add common basic tests

tests/datastore/basictests.nim

@@ -0,0 +1,36 @@
+import std/options
+import std/os
+
+import pkg/asynctest
+import pkg/chronos
+import pkg/stew/results
+import pkg/stew/byteutils
+
+import pkg/datastore
+
+proc basicStoreTests*(
+  ds: Datastore,
+  key: Key,
+  bytes: seq[byte],
+  otherBytes: seq[byte]) =
+
+  test "put":
+    (await ds.put(key, bytes)).tryGet()
+
+  test "get":
+    check:
+      (await ds.get(key)).tryGet() == bytes
+
+  test "put update":
+    (await ds.put(key, otherBytes)).tryGet()
+
+  test "get updated":
+    check:
+      (await ds.get(key)).tryGet() == otherBytes
+
+  test "delete":
+    (await ds.delete(key)).tryGet()
+
+  test "contains":
+    check:
+      not (await ds.contains(key)).tryGet()