erlang: fib_server.erl, 5/5 classic programs (+8 tests)

lib/erlang/tests/programs/fib_server.sx

@@ -0,0 +1,152 @@
+;; Fib server — long-lived process that computes fibonacci numbers on
+;; request. Tests recursive function evaluation inside a server loop.
+
+(define er-fib-test-count 0)
+(define er-fib-test-pass 0)
+(define er-fib-test-fails (list))
+
+(define
+  er-fib-test
+  (fn
+    (name actual expected)
+    (set! er-fib-test-count (+ er-fib-test-count 1))
+    (if
+      (= actual expected)
+      (set! er-fib-test-pass (+ er-fib-test-pass 1))
+      (append! er-fib-test-fails {:actual actual :expected expected :name name}))))
+
+(define fib-ev erlang-eval-ast)
+
+;; Fib + server-loop source. Standalone so each test can chain queries.
+(define
+  er-fib-server-src
+  "Fib = fun (0) -> 0; (1) -> 1; (N) -> Fib(N-1) + Fib(N-2) end,
+   FibSrv = fun () ->
+     Loop = fun () ->
+       receive
+         {fib, N, From} -> From ! Fib(N), Loop();
+         stop -> ok
+       end
+     end,
+     Loop()
+   end")
+
+;; Base cases.
+(er-fib-test
+  "fib(0)"
+  (fib-ev
+    (str
+      er-fib-server-src
+      ", Me = self(),
+       Srv = spawn(FibSrv),
+       Srv ! {fib, 0, Me},
+       receive R -> Srv ! stop, R end"))
+  0)
+
+(er-fib-test
+  "fib(1)"
+  (fib-ev
+    (str
+      er-fib-server-src
+      ", Me = self(),
+       Srv = spawn(FibSrv),
+       Srv ! {fib, 1, Me},
+       receive R -> Srv ! stop, R end"))
+  1)
+
+;; Larger values.
+(er-fib-test
+  "fib(10) = 55"
+  (fib-ev
+    (str
+      er-fib-server-src
+      ", Me = self(),
+       Srv = spawn(FibSrv),
+       Srv ! {fib, 10, Me},
+       receive R -> Srv ! stop, R end"))
+  55)
+
+(er-fib-test
+  "fib(15) = 610"
+  (fib-ev
+    (str
+      er-fib-server-src
+      ", Me = self(),
+       Srv = spawn(FibSrv),
+       Srv ! {fib, 15, Me},
+       receive R -> Srv ! stop, R end"))
+  610)
+
+;; Multiple sequential queries to one server. Sum to avoid dict-equality.
+(er-fib-test
+  "sequential fib(5..8) sum"
+  (fib-ev
+    (str
+      er-fib-server-src
+      ", Me = self(),
+       Srv = spawn(FibSrv),
+       Srv ! {fib, 5, Me}, A = receive Ra -> Ra end,
+       Srv ! {fib, 6, Me}, B = receive Rb -> Rb end,
+       Srv ! {fib, 7, Me}, C = receive Rc -> Rc end,
+       Srv ! {fib, 8, Me}, D = receive Rd -> Rd end,
+       Srv ! stop,
+       A + B + C + D"))
+  47)
+
+;; Verify Fib obeys the recurrence — fib(n) = fib(n-1) + fib(n-2).
+(er-fib-test
+  "fib recurrence at n=12"
+  (fib-ev
+    (str
+      er-fib-server-src
+      ", Me = self(),
+       Srv = spawn(FibSrv),
+       Srv ! {fib, 10, Me}, A = receive Ra -> Ra end,
+       Srv ! {fib, 11, Me}, B = receive Rb -> Rb end,
+       Srv ! {fib, 12, Me}, C = receive Rc -> Rc end,
+       Srv ! stop,
+       C - (A + B)"))
+  0)
+
+;; Two clients each get their own answer; main sums the results.
+(er-fib-test
+  "two clients sum"
+  (fib-ev
+    (str
+      er-fib-server-src
+      ", Me = self(),
+       Srv = spawn(FibSrv),
+       Client = fun (N) ->
+         spawn(fun () ->
+           Srv ! {fib, N, self()},
+           receive R -> Me ! {result, R} end
+         end)
+       end,
+       Client(7),
+       Client(9),
+       {result, A} = receive M1 -> M1 end,
+       {result, B} = receive M2 -> M2 end,
+       Srv ! stop,
+       A + B"))
+  47)
+
+;; Trace queries via io-buffer.
+(er-fib-test
+  "trace fib 0..6"
+  (do
+    (er-io-flush!)
+    (fib-ev
+      (str
+        er-fib-server-src
+        ", Me = self(),
+         Srv = spawn(FibSrv),
+         Ask = fun (N) -> Srv ! {fib, N, Me}, receive R -> io:format(\"~p \", [R]) end end,
+         Ask(0), Ask(1), Ask(2), Ask(3), Ask(4), Ask(5), Ask(6),
+         Srv ! stop,
+         done"))
+    (er-io-buffer-content))
+  "0 1 1 2 3 5 8 ")
+
+(define
+  er-fib-test-summary
+  (str "fib " er-fib-test-pass "/" er-fib-test-count))