Added API in lightweight_test to obtain the number of test failures.

The new API allows to check if the number of check failures satisfies
a certain condition. The report_errors function returns test_report,
which allows to obtain the error count. It also protects against
unintended comparisons to the error count, which was a misconception
before.

Also added a get_error_count function to explicitly query for the current
number of errors.

doc/lightweight_test.qbk

@@ -49,7 +49,9 @@ When using `lightweight_test.hpp`, *do not forget* to
 
 namespace boost
 {
-    int report_errors();
+    class test_report;
+    int get_error_count();
+    test_report report_errors();
 }
 ``
 
@@ -212,10 +214,47 @@ nothing and `expr` is not evaluated.
 [section report_errors]
 
 ``
-int boost::report_errors()
+boost::test_report boost::report_errors()
 ``
 
-Return the error count from `main`.
+Returns the test report. The report can be converted to an `int` to be returned from `main`.
+
+[endsect]
+
+[section test_report]
+
+``
+class test_report
+{
+public:
+    int error_count() const noexcept;
+    operator int() const noexcept;
+};
+``
+
+Contains information about test results.
+
+``
+int test_report::error_count() const noexcept;
+``
+
+The method returns the number of failed checks.
+
+``
+test_report::operator int() const noexcept;
+``
+
+Returns 0 if there are no failed checks and 1 otherwise. This operator is suitable for obtaining result code to return from `main`.
+
+[endsect]
+
+[section get_error_count]
+
+``
+int boost::get_error_count();
+``
+
+Returns the number of failed checks.
 
 [endsect]
 

include/boost/core/lightweight_test.hpp

@@ -373,7 +373,58 @@ void test_all_with_impl(FormattedOutputFunction& output,
 
 } // namespace detail
 
-inline int report_errors()
+//! Testing report
+class test_report
+{
+private:
+    int m_error_count;
+
+public:
+    explicit test_report(int error_count) BOOST_NOEXCEPT :
+        m_error_count(error_count)
+    {
+    }
+
+    //! Returns the number of test errors
+    int error_count() const BOOST_NOEXCEPT { return m_error_count; }
+
+    //! Operator for converting to result of main()
+    operator int () const BOOST_NOEXCEPT { return m_error_count > 0 ? 1 : 0; }
+
+    // Protection against comparing report_errors() with the number of errors. Earlier versions of report_errors() did not return
+    // the number of errors, so such comparisons used to give a wrong result and now cause a hard compile time error.
+    // Call report_errors().error_count() if you need to check the error count, but make sure you return the correct value from main().
+    BOOST_DELETED_FUNCTION(bool operator== (int))
+    BOOST_DELETED_FUNCTION(bool operator!= (int))
+    BOOST_DELETED_FUNCTION(bool operator< (int))
+    BOOST_DELETED_FUNCTION(bool operator> (int))
+    BOOST_DELETED_FUNCTION(bool operator>= (int))
+    BOOST_DELETED_FUNCTION(bool operator<= (int))
+};
+
+#if !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
+#define BOOST_LIGHTWEIGHT_TEST_DELETED_FUNCTION_MARK = delete
+#else
+#define BOOST_LIGHTWEIGHT_TEST_DELETED_FUNCTION_MARK
+#endif
+
+bool operator== (int, test_report const&) BOOST_LIGHTWEIGHT_TEST_DELETED_FUNCTION_MARK;
+bool operator!= (int, test_report const&) BOOST_LIGHTWEIGHT_TEST_DELETED_FUNCTION_MARK;
+bool operator< (int, test_report const&) BOOST_LIGHTWEIGHT_TEST_DELETED_FUNCTION_MARK;
+bool operator> (int, test_report const&) BOOST_LIGHTWEIGHT_TEST_DELETED_FUNCTION_MARK;
+bool operator<= (int, test_report const&) BOOST_LIGHTWEIGHT_TEST_DELETED_FUNCTION_MARK;
+bool operator>= (int, test_report const&) BOOST_LIGHTWEIGHT_TEST_DELETED_FUNCTION_MARK;
+
+#undef BOOST_LIGHTWEIGHT_TEST_DELETED_FUNCTION_MARK
+
+//! Returns the number of test errors encountered
+inline int get_error_count() BOOST_NOEXCEPT
+{
+    return boost::detail::test_results().errors();
+}
+
+//! Prints the number of test errors and returns test report suitable for returning from main()
+inline test_report report_errors()
 {
     boost::detail::test_result& result = boost::detail::test_results();
     result.done();
@@ -383,14 +434,14 @@ inline int report_errors()
     {
         BOOST_LIGHTWEIGHT_TEST_OSTREAM
           << "No errors detected." << std::endl;
-        return 0;
     }
     else
     {
         BOOST_LIGHTWEIGHT_TEST_OSTREAM
           << errors << " error" << (errors == 1? "": "s") << " detected." << std::endl;
-        return 1;
     }
+
+    return test_report(errors);
 }
 
 } // namespace boost

test/Jamfile.v2

@@ -77,8 +77,8 @@ run lightweight_test_test3.cpp ;
 run lightweight_test_test4.cpp ;
 run lightweight_test_test5.cpp ;
 
-run-fail lightweight_test_all_eq_test.cpp ;
+run lightweight_test_all_eq_test.cpp ;
-run-fail lightweight_test_all_with_fail.cpp ;
+run lightweight_test_all_with_fail.cpp ;
 
 run-fail lightweight_test_fail.cpp ;
 run-fail lightweight_test_fail2.cpp ;

test/lightweight_test_all_eq_test.cpp

@@ -120,5 +120,5 @@ int main()
         ++test_cases;
     }
 
-    return boost::report_errors() == test_cases;
+    return boost::report_errors().error_count() == test_cases ? 0 : 1;
 }

test/lightweight_test_all_with_fail.cpp

@@ -101,5 +101,5 @@ int main()
     test_cases += fail_vector();
     test_cases += fail_tolerance_predicate();
 
-    return boost::report_errors() == test_cases;
+    return boost::report_errors().error_count() == test_cases ? 0 : 1;
 }

test/lightweight_test_test5.cpp

@@ -64,5 +64,5 @@ int main()
 
 #endif
 
-    return boost::report_errors() == expected;
+    return boost::report_errors().error_count() == expected ? 0 : 1;
 }