Fix the sense of the cfg(feature = "lua-no-oslib") test.

Add tests.

Author: jugglerchris

src/lua.rs

@@ -782,7 +782,7 @@ unsafe fn load_from_std_lib(state: *mut ffi::lua_State, lua_mod: StdLib) {
     if lua_mod.contains(StdLib::IO) {
         requiref(state, cstr!("io"), Some(ffi::luaopen_io), 1);
     }
-    #[cfg(feature = "lua-no-oslib")]
+    #[cfg(not(feature = "lua-no-oslib"))]
     if lua_mod.contains(StdLib::OS) {
         requiref(state, cstr!("os"), Some(ffi::luaopen_os), 1);
     }

tests/tests.rs

@@ -1437,3 +1437,38 @@ fn context_thread_lua51() {
         thrd.resume::<_, ()>(thrd_cloned).unwrap();
     });
 }
+
+// Test the lua-no-oslib feature
+#[cfg(feature = "lua-no-oslib")]
+#[test]
+fn test_no_oslib() {
+    Lua::new().context(|lua_ctx| {
+        let f = lua_ctx
+            .load(
+                r#"
+                    assert(os == nil)
+                "#,
+            )
+            .into_function()
+            .unwrap();
+        f.call::<_, ()>(()).unwrap();
+    });
+}
+
+// Test the lua-no-oslib feature
+#[cfg(not(feature = "lua-no-oslib"))]
+#[test]
+fn test_with_oslib() {
+    Lua::new().context(|lua_ctx| {
+        let f = lua_ctx
+            .load(
+                r#"
+                    local x = os.time()
+                    assert(x > 0)
+                "#,
+            )
+            .into_function()
+            .unwrap();
+        f.call::<_, ()>(()).unwrap();
+    });
+}