Test whether the plugin interface is used properly

ckan/tests/functional/test_preview_interface.py

@@ -0,0 +1,48 @@
+from ckan.tests import *
+import ckan.model as model
+from ckan.lib.create_test_data import CreateTestData
+from ckan.tests.pylons_controller import PylonsTestCase
+import ckan.plugins as plugins
+import ckan.controllers.package as package
+import ckan.tests.mock_plugin as mock
+
+
+class MockResourcePreviewExtension(mock.MockSingletonPlugin):
+    plugins.implements(plugins.IResourcePreview)
+
+    def __init__(self):
+        from collections import defaultdict
+        self.calls = defaultdict(int)
+
+    def can_preview(self, data_dict):
+        self.calls['can_preview'] += 1
+        return True
+
+    def setup_template_variables(self, context, data_dict):
+        self.calls['setup_template_variables'] += 1
+
+    def preview_template(self, context, data_dict):
+        self.calls['preview_template'] += 1
+
+
+class TestPluggablePreviews(object):
+    @classmethod
+    def setup_class(cls):
+        PylonsTestCase.setup_class()
+        CreateTestData.create()
+
+    @classmethod
+    def teardown_class(cls):
+        model.repo.rebuild_db()
+
+    def test_hook(self):
+        plugin = MockResourcePreviewExtension()
+        plugins.load(plugin)
+
+        testpackage = model.Package.get('annakarenina')
+
+        pc = package.PackageController()
+        pc.resource_datapreview(testpackage.id, testpackage.resources[0])
+
+        assert plugin.calls['can_preview'] == 1, plugin.calls
+        plugins.unload(plugin)