feat(parser-tests): add fibonacci parser test

lib/tests/parser/dune

@@ -1,6 +1,6 @@
 (library
  (name tests)
- (modules parse_simple_expr parse_factorial)
+ (modules parse_simple_expr parse_factorial parse_fibonacci)
  (libraries parser ast)
  (preprocess
   (pps ppx_expect ppx_deriving.show))

lib/tests/parser/parse_fibonacci.ml

@@ -0,0 +1,35 @@
+(* * Copyright 2024, raf-nr and ksenmel *)
+
+(** SPDX-License-Identifier: LGPL-3.0-or-later *)
+
+open Base
+open Parser
+
+let%expect_test _ =
+  test_parse "let rec fib n = if n > 1 then fib (n - 1) + fib (n - 2) else 1";
+  [%expect {|
+    [(SDeclaration
+        (DRecursive
+           ((PVar (Id "fib")),
+            (EFun (((PVar (Id "n")), []),
+               (EIfThenElse (
+                  (EApplication ((EIdentifier (Id "( > )")),
+                     [(EIdentifier (Id "n")); (EConstant (CInt 1))])),
+                  (EApplication ((EIdentifier (Id "fib")),
+                     [(EApplication ((EIdentifier (Id "n")),
+                         [(EApplication ((EIdentifier (Id "( - )")),
+                             [(EConstant (CInt 0)); (EConstant (CInt 1))]))
+                           ]
+                         ));
+                       (EApplication ((EIdentifier (Id "( + )")),
+                          [(EConstant (CInt 0)); (EIdentifier (Id "fib"))]));
+                       (EApplication ((EIdentifier (Id "n")),
+                          [(EApplication ((EIdentifier (Id "( - )")),
+                              [(EConstant (CInt 0)); (EConstant (CInt 2))]))
+                            ]
+                          ))
+                       ]
+                     )),
+                  (Some (EConstant (CInt 1)))))
+               )))))
+      ] |}]