Add 'unnecessary_flat_map.fixed'

Author: jeremystucki

tests/ui/unnecessary_flat_map.fixed

@@ -0,0 +1,13 @@
+// run-rustfix
+
+#![warn(clippy::flat_map_identity)]
+
+use std::convert;
+
+fn main() {
+    let iterator = [[0, 1], [2, 3], [4, 5]].iter();
+    iterator.flatten();
+
+    let iterator = [[0, 1], [2, 3], [4, 5]].iter();
+    iterator.flatten();
+}