From 6568bd0acc03f3df8b52a8429d7225dcd1a77f1f Mon Sep 17 00:00:00 2001
From: "K. R. Walker" <krwalker@stellarscience.com>
Date: Wed, 6 Sep 2023 14:42:45 -0600
Subject: [PATCH] Include negated assertion_result messages:

Given a helper function `isEqualCaseInsensitive()` returning helpful
detail in the resulting assertion_result message, negation of
that result in a `BOOST_CHECK()` results in that detail being
discarded.

This feature preserves that detail in the negated case.

For example:

`BOOST_CHECK(isEqualCaseInsensitive('z', 'Z'))` included detail like `[z
isEqualCaseInsensitiveTo Z]`

`BOOST_CHECK(!isEqualCaseInsensitive('z', 'Z'))` discarded that detail
until this revision, which now includes it: `NOT([z
isEqualCaseInsensitiveTo Z])`
---
 include/boost/test/tools/assertion_result.hpp | 13 +++++++-
 .../assertion-construction-test.cpp           | 31 +++++++++++++++++++
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/include/boost/test/tools/assertion_result.hpp b/include/boost/test/tools/assertion_result.hpp
index 85eea741f7..cd910fecec 100644
--- a/include/boost/test/tools/assertion_result.hpp
+++ b/include/boost/test/tools/assertion_result.hpp
@@ -57,7 +57,12 @@ class BOOST_TEST_DECL assertion_result {
     assertion_result( BoolConvertable const& pv_ ) : p_predicate_value( !!pv_ ) {}
 
     // Access methods
-    bool                operator!() const           { return !p_predicate_value; }
+    assertion_result    operator!() const
+    {
+        assertion_result negatedResult = !p_predicate_value;
+        negatedResult.message() << "NOT(" << ( !m_message ? std::string() : m_message->str() ) << ")";
+        return negatedResult;
+    }
     void                operator=( bool pv_ )       { p_predicate_value.value = pv_; }
     operator            safe_bool() const           { return !!p_predicate_value ? &dummy::nonnull : 0; }
 
@@ -75,6 +80,12 @@ class BOOST_TEST_DECL assertion_result {
     }
     const_string        message() const                   { return !m_message ? const_string() : const_string( m_message->str() ); }
 
+    // Operators
+    friend bool operator==(bool left, const assertion_result& right) { return left == static_cast<bool>(right); }
+    friend bool operator==(const assertion_result& left, bool right) { return static_cast<bool>(left) == right; }
+    friend bool operator!=(bool left, const assertion_result& right) { return left == static_cast<bool>(right); }
+    friend bool operator!=(const assertion_result& left, bool right) { return static_cast<bool>(left) == right; }
+
 private:
     // Data members
     shared_ptr<wrap_stringstream> m_message;
diff --git a/test/writing-test-ts/assertion-construction-test.cpp b/test/writing-test-ts/assertion-construction-test.cpp
index ad791aea91..7537905848 100644
--- a/test/writing-test-ts/assertion-construction-test.cpp
+++ b/test/writing-test-ts/assertion-construction-test.cpp
@@ -20,6 +20,7 @@
 
 #include <boost/noncopyable.hpp>
 
+#include <locale>
 #include <map>
 #include <set>
 
@@ -405,6 +406,15 @@ class NC : boost::noncopyable {
     }
 };
 
+boost::test_tools::predicate_result isEqualCaseInsensitive(char left, char right)
+{
+    boost::test_tools::predicate_result result(
+        std::tolower(left, std::locale::classic()) == std::tolower(right, std::locale::classic()));
+    result.message() << "[" << left << " isEqualCaseInsensitiveTo " << right << ']';
+    return result;
+}
+
+
 BOOST_AUTO_TEST_CASE( test_objects )
 {
     using namespace boost::test_tools;
@@ -469,6 +479,27 @@ BOOST_AUTO_TEST_CASE( test_objects )
         BOOST_TEST( !res );
         BOOST_TEST( res.message() == " [NC != NC]" );
     }
+
+    {
+        predicate_result const& res = EXPR_TYPE( isEqualCaseInsensitive('z', 'Z') ).evaluate();
+        BOOST_TEST( res );
+        BOOST_TEST( res.message() == "[z isEqualCaseInsensitiveTo Z]" );
+    }
+
+    {
+        predicate_result const& res = !EXPR_TYPE( isEqualCaseInsensitive('z', 'Z') ).evaluate();
+        BOOST_TEST( !res );
+        BOOST_TEST( res.message() == "NOT([z isEqualCaseInsensitiveTo Z])" );
+    }
+
+    {
+        NC nc1;
+        NC nc2;
+
+        predicate_result const& res = !EXPR_TYPE( nc1 == nc2 ).evaluate();
+        BOOST_TEST( res );
+        BOOST_TEST( res.message() == "NOT( [NC != NC])" );
+    }
 }
 
 //____________________________________________________________________________//