narrow: Also check if a value has changed sign after cast.

Fixes https://github.com/Microsoft/GSL/issues/222.

1 files changed, 29 insertions, 16 deletions

diff --git a/tests/utils_tests.cpp b/tests/utils_tests.cpp
index 9406e6b..a46d6e4 100644
--- a/tests/utils_tests.cpp
+++ b/tests/utils_tests.cpp
@@ -1,20 +1,20 @@
-/////////////////////////////////////////////////////////////////////////////// 
-// 
-// Copyright (c) 2015 Microsoft Corporation. All rights reserved. 
-// 
-// This code is licensed under the MIT License (MIT). 
-// 
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 
-// THE SOFTWARE. 
-// 
+///////////////////////////////////////////////////////////////////////////////
+//
+// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
+//
+// This code is licensed under the MIT License (MIT).
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+//
 ///////////////////////////////////////////////////////////////////////////////
 
-#include <UnitTest++/UnitTest++.h> 
+#include <UnitTest++/UnitTest++.h>
 #include <gsl.h>
 #include <functional>
 
@@ -95,8 +95,21 @@ SUITE(utils_tests)
         char c = narrow<char>(n);
         CHECK(c == 120);
 
-        n = 300;        
+        n = 300;
         CHECK_THROW(narrow<char>(n), narrowing_error);
+
+        const auto int32_max = std::numeric_limits<int32_t>::max();
+        const auto int32_min = std::numeric_limits<int32_t>::min();
+
+        CHECK(narrow<uint32_t>(int32_t(0)) == 0);
+        CHECK(narrow<uint32_t>(int32_t(1)) == 1);
+        CHECK(narrow<uint32_t>(int32_max) == int32_max);
+
+        CHECK_THROW(narrow<uint32_t>(int32_t(-1)), narrowing_error);
+        CHECK_THROW(narrow<uint32_t>(int32_min), narrowing_error);
+
+        n = -42;
+        CHECK_THROW(narrow<unsigned>(n), narrowing_error);
     }
 }