diff --git a/src/ast/dml/select.rs b/src/ast/dml/select.rs
index b6a159c..c2847e6 100644
--- a/src/ast/dml/select.rs
+++ b/src/ast/dml/select.rs
@@ -226,3 +226,65 @@ impl From<SelectQuery> for SQLExpression {
         SQLExpression::Subquery(SubqueryExpression::Select(Box::new(value)))
     }
 }
+
+#[cfg(test)]
+#[allow(non_snake_case)]
+mod tests {
+    use crate::ast::{
+        dml::expressions::call::CallExpression,
+        types::{AggregateFunction, BuiltInFunction, Function},
+    };
+
+    use super::*;
+
+    #[test]
+    fn test_from_table() {
+        let select_query = SelectQuery::builder()
+            .set_from_table(TableName::new(None, "table".into()))
+            .build();
+
+        assert!(select_query.has_from_table());
+    }
+
+    #[test]
+    fn test_has_group_by() {
+        let select_query = SelectQuery::builder().build();
+
+        assert_eq!(select_query.has_group_by(), false);
+
+        let select_query = SelectQuery::builder()
+            .add_group_by(GroupByItem {
+                item: SelectColumn {
+                    table_name: None,
+                    column_name: "foo".into(),
+                },
+            })
+            .build();
+
+        assert_eq!(select_query.has_group_by(), true);
+    }
+
+    #[test]
+    fn test_get_aggregate_column() {
+        let select_query = SelectQuery::builder()
+            .add_select_item(
+                SelectItem::builder()
+                    .set_item(SQLExpression::FunctionCall(CallExpression {
+                        function: Function::BuiltIn(BuiltInFunction::Aggregate(
+                            AggregateFunction::Count,
+                        )),
+                        arguments: vec![SQLExpression::SelectColumn(SelectColumn {
+                            table_name: None,
+                            column_name: "bar".into(),
+                        })],
+                    }))
+                    .build(),
+            )
+            .build();
+
+        let aggregate_columns = select_query.get_aggregate_column();
+
+        assert_eq!(aggregate_columns.len(), 1);
+        assert_eq!(aggregate_columns[0].column_name, "bar");
+    }
+}