From 6e3692391560ce130ba3997db7158d3d64c12a43 Mon Sep 17 00:00:00 2001
From: Bjorn Reese <breese@users.sourceforge.net>
Date: Sat, 6 Jun 2020 18:52:43 +0200
Subject: [PATCH] Added BOOST_TEST_WITH macro to verify test results with
 custom predicate

---
 include/boost/core/lightweight_test.hpp | 72 ++++++++++++++++++++-----
 test/Jamfile.v2                         |  2 +
 test/lightweight_test_with_test.cpp     | 41 ++++++++++++++
 3 files changed, 101 insertions(+), 14 deletions(-)
 create mode 100644 test/lightweight_test_with_test.cpp

diff --git a/include/boost/core/lightweight_test.hpp b/include/boost/core/lightweight_test.hpp
index 43507ad..405682c 100644
--- a/include/boost/core/lightweight_test.hpp
+++ b/include/boost/core/lightweight_test.hpp
@@ -173,42 +173,84 @@ template<class T> inline const void* test_output_impl(T volatile* v) { return co
 inline const void* test_output_impl(std::nullptr_t) { return nullptr; }
 #endif
 
-struct lw_test_eq {
+template <typename BinaryPredicate>
+struct lw_name_traits
+{
+    static const char* op() { return "<+>"; }
+};
+
+struct lw_test_eq
+{
     template <typename T, typename U>
     bool operator()(const T& t, const U& u) const { return t == u; }
+};
+
+template <>
+struct lw_name_traits<lw_test_eq>
+{
     static const char* op() { return "=="; }
 };
-
-struct lw_test_ne {
+    
+struct lw_test_ne
+{
     template <typename T, typename U>
     bool operator()(const T& t, const U& u) const { return t != u; }
+};
+
+template <>
+struct lw_name_traits<lw_test_ne>
+{
     static const char* op() { return "!="; }
 };
-
-struct lw_test_lt {
+    
+struct lw_test_lt
+{
     template <typename T, typename U>
     bool operator()(const T& t, const U& u) const { return t < u; }
+};
+
+template <>
+struct lw_name_traits<lw_test_lt>
+{
     static const char* op() { return "<"; }
 };
-
-struct lw_test_le {
+    
+struct lw_test_le
+{
     template <typename T, typename U>
     bool operator()(const T& t, const U& u) const { return t <= u; }
+};
+
+template <>
+struct lw_name_traits<lw_test_le>
+{
     static const char* op() { return "<="; }
 };
-
-struct lw_test_gt {
+    
+struct lw_test_gt
+{
     template <typename T, typename U>
     bool operator()(const T& t, const U& u) const { return t > u; }
+};
+
+template <>
+struct lw_name_traits<lw_test_gt>
+{
     static const char* op() { return ">"; }
 };
-
-struct lw_test_ge {
+    
+struct lw_test_ge
+{
     template <typename T, typename U>
     bool operator()(const T& t, const U& u) const { return t >= u; }
-    static const char* op() { return ">="; }
 };
 
+template <>
+struct lw_name_traits<lw_test_ge>
+{
+    static const char* op() { return ">="; }
+};
+    
 template<class BinaryPredicate, class T, class U>
 inline bool test_with_impl(BinaryPredicate pred, char const * expr1, char const * expr2,
                            char const * file, int line, char const * function,
@@ -222,8 +264,8 @@ inline bool test_with_impl(BinaryPredicate pred, char const * expr1, char const
     else
     {
         BOOST_LIGHTWEIGHT_TEST_OSTREAM
-            << file << "(" << line << "): test '" << expr1 << " " << pred.op() << " " << expr2
-            << "' ('" << test_output_impl(t) << "' " << pred.op() << " '" << test_output_impl(u)
+            << file << "(" << line << "): test '" << expr1 << " " << lw_name_traits<decltype(pred)>::op() << " " << expr2
+            << "' ('" << test_output_impl(t) << "' " << lw_name_traits<decltype(pred)>::op() << " '" << test_output_impl(u)
             << "') failed in function '" << function << "'" << std::endl;
         ++test_results().errors();
         return false;
@@ -448,6 +490,8 @@ inline int report_errors()
 
 #define BOOST_ERROR(msg) ( ::boost::detail::error_impl(msg, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION) )
 
+#define BOOST_TEST_WITH(expr1,expr2,predicate) ( ::boost::detail::test_with_impl(predicate, #expr1, #expr2, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION, expr1, expr2) )
+
 #define BOOST_TEST_EQ(expr1,expr2) ( ::boost::detail::test_with_impl(::boost::detail::lw_test_eq(), #expr1, #expr2, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION, expr1, expr2) )
 #define BOOST_TEST_NE(expr1,expr2) ( ::boost::detail::test_with_impl(::boost::detail::lw_test_ne(), #expr1, #expr2, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION, expr1, expr2) )
 
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index d565ceb..f39218a 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -79,6 +79,8 @@ run lightweight_test_test.cpp : : :
   <exception-handling>off $(pedantic-errors) : lightweight_test_test_no_except ;
 run lightweight_test_test2.cpp
   : : : $(pedantic-errors) ;
+run lightweight_test_with_test.cpp
+  : : : $(pedantic-errors) ;
 run lightweight_test_all_with_test.cpp
   : : : $(pedantic-errors) ;
 run lightweight_test_lt_le_test.cpp
diff --git a/test/lightweight_test_with_test.cpp b/test/lightweight_test_with_test.cpp
new file mode 100644
index 0000000..9f3c42b
--- /dev/null
+++ b/test/lightweight_test_with_test.cpp
@@ -0,0 +1,41 @@
+//
+// Test for BOOST_TEST_WITH
+//
+// Copyright (c) 2020 Bjorn Reese
+//
+// Distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+//
+
+#include <cmath>
+#include <functional>
+#include <vector>
+#include <boost/core/lightweight_test.hpp>
+
+template <typename T>
+struct with_tolerance
+{
+    with_tolerance(T tolerance) : tolerance(tolerance) {}
+    bool operator()(T lhs, T rhs)
+    {
+        return (std::abs(lhs - rhs) <= tolerance);
+    }
+
+private:
+    T tolerance;
+};
+
+void test_tolerance_predicate()
+{
+    BOOST_TEST_WITH( 1.0, 1.0, with_tolerance<double>(1e-5) );
+    BOOST_TEST_WITH( 1.0, 1.0 - 1e-6, with_tolerance<double>(1e-5) );
+    BOOST_TEST_WITH( 1.0, 1.0 + 1e-6, with_tolerance<double>(1e-5) );
+}
+
+int main()
+{
+    test_tolerance_predicate();
+
+    return boost::report_errors();
+}