1 files changed, 79 insertions, 0 deletions
diff --git a/src/test_impl.rs b/src/test_impl.rs
new file mode 100644
index 0000000..c8f2b51
--- /dev/null
+++ b/src/test_impl.rs
@@ -0,0 +1,79 @@
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+//
+
+use std::sync::Arc;
+use std::sync::RwLock;
+
+use async_trait::async_trait;
+
+#[derive(Debug)]
+pub struct TestError;
+
+impl<Id> From<crate::Error<Id>> for TestError
+where
+    Id: crate::NodeId,
+{
+    fn from(_ce: crate::Error<Id>) -> Self {
+        TestError
+    }
+}
+
+#[derive(Copy, Clone, Eq, PartialEq, std::hash::Hash, Debug)]
+pub struct Id(pub(crate) usize);
+
+impl crate::NodeId for Id {}
+
+#[derive(Clone, Debug)]
+pub struct Node {
+    pub(crate) parents: Vec<Id>,
+    // data the node holds, used to create the ID in tests as "hashing" for unique id
+    pub(crate) data: usize,
+}
+
+impl crate::Node for Node {
+    type Id = Id;
+
+    fn parent_ids(&self) -> Vec<Self::Id> {
+        self.parents.clone()
+    }
+}
+
+/// The backend for the tests
+///
+/// This is `Clone` because we can test branching only with a clonable backend.
+/// A real backend would not implement the storage itself, but rather a way to retrieve the data
+/// from some storage mechansim (think IPFS), and thus `Clone`ing a backend is nothing esotheric.
+#[derive(Clone, Debug)]
+pub struct Backend(pub(crate) Arc<RwLock<Vec<Option<Node>>>>);
+
+impl Backend {
+    pub fn new(v: Vec<Option<Node>>) -> Self {
+        Backend(Arc::new(RwLock::new(v)))
+    }
+}
+
+#[async_trait]
+impl crate::DagBackend<Id, Node> for Backend {
+    type Error = TestError;
+
+    async fn get(&self, id: Id) -> Result<Option<(Id, Node)>, Self::Error> {
+        if self.0.read().unwrap().len() < id.0 + 1 {
+            Ok(None)
+        } else {
+            Ok(self.0.read().unwrap()[id.0].clone().map(|node| (id, node)))
+        }
+    }
+
+    async fn put(&mut self, node: Node) -> Result<Id, Self::Error> {
+        while self.0.read().unwrap().len() < node.data + 1 {
+            self.0.write().unwrap().push(None)
+        }
+
+        let idx = node.data;
+        self.0.write().unwrap()[idx] = Some(node);
+        Ok(Id(idx))
+    }
+}