database: add open table tests

Cargo.lock

@@ -559,6 +559,32 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "cuprate-database"
+version = "0.0.1"
+dependencies = [
+ "bitflags 2.5.0",
+ "bytemuck",
+ "bytes",
+ "cfg-if",
+ "cuprate-helper",
+ "cuprate-test-utils",
+ "cuprate-types",
+ "curve25519-dalek",
+ "heed",
+ "hex",
+ "hex-literal",
+ "monero-pruning",
+ "monero-serai",
+ "page_size",
+ "paste",
+ "pretty_assertions",
+ "redb",
+ "serde",
+ "tempfile",
+ "thiserror",
+]
+
 [[package]]
 name = "cuprate-fast-sync"
 version = "0.1.0"
@@ -733,32 +759,6 @@ dependencies = [
  "parking_lot_core",
 ]
 
-[[package]]
-name = "database"
-version = "0.0.0"
-dependencies = [
- "bitflags 2.5.0",
- "bytemuck",
- "bytes",
- "cfg-if",
- "cuprate-helper",
- "cuprate-test-utils",
- "cuprate-types",
- "curve25519-dalek",
- "heed",
- "hex",
- "hex-literal",
- "monero-pruning",
- "monero-serai",
- "page_size",
- "paste",
- "pretty_assertions",
- "redb",
- "serde",
- "tempfile",
- "thiserror",
-]
-
 [[package]]
 name = "diff"
 version = "0.1.13"

storage/database/README.md

@@ -32,6 +32,17 @@ Which reads as:
 1. You open a particular `Table` from that `Environment`, getting a `Database`
 1. You can now read/write data from/to that `Database`
 
+# Concrete types
+You should _not_ rely on the concrete type of any abstracted backend.
+
+For example, when using the `heed` backend, [`Env`]'s associated [`TxRw`] type
+is `RefCell<heed::RwTxn<'_>>`. In order to ensure compatibility with other backends
+and to not create backend-specific code, you should _not_ refer to that concrete type.
+
+Use generics and trait notation in these situations:
+- `impl<T: TxRw> Trait for Object`
+- `fn() -> impl TxRw`
+
 # `ConcreteEnv`
 This crate exposes [`ConcreteEnv`], which is a non-generic/non-dynamic,
 concrete object representing a database [`Env`]ironment.
@@ -108,7 +119,8 @@ impl cuprate_database::Table for Table {
 // Open up a transaction + tables for writing.
 let env_inner = env.env_inner();
 let tx_rw = env_inner.tx_rw()?;
-env_inner.create_db::<Table>(&tx_rw)?; // we must create it or the next line will panic.
+// We must create the table first or the next line will error.
+env_inner.create_db::<Table>(&tx_rw)?;
 let mut table = env_inner.open_db_rw::<Table>(&tx_rw)?;
 
 // Write data to the table.

storage/database/src/backend/tests.rs

@@ -71,7 +71,7 @@ fn open_db() {
 
 /// Assert that opening a read-only table before creating errors.
 #[test]
-fn open_uncreated_table() {
+fn open_ro_uncreated_table() {
     let (env, _tempdir) = tmp_concrete_env();
     let env_inner = env.env_inner();
     let tx_ro = env_inner.tx_ro().unwrap();
@@ -81,6 +81,42 @@ fn open_uncreated_table() {
     assert!(matches!(error, Err(RuntimeError::TableNotFound)));
 }
 
+/// Assert that opening a read/write table before creating is OK.
+#[test]
+fn open_rw_uncreated_table() {
+    let (env, _tempdir) = tmp_concrete_env();
+    let env_inner = env.env_inner();
+    let tx_rw = env_inner.tx_rw().unwrap();
+
+    // Open uncreated table.
+    let _table = env_inner.open_db_rw::<TestTable>(&tx_rw).unwrap();
+}
+
+/// Assert that opening a read-only table after creating is OK.
+#[test]
+fn open_ro_created_table() {
+    let (env, _tempdir) = tmp_concrete_env();
+    let env_inner = env.env_inner();
+
+    // Assert uncreated table errors.
+    {
+        let tx_ro = env_inner.tx_ro().unwrap();
+        let error = env_inner.open_db_ro::<TestTable>(&tx_ro);
+        assert!(matches!(error, Err(RuntimeError::TableNotFound)));
+    }
+
+    // Create table.
+    {
+        let tx_rw = env_inner.tx_rw().unwrap();
+        env_inner.create_db::<TestTable>(&tx_rw).unwrap();
+        TxRw::commit(tx_rw).unwrap();
+    }
+
+    // Assert created table is now OK.
+    let tx_ro = env_inner.tx_ro().unwrap();
+    let _table = env_inner.open_db_ro::<TestTable>(&tx_ro).unwrap();
+}
+
 /// Test `Env` resizes.
 #[test]
 fn resize() {