Add: muck/mem.py

2 files changed, 194 insertions, 0 deletions

diff --git a/muck/mem.py b/muck/mem.py
new file mode 100644
index 0000000..437085d
--- /dev/null
+++ b/muck/mem.py
@@ -0,0 +1,56 @@
+# Copyright (C) 2018  Lars Wirzenius
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import muck
+
+
+class MemoryStore:
+
+    def __init__(self):
+        self._dict = {}
+
+    def __len__(self):
+        return len(self._dict)
+
+    def as_dict(self):
+        return self._dict
+
+    def change(self, chg):
+        funcs = {
+            'create': self._create,
+            'update': self._update,
+            'delete': self._delete,
+        }
+        op = chg.get_op()
+        func = funcs[op]
+        func(chg)
+
+    def _create(self, chg):
+        rid = chg.get_id()
+        if rid in self._dict:
+            raise muck.Error('Resource {} already exists'.format(rid))
+        self._dict[rid] = (chg.get_meta(), chg.get_res())
+
+    def _update(self, chg):
+        rid = chg.get_id()
+        if rid not in self._dict:
+            raise muck.Error('Resource {} does not exist'.format(rid))
+        self._dict[rid] = (chg.get_meta(), chg.get_res())
+
+    def _delete(self, chg):
+        rid = chg.get_id()
+        if rid not in self._dict:
+            raise muck.Error('Resource {} does not exist'.format(rid))
+        del self._dict[rid]
diff --git a/muck/mem_tests.py b/muck/mem_tests.py
new file mode 100644
index 0000000..e858a33
--- /dev/null
+++ b/muck/mem_tests.py
@@ -0,0 +1,138 @@
+# Copyright (C) 2018  Lars Wirzenius
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import unittest
+
+import muck
+
+
+class MemoryStoreTests(unittest.TestCase):
+
+    def test_is_initially_empty(self):
+        ms = muck.MemoryStore()
+        self.assertEqual(len(ms), 0)
+        self.assertEqual(ms.as_dict(), {})
+
+    def test_creates_resource(self):
+        meta = {
+            'id': 'id-1',
+            'rev': 'rev-1',
+        }
+
+        res = {
+            'foo': 'bar',
+        }
+
+        chg = muck.CreateChange(meta=meta, res=res)
+        ms = muck.MemoryStore()
+        ms.change(chg)
+        self.assertEqual(len(ms), 1)
+        self.assertEqual(
+            ms.as_dict(),
+            {
+                'id-1': (meta, res),
+            })
+
+    def test_wont_create_resource_with_conflicting_id(self):
+        meta = {
+            'id': 'id-1',
+            'rev': 'rev-1',
+        }
+
+        res = {
+            'foo': 'bar',
+        }
+
+        chg = muck.CreateChange(meta=meta, res=res)
+        ms = muck.MemoryStore()
+        ms.change(chg)
+        with self.assertRaises(muck.Error):
+            ms.change(chg)
+
+    def test_updates_resource(self):
+        meta_1 = {
+            'id': 'id-1',
+            'rev': 'rev-1',
+        }
+
+        res_v1 = {
+            'foo': 'bar',
+        }
+
+        meta_2 = dict(meta_1)
+        meta_2['rev'] = 'rev-2'
+
+        res_v2 = dict(res_v1)
+        res_v2['foo'] = 'yo'
+
+        create = muck.CreateChange(meta=meta_1, res=res_v1)
+        update = muck.UpdateChange(meta=meta_2, res=res_v2)
+
+        ms = muck.MemoryStore()
+        ms.change(create)
+        ms.change(update)
+        self.assertEqual(len(ms), 1)
+        self.assertEqual(
+            ms.as_dict(),
+            {
+                'id-1': (meta_2, res_v2),
+            })
+
+    def test_refuses_to_update_resource_that_didnt_exist(self):
+        meta = {
+            'id': 'id-1',
+            'rev': 'rev-1',
+        }
+
+        res = {
+            'foo': 'bar',
+        }
+
+        update = muck.UpdateChange(meta=meta, res=res)
+
+        ms = muck.MemoryStore()
+        with self.assertRaises(muck.Error):
+            ms.change(update)
+
+    def test_deletes_resource(self):
+        meta = {
+            'id': 'id-1',
+            'rev': 'rev-1',
+        }
+
+        res = {
+            'foo': 'bar',
+        }
+
+        create = muck.CreateChange(meta=meta, res=res)
+        delete = muck.DeleteChange(meta=meta)
+
+        ms = muck.MemoryStore()
+        ms.change(create)
+        ms.change(delete)
+        self.assertEqual(len(ms), 0)
+        self.assertEqual(ms.as_dict(), {})
+
+    def test_refuses_to_delete_resource_that_doesnt_exist(self):
+        meta = {
+            'id': 'id-1',
+            'rev': 'rev-1',
+        }
+
+        delete = muck.DeleteChange(meta=meta)
+
+        ms = muck.MemoryStore()
+        with self.assertRaises(muck.Error):
+            ms.change(delete)