Merge branch 'master' into dev-modernize

include/internal/catch_run_context.hpp

@@ -40,6 +40,20 @@ namespace Catch {
         std::string& m_targetString;
     };
 
+    // StdErr has two constituent streams in C++, std::cerr and std::clog
+    // This means that we need to redirect 2 streams into 1 to keep proper
+    // order of writes and cannot use StreamRedirect on its own
+    class StdErrRedirect {
+    public:
+        StdErrRedirect(std::string& targetString);
+        ~StdErrRedirect();
+    private:
+        std::streambuf* m_cerrBuf;
+        std::streambuf* m_clogBuf;
+        std::ostringstream m_oss;
+        std::string& m_targetString;
+    };
+
     ///////////////////////////////////////////////////////////////////////////
 
     class RunContext : public IResultCapture, public IRunner {