Make NaN test more comprehensive

Author: sfackler

src/postgres/test.rs

@@ -312,6 +312,11 @@ fn test_tm_params() {
 
 fn test_nan_param<T: Float+ToSql+FromSql>(sql_type: &str) {
     let conn = PostgresConnection::connect("postgres://postgres@localhost");
+    let stmt = conn.prepare("SELECT 'NaN'::" + sql_type);
+    let mut result = stmt.query([]);
+    let val: T = result.next().unwrap()[0];
+    assert!(val.is_nan());
+
     let nan: T = Float::nan();
     let stmt = conn.prepare("SELECT $1::" + sql_type);
     let mut result = stmt.query([&nan as &ToSql]);