test: added tests for M2M relationships, it works

tests/o2m_relationship.rs

@@ -0,0 +1,33 @@
+use georm::Georm;
+
+mod models;
+use models::*;
+
+#[sqlx::test(fixtures("simple_struct", "o2o"))]
+async fn books_access_one_review(pool: sqlx::PgPool) -> sqlx::Result<()> {
+    let book = Book::find(&pool, &1).await?.unwrap();
+    let reviews = book.get_reviews(&pool).await?;
+    let review = Review {
+        id: 1,
+        book_id: 1,
+        review: "Great book".into(),
+    };
+    assert_eq!(vec![review], reviews);
+    Ok(())
+}
+
+#[sqlx::test(fixtures("simple_struct", "o2o"))]
+async fn books_should_access_their_multiple_reviews(pool: sqlx::PgPool) -> sqlx::Result<()> {
+    let book = Book::find(&pool, &2).await?.unwrap();
+    let reviews = book.get_reviews(&pool).await?;
+    assert_eq!(2, reviews.len());
+    Ok(())
+}
+
+#[sqlx::test(fixtures("simple_struct", "o2o"))]
+async fn books_can_have_no_reviews(pool: sqlx::PgPool) -> sqlx::Result<()> {
+    let book = Book::find(&pool, &4).await?.unwrap();
+    let reviews = book.get_reviews(&pool).await?;
+    assert_eq!(0, reviews.len());
+    Ok(())
+}