[lmi-commits] [lmi] master b9b9b0f 2/4: Improve unit tests for boost::numeric_cast

[Greg Chicares]

branch: master
commit b9b9b0f4b7a78054a729611a8c725af9c8484270
Author: Gregory W. Chicares <address@hidden>
Commit: Gregory W. Chicares <address@hidden>

    Improve unit tests for boost::numeric_cast
    
    Tests that formerly verified the actual (but incorrect) behavior have
    been replaced by tests that fail for incorrect behavior.
---
 bourn_cast_test.cpp | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/bourn_cast_test.cpp b/bourn_cast_test.cpp
index b85b227..23d0ff3 100644
--- a/bourn_cast_test.cpp
+++ b/bourn_cast_test.cpp
@@ -248,9 +248,11 @@ void test_floating_conversions(char const* file, int line)
     INVOKE_BOOST_TEST_EQUAL( to_inf, bourn_cast<To>( from_inf), file, line);
     INVOKE_BOOST_TEST_EQUAL(-to_inf, bourn_cast<To>(-from_inf), file, line);
 #else  // defined TEST_BOOST_CAST_INSTEAD
-    // Boost doesn't allow conversion of infinities to a narrower
-    // floating type, presumably because is presumptively permits
-    // conversion to the same or a wider floating type.
+    // Boost allows conversion of infinities to the same type or a
+    // wider floating type, but not to a narrower type--presumably
+    // because infinities are outside the [lowest(), max()] range but
+    // non-narrowing conversions are presumptively allowed regardless
+    // of value.
     if(from_traits::digits10 <= to_traits::digits10) // Widening or same.
         {
         INVOKE_BOOST_TEST_EQUAL( to_inf, bourn_cast<To>( from_inf), file, 
line);
@@ -258,16 +260,15 @@ void test_floating_conversions(char const* file, int line)
         }
     else
         {
-        INVOKE_BOOST_TEST(false, file, line); // This should be allowed.
         BOOST_TEST_THROW
             (bourn_cast<To>( from_traits::infinity())
             ,std::runtime_error
-            ,"Cast would transgress upper limit."
+            ,"This cast should have succeeded."
             );
         BOOST_TEST_THROW
             (bourn_cast<To>(-from_traits::infinity())
             ,std::runtime_error
-            ,"Cast would transgress lower limit."
+            ,"This cast should have succeeded."
             );
         }
 #endif // defined TEST_BOOST_CAST_INSTEAD