Add more property tests.

Use the test_strategy::proptest macro for nice async support.

Upstream proptest+tokio issue:
proptest-rs/proptest#179

While there is a workaround there, the `prop_assert!` macro didn't
seem to work properly. The `assert!` macro does work, but then we see
all the output when proptest tries to shrink a failing example.

Cargo.toml

@@ -28,4 +28,5 @@ debug = true
 [dev-dependencies]
 pretty_assertions = "1.4.0"
 proptest = "1.0.0"
+test-strategy = "0.4.0"
 tokio = { version = "1.39.2", features = ["rt-multi-thread", "macros"] }

src/dataset.rs

@@ -720,6 +720,27 @@ pub enum FlushError {
     StorageError(#[from] StorageError),
 }
 
+#[cfg(test)]
+mod strategies {
+    use std::path::PathBuf;
+    use std::sync::Arc;
+
+    use proptest::prelude::*;
+    use proptest::strategy::Strategy;
+
+    use crate::storage::InMemoryStorage;
+    use crate::{Dataset, Path};
+
+    pub(crate) fn node_path_strategy() -> impl Strategy<Value = Path> {
+        any::<PathBuf>()
+    }
+
+    pub(crate) fn dataset_strategy() -> impl Strategy<Value = Dataset> {
+        let storage = InMemoryStorage::new();
+        let dataset = Dataset::new(Arc::new(storage), None);
+        prop_oneof![Just(dataset)]
+    }
+}
 #[cfg(test)]
 mod tests {
     use std::{error::Error, num::NonZeroU64, path::PathBuf};
@@ -734,6 +755,28 @@ mod tests {
     use super::*;
     use itertools::Itertools;
     use pretty_assertions::assert_eq;
+    use proptest::prelude::{prop_assert, prop_assert_eq};
+    use strategies::*;
+    use test_strategy::proptest;
+
+    #[proptest(async = "tokio")]
+    async fn test_add_delete_group(
+        #[strategy(node_path_strategy())] path: Path,
+        #[strategy(dataset_strategy())] mut dataset: Dataset,
+    ) {
+        prop_assert!(dataset.get_node(&path).await.is_err());
+
+        dataset.add_group(path.clone()).await.unwrap();
+        let node = dataset.get_node(&path).await;
+        prop_assert!(node.is_ok());
+        prop_assert_eq!(node.unwrap(), dataset.get_node(&path).await.unwrap());
+
+        // adding an existing group fails
+        prop_assert!(dataset.add_group(path.clone()).await.is_err());
+
+        dataset.delete_group(path.clone()).await.unwrap();
+        prop_assert!(dataset.get_node(&path).await.is_err());
+    }
 
     #[tokio::test(flavor = "multi_thread")]
     async fn test_dataset_with_updates() -> Result<(), Box<dyn Error>> {

src/lib.rs

@@ -765,7 +765,14 @@ pub trait Storage {
     async fn write_chunk(&self, id: ObjectId, bytes: Bytes) -> Result<(), StorageError>;
 }
 
-#[derive(Clone)]
+impl fmt::Debug for dyn Storage + Send + Sync {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        // FIXME
+        write!(f, "Storage")
+    }
+}
+
+#[derive(Clone, Debug)]
 pub struct Dataset {
     storage: Arc<dyn Storage + Send + Sync>,
     structure_id: Option<ObjectId>,