Add test to sync using different download policies

Add basic test to sync using different download policies.

ref:#4126
https://pulp.plan.io/issues/4126

pulp_file/tests/functional/api/test_download_policies.py

@@ -0,0 +1,88 @@
+# coding=utf-8
+"""Tests for Pulp`s download policies."""
+import unittest
+
+from pulp_smash import api, config
+from pulp_smash.pulp3.constants import REPO_PATH
+from pulp_smash.pulp3.utils import (
+    gen_repo,
+    get_added_content_summary,
+    get_content_summary,
+    sync,
+)
+
+from pulp_file.tests.functional.constants import (
+    FILE_FIXTURE_SUMMARY,
+    FILE_REMOTE_PATH
+)
+from pulp_file.tests.functional.utils import gen_file_remote
+from pulp_file.tests.functional.utils import set_up_module as setUpModule  # noqa:F401
+
+
+class SyncDownloadPolicyTestCase(unittest.TestCase):
+    """Sync a repository with different download policies.
+
+    This test targets the following issue:
+
+    `Pulp #4126 <https://pulp.plan.io/issues/4126>`_
+    """
+
+    @classmethod
+    def setUpClass(cls):
+        """Create class-wide variables."""
+        cls.cfg = config.get_config()
+        cls.client = api.Client(cls.cfg, api.json_handler)
+
+    def test_on_demand(self):
+        """Sync with ``on_demand`` download policy. See :meth:`do_test`."""
+        self.do_test('on_demand')
+
+    def test_streamed(self):
+        """Sync with ``streamend`` download policy.  See :meth:`do_test`."""
+        self.do_test('streamed')
+
+    def do_test(self, download_policy):
+        """Sync repositories with the different ``download_policy``.
+
+        Do the following:
+
+        1. Create a repository, and a remote.
+        2. Assert that repository version is None.
+        3. Sync the remote.
+        4. Assert that repository version is not None.
+        5. Assert that the correct number of possible units to be downloaded
+           were shown.
+        6. Sync the remote one more time in order to create another repository
+           version.
+        7. Assert that repository version is different from the previous one.
+        8. Assert that the same number of units are shown, and after the
+           second sync no extra units should be shown, since the same remote
+           was synced again.
+        """
+        repo = self.client.post(REPO_PATH, gen_repo())
+        self.addCleanup(self.client.delete, repo['_href'])
+
+        body = gen_file_remote(**{'policy': download_policy})
+        remote = self.client.post(FILE_REMOTE_PATH, body)
+        self.addCleanup(self.client.delete, remote['_href'])
+
+        # Sync the repository.
+        self.assertIsNone(repo['_latest_version_href'])
+        sync(self.cfg, remote, repo)
+        repo = self.client.get(repo['_href'])
+
+        self.assertIsNotNone(repo['_latest_version_href'])
+        self.assertDictEqual(get_content_summary(repo), FILE_FIXTURE_SUMMARY)
+        self.assertDictEqual(
+            get_added_content_summary(repo),
+            FILE_FIXTURE_SUMMARY
+        )
+
+        # Sync the repository again.
+        latest_version_href = repo['_latest_version_href']
+        sync(self.cfg, remote, repo)
+        repo = self.client.get(repo['_href'])
+
+        self.assertNotEqual(latest_version_href, repo['_latest_version_href'])
+        self.assertDictEqual(get_content_summary(repo), FILE_FIXTURE_SUMMARY)
+        self.assertDictEqual(get_added_content_summary(repo), {})