Implement MigrationConnection for the AsyncConnectionWrapper type

This allows to execute migrations. Also add a simple test for that.

Author: weiznich

Cargo.toml

@@ -32,6 +32,7 @@ tokio = {version = "1.12.0", features = ["rt", "macros", "rt-multi-thread"]}
 cfg-if = "1"
 chrono = "0.4"
 diesel = { version = "2.1.0", default-features = false,  features = ["chrono"]}
+diesel_migrations = "2.1.0"
 
 [features]
 default = []

src/async_connection_wrapper.rs

@@ -100,6 +100,8 @@ pub type AsyncConnectionWrapper<C, B = self::implementation::Tokio> =
 pub use self::implementation::AsyncConnectionWrapper;
 
 mod implementation {
+    use diesel::connection::SimpleConnection;
+
     use super::*;
 
     pub struct AsyncConnectionWrapper<C, B> {
@@ -271,6 +273,17 @@ mod implementation {
         }
     }
 
+    impl<C, B> diesel::migration::MigrationConnection for AsyncConnectionWrapper<C, B>
+    where
+        B: BlockOn,
+        Self: diesel::Connection,
+    {
+        fn setup(&mut self) -> diesel::QueryResult<usize> {
+            self.batch_execute(diesel::migration::CREATE_MIGRATIONS_TABLE)
+                .map(|()| 0)
+        }
+    }
+
     #[cfg(feature = "tokio")]
     pub struct Tokio {
         handle: Option<tokio::runtime::Handle>,

tests/lib.rs

@@ -92,6 +92,9 @@ type TestConnection = AsyncMysqlConnection;
 #[cfg(feature = "postgres")]
 type TestConnection = AsyncPgConnection;
 
+#[allow(dead_code)]
+type TestBackend = <TestConnection as AsyncConnection>::Backend;
+
 #[tokio::test]
 async fn test_basic_insert_and_load() -> QueryResult<()> {
     let conn = &mut connection().await;

tests/sync_wrapper.rs

@@ -1,3 +1,4 @@
+use diesel::migration::Migration;
 use diesel::prelude::*;
 use diesel_async::async_connection_wrapper::AsyncConnectionWrapper;
 
@@ -24,3 +25,15 @@ async fn test_sync_wrapper_under_runtime() {
     .await
     .unwrap();
 }
+
+#[test]
+fn check_run_migration() {
+    use diesel_migrations::MigrationHarness;
+
+    let db_url = std::env::var("DATABASE_URL").unwrap();
+    let migrations: Vec<Box<dyn Migration<crate::TestBackend>>> = Vec::new();
+    let mut conn = AsyncConnectionWrapper::<crate::TestConnection>::establish(&db_url).unwrap();
+
+    // just use `run_migrations` here because that's the easiest one without additional setup
+    conn.run_migrations(&migrations).unwrap();
+}