[#642] Refactor and fix Datastore tests

Datastore is a SingletonPlugin, so it doesn't matter if we call
plugin.DatastorePlugin() many times: we always end up with the same instance.
I've added a workaround that, first, saves and unloads the current datastore
instance, then sets:

  pyutilib.component.core.PluginGlobals.singleton_services()[plugin.DatastorePlugin] = True

This will make plugin.DatastorePlugin not be a Singleton anymore, so any
subsequent calls to ckan.plugins.load('datastore') will create a new instance.
Then, in the next line, we create a new DatastorePlugin instance by loading
it, and save it into self.p and
pyutilib.component.core.PluginGlobals.singleton_services()[plugin.DatastorePlugin].
This turns DatastorePlugin into a Singleton again, and subsequent calls to
ckan.plugins.load('datastore') will return this new instance instead.

Then, in the teardown, we unload the current the datastore, which gets rid of
our test instance, and put the original datastore back in its place, so the
environment before setUp() is the same as after tearDown().

For InvalidUrlsOrPermissionsException, what I wanted was a way to check if
_check_urls_and_permissions() failed. I did this by overloading _log_or_raise()
with an unique Exception, and checking if it's raised. If so, I guarantee that
_log_or_raise() was called. This feels like too much boilerplate, but we don't
have a stub/mock library, so we have to write it.

Conflicts:
	ckanext/datastore/tests/test_configure.py

ckanext/datastore/tests/test_configure.py

@@ -1,22 +1,24 @@
 import unittest
-import ckan.plugins as p
-from nose.tools import raises
+import nose.tools
+import pyutilib.component.core
 
+import ckan.plugins
 import ckanext.datastore.plugin as plugin
 
-
 class TestConfiguration(unittest.TestCase):
     def setUp(self):
-        self.p = p.load('datastore')
+        self._original_plugin = ckan.plugins.unload('datastore')
+        pyutilib.component.core.PluginGlobals.singleton_services()[plugin.DatastorePlugin] = True
+        self.p = pyutilib.component.core.PluginGlobals.singleton_services()[plugin.DatastorePlugin] = ckan.plugins.load('datastore')
 
     def tearDown(self):
-        p.unload('datastore')
+        ckan.plugins.unload('datastore')
+        pyutilib.component.core.PluginGlobals.singleton_services()[plugin.DatastorePlugin] = self._original_plugin
 
     def test_legacy_mode_default(self):
         assert not self.p.legacy_mode
 
     def test_set_legacy_mode(self):
-        assert not self.p.legacy_mode
         c = {
             'sqlalchemy.url': 'bar',
             'ckan.datastore.write_url': 'foo'
@@ -47,65 +49,67 @@ def test_same_ckan_and_datastore_db(self):
         self.p.ckan_url = 'postgresql://u:pass@localhost/ckan'
         assert not self.p._same_ckan_and_datastore_db()
 
+    def test_setup_plugin_for_check_urls_and_permissions_tests_should_leave_the_plugin_in_a_valid_state(self):
+        self.setUp_plugin_for_check_urls_and_permissions_tests()
+        self.p._check_urls_and_permissions() # Should be OK
 
-class TestCheckUrlsAndPermissions(unittest.TestCase):
-    def setUp(self):
-        self.p = p.load('datastore')
+    def test_check_urls_and_permissions_requires_different_ckan_and_datastore_dbs(self):
+        self.setUp_plugin_for_check_urls_and_permissions_tests()
 
-        self.p.legacy_mode = False
+        self.p._same_ckan_and_datastore_db = lambda: False
+        self.p._check_urls_and_permissions() # Should be OK
 
-        # initialize URLs
-        self.p.ckan_url = 'postgresql://u:pass@localhost/ckan'
-        self.p.write_url = 'postgresql://u:pass@localhost/ds'
-        self.p.read_url = 'postgresql://u2:pass@localhost/ds'
+        self.p._same_ckan_and_datastore_db = lambda: True
+        nose.tools.assert_raises(InvalidUrlsOrPermissionsException, self.p._check_urls_and_permissions)
 
-        # initialize mock for privileges check
-        def true_privileges_mock():
-            return True
-        self.p._read_connection_has_correct_privileges = true_privileges_mock
+    def test_check_urls_and_permissions_requires_different_read_and_write_urls_when_not_in_legacy_mode(self):
+        self.setUp_plugin_for_check_urls_and_permissions_tests()
+        self.p.legacy_mode = False
 
-        def raise_datastore_exception(message):
-            raise plugin.DatastoreException(message)
-        self.p._log_or_raise = raise_datastore_exception
+        self.p._same_read_and_write_url = lambda: False
+        self.p._check_urls_and_permissions() # Should be OK
 
-    def tearDown(self):
-        p.unload('datastore')
+        self.p._same_read_and_write_url = lambda: True
+        nose.tools.assert_raises(InvalidUrlsOrPermissionsException, self.p._check_urls_and_permissions)
 
-    def test_everything_correct_does_not_raise(self):
-        self.p._check_urls_and_permissions()
+    def test_check_urls_and_permissions_doesnt_require_different_read_and_write_urls_when_in_legacy_mode(self):
+        self.setUp_plugin_for_check_urls_and_permissions_tests()
+        self.p.legacy_mode = True
 
-    @raises(plugin.DatastoreException)
-    def test_raises_when_ckan_and_datastore_db_are_the_same(self):
-        self.p.read_url = 'postgresql://u2:pass@localhost/ckan'
-        self.p.ckan_url = 'postgresql://u:pass@localhost/ckan'
+        self.p._same_read_and_write_url = lambda: False
+        self.p._check_urls_and_permissions() # Should be OK
 
-        self.p._check_urls_and_permissions()
+        self.p._same_read_and_write_url = lambda: True
+        self.p._check_urls_and_permissions() # Should be OK
 
-    @raises(plugin.DatastoreException)
-    def test_raises_when_same_read_and_write_url(self):
-        self.p.read_url = 'postgresql://u:pass@localhost/ds'
-        self.p.write_url = 'postgresql://u:pass@localhost/ds'
+    def test_check_urls_and_permissions_requires_read_connection_with_correct_privileges_when_not_in_legacy_mode(self):
+        self.setUp_plugin_for_check_urls_and_permissions_tests()
+        self.p.legacy_mode = False
 
-        self.p._check_urls_and_permissions()
+        self.p._read_connection_has_correct_privileges = lambda: True
+        self.p._check_urls_and_permissions() # Should be OK
 
-    def test_same_read_and_write_url_in_legacy_mode(self):
-        self.p.read_url = 'postgresql://u:pass@localhost/ds'
-        self.p.write_url = 'postgresql://u:pass@localhost/ds'
+        self.p._read_connection_has_correct_privileges = lambda: False
+        nose.tools.assert_raises(InvalidUrlsOrPermissionsException, self.p._check_urls_and_permissions)
+
+    def test_check_urls_and_permissions_doesnt_care_about_read_connection_privileges_when_in_legacy_mode(self):
+        self.setUp_plugin_for_check_urls_and_permissions_tests()
         self.p.legacy_mode = True
 
-        self.p._check_urls_and_permissions()
+        self.p._read_connection_has_correct_privileges = lambda: True
+        self.p._check_urls_and_permissions() # Should be OK
+
+        self.p._read_connection_has_correct_privileges = lambda: False
+        self.p._check_urls_and_permissions() # Should be OK
 
-    @raises(plugin.DatastoreException)
-    def test_raises_when_we_have_write_permissions(self):
-        def false_privileges_mock():
-            return False
-        self.p._read_connection_has_correct_privileges = false_privileges_mock
-        self.p._check_urls_and_permissions()
+    def setUp_plugin_for_check_urls_and_permissions_tests(self):
+        def _raise_invalid_urls_or_permissions_exception(message):
+            raise InvalidUrlsOrPermissionsException(message)
 
-    def test_have_write_permissions_in_legacy_mode(self):
-        def false_privileges_mock():
-            return False
-        self.p._read_connection_has_correct_privileges = false_privileges_mock
+        self.p._same_ckan_and_datastore_db = lambda: False
         self.p.legacy_mode = True
+        self.p._same_read_and_write_url = lambda: False
+        self.p._read_connection_has_correct_privileges = lambda: True
+        self.p._log_or_raise = _raise_invalid_urls_or_permissions_exception
 
-        self.p._check_urls_and_permissions()
+class InvalidUrlsOrPermissionsException(Exception): pass