[query] Return Result<> from exec #47 (#48)

* Update transaction_test.rs

* Update db_test.rs

* Update transaction.rs

* Update db.rs

src/db.rs

@@ -1,11 +1,11 @@
-use crate::{Query, QueryResult, Transaction};
+use crate::{Query, QueryError, QueryResult, Transaction};
 
 #[derive(Default)]
 pub struct Db {}
 
 impl Db {
-    pub fn exec(&self, _query: Query) -> QueryResult {
-        QueryResult::default()
+    pub fn exec(&self, _query: Query) -> Result<QueryResult, QueryError> {
+        Ok(QueryResult::default())
     }
 
     pub fn transaction(&self) -> Transaction {

src/transaction.rs

@@ -8,8 +8,8 @@ impl Transaction {
         Ok(QueryResult::default())
     }
 
-    pub fn exec(&self, _query: Query) -> QueryResult {
-        QueryResult::default()
+    pub fn exec(&self, _query: Query) -> Result<QueryResult, QueryError> {
+        Ok(QueryResult::default())
     }
 
     pub fn transaction(&self) -> Transaction {

tests/db_test.rs

@@ -9,5 +9,5 @@ fn db_is_public_type() {
 fn exec_takes_query_returns_query_result() {
     let db = agdb::Db::default();
     let query = agdb::Query::default();
-    let _result: agdb::QueryResult = db.exec(query);
+    let _result: Result<agdb::QueryResult, agdb::QueryError> = db.exec(query);
 }

tests/transaction_test.rs

@@ -16,7 +16,7 @@ fn exec_takes_query_returns_query_result() {
     let db = agdb::Db::default();
     let query = agdb::Query::default();
     let transaction = db.transaction();
-    let _result: agdb::QueryResult = transaction.exec(query);
+    let _result: Result<agdb::QueryResult, agdb::QueryError> = transaction.exec(query);
 }
 
 #[test]