Add CREATE TABLE test for created instance

Author: mbr

src/postgres.rs

@@ -203,5 +203,12 @@ mod tests {
         con.create_instance("myrole", "mypw", "mydb")
             .await
             .expect("failed to create instance");
+
+        // Now that the instance is created, check every is in working order.
+        let user_con = pg.as_user("myrole", "mypw");
+        user_con
+            .run_sql("mydb", "CREATE TABLE foo (bar INT PRIMARY KEY);")
+            // .run_sql("mydb", "SELECT current_database();")
+            .expect("could not run query");
     }
 }