key, just easier to debug

* update comments

* Revert "remove other functions to reduce testing"

This reverts commit 1fb498a6cc.

* fix typo

* Revert "fix typo"

This reverts commit ade9fec609.

* Revert "Revert "remove other functions to reduce testing""

This reverts commit 734de1371c.

* Revert "update comments"

This reverts commit f3a032e75e.

* Revert "loop from 0 to make update_id consistant w array key, just easier to debug"

This reverts commit 0c6881d8a1.

* Revert "move fakeupdate class and list creation outside get_updates and store in var"

This reverts commit 71de999300.

* Revert "replicate original get_updates()"

This reverts commit 5d0710ac3a.

* Revert "remove other functions to reduce testing"

This reverts commit 1fb498a6cc.

* Revert "mock get_updates() behavior when 'offset' is passed. Assert with get_updates()"

This reverts commit 8c727ba1e8.

* loop from 0 to make update_id consistant w array key, for consitency

Co-authored-by: ikkemaniac <ikkemaniac@localhost>

tests/test_updater.py

@@ -75,6 +75,7 @@ class TestUpdater:
     attempts = 0
     err_handler_called = Event()
     cb_handler_called = Event()
+    offset = 0
 
     @pytest.fixture(autouse=True)
     def reset(self):
@@ -92,8 +93,6 @@ class TestUpdater:
         self.received = update.message.text
         self.cb_handler_called.set()
 
-    # TODO: test clean= argument of Updater._bootstrap
-
     @pytest.mark.parametrize(('error',),
                              argvalues=[(TelegramError('Test Error 2'),),
                                         (Unauthorized('Test Unauthorized'),)],
@@ -331,6 +330,42 @@ class TestUpdater:
             updater._bootstrap(retries, False, 'path', None, bootstrap_interval=0)
         assert self.attempts == attempts
 
+    def test_bootstrap_clean_updates(self, monkeypatch, updater):
+        clean = True
+        expected_id = 4
+        self.offset = 0
+
+        def get_updates(*args, **kwargs):
+            # we're hitting this func twice
+            # 1. no args, return list of updates
+            # 2. with 1 arg, int => if int == expected_id => test successful
+
+            # case 2
+            # 2nd call from bootstrap____clean
+            # we should be called with offset = 4
+            # save value passed in self.offset for assert down below
+            if len(args) > 0:
+                self.offset = int(args[0])
+                return []
+
+            class FakeUpdate():
+                def __init__(self, update_id):
+                    self.update_id = update_id
+
+            # case 1
+            # return list of obj's
+
+            # build list of fake updates
+            # returns list of 4 objects with
+            # update_id's 0, 1, 2 and 3
+            return [FakeUpdate(i) for i in range(0, expected_id)]
+
+        monkeypatch.setattr(updater.bot, 'get_updates', get_updates)
+
+        updater.running = True
+        updater._bootstrap(1, clean, None, None, bootstrap_interval=0)
+        assert self.offset == expected_id
+
     @flaky(3, 1)
     def test_webhook_invalid_posts(self, updater):
         ip = '127.0.0.1'