Del and contains for DB

nkms/db.py

@@ -23,7 +23,20 @@ class DB(object):
 
     def __getitem__(self, key):
         with self.db.begin(write=False) as tx:
-            return tx.get(key)
+            result = tx.get(key)
+            if result is None:
+                raise KeyError(key)
+            else:
+                return result
+
+    def __delitem__(self, key):
+        with self.db.begin(write=True) as tx:
+            tx.pop(key)
+
+    def __contains__(self, key):
+        with self.db.begin(write=False) as tx:
+            cursor = tx.cursor()
+            return cursor.set_key(key)
 
     def close(self):
         self.db.close()

tests/test_db.py

@@ -1,6 +1,7 @@
 import nkms.db
 from nkms.db import DB
 import shutil
+import pytest
 
 # Monkey-patching for tests so that we don't overwrite the default db
 nkms.db.DB_NAME = 'debug-rekeys-db'
@@ -13,9 +14,16 @@ def test_db():
     db.close()
 
     db2 = DB()
+    assert b'x' in db2
     assert db2[b'x'] == b'y'
+    del db2[b'x']
     db2.close()
 
+    db = DB()
+    with pytest.raises(KeyError):
+        db[b'x']
+    assert b'x' not in db
+
     assert db.path == db2.path
 
     shutil.rmtree(db.path)