Add failing test case.

Author: ggreer

pkg/database/database_test.go

@@ -105,6 +105,14 @@ func Test_expandDSN(t *testing.T) {
 			dsn:  "mysql://admin:${DB_PASSWORD}@localhost:3306/dbname",
 			want: "mysql://admin:p%40ss%23123@localhost:3306/dbname",
 		},
+		{
+			name: "Port",
+			env: map[string]string{
+				"DB_PORT": "3306",
+			},
+			dsn:  "mysql://user:password@localhost:${DB_PORT}/dbname",
+			want: "mysql://user:password@localhost:3306/dbname",
+		},
 		{
 			name: "Password with multiple special characters",
 			env: map[string]string{