Fix close() return type and dlclose error check; add tests

dynlib.carp

@@ -62,10 +62,10 @@ a shared library `lib`. Returns a `Result` with the function on success, or the
           f (dlsym lib (cstr &fqn))]
       (if (valid? f) (Result.Success @f) (Result.Error (dlerror)))))
 
-  (doc close "closes a library `lib`. Either returns nothing or, if an error
-occurs, it returns the error message.")
+  (doc close "closes a library `lib`. Returns a `Result` with `()` on success,
+or the `dlerror` message on failure.")
   (defn close [lib]
-    (if (= -1 (dlclose lib)) (Maybe.Just (dlerror)) (Maybe.Nothing)))
+    (if (/= 0 (dlclose lib)) (Result.Error (dlerror)) (Result.Success ())))
 
   (defmacro rebind [lib s]
     (list 'match

test/dynlib.carp

@@ -0,0 +1,56 @@
+(load "../dynlib.carp")
+(load "Test.carp")
+(use Test)
+
+(defn main []
+  (with-test test
+    ; open succeeds for a real library
+    (assert-true test
+      (Result.success? &(DynLib.open "libm.so.6"))
+      "open succeeds for libm")
+
+    ; open fails for a nonexistent library
+    (assert-true test
+      (Result.error? &(DynLib.open "libnonexistent.so"))
+      "open fails for nonexistent library")
+
+    ; get succeeds for a known symbol
+    (match (DynLib.open "libm.so.6")
+      (Result.Success lib)
+        (let-do [result (the (Result (Fn [Double] Double) String)
+                             (DynLib.get lib "floor"))
+                 ok (Result.success? &result)]
+          (ignore result)
+          (ignore (DynLib.close lib))
+          (assert-true test ok "get succeeds for known symbol"))
+      (Result.Error _) (assert-true test false "get succeeds for known symbol"))
+
+    ; get fails for a nonexistent symbol
+    (match (DynLib.open "libm.so.6")
+      (Result.Success lib)
+        (let-do [result (the (Result (Fn [] ()) String)
+                             (DynLib.get lib "nonexistent_symbol_xyz"))
+                 bad (Result.error? &result)]
+          (ignore result)
+          (ignore (DynLib.close lib))
+          (assert-true test bad "get fails for nonexistent symbol"))
+      (Result.Error _)
+        (assert-true test false "get fails for nonexistent symbol"))
+
+    ; close succeeds on a valid handle
+    (match (DynLib.open "libm.so.6")
+      (Result.Success lib)
+        (assert-true test
+          (Result.success? &(DynLib.close lib))
+          "close succeeds on valid handle")
+      (Result.Error _) (assert-true test false "close succeeds on valid handle"))
+
+    ; close returns Result.Success () on success
+    (match (DynLib.open "libm.so.6")
+      (Result.Success lib)
+        (assert-equal test
+          &(Result.Success ())
+          &(DynLib.close lib)
+          "close returns Result.Success on success")
+      (Result.Error _)
+        (assert-true test false "close returns Result.Success on success"))))