Removed Boost dependency in unit tests.

Some of the unit tests depended on Boost’s null_sink to redirect the
unwanted test output to /dev/null. This commit adds a simple
NullOutputStream as a replacement and removes the obsolete Boost
includes.

tests/NullOutputStream.h

@@ -0,0 +1,44 @@
+#ifndef __PLASP__TESTS__NULL_OUTPUT_STREAM_H
+#define __PLASP__TESTS__NULL_OUTPUT_STREAM_H
+
+#include <iostream>
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// NullOutputStream
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class NullStreamBuffer : public std::streambuf
+{
+	private:
+		char dummyBuffer[64];
+
+	protected:
+		virtual int overflow(int c)
+		{
+			setp(dummyBuffer, dummyBuffer + sizeof(dummyBuffer));
+			return (c == traits_type::eof()) ? '\0' : c;
+		}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class NullOutputStream : public std::ostream
+{
+	public:
+		NullOutputStream()
+		:	std::ostream(&m_nullStreamBuffer)
+		{
+		}
+
+		NullStreamBuffer *rdbuf() const
+		{
+			return &m_nullStreamBuffer;
+		}
+
+	private:
+		mutable NullStreamBuffer m_nullStreamBuffer;
+};
+
+#endif

tests/TestPDDLTranslation.cpp

@@ -1,7 +1,6 @@
 #include <catch.hpp>
 
-#include <boost/iostreams/stream.hpp>
-#include <boost/iostreams/device/null.hpp>
+#include <iostream>
 
 #include <colorlog/Logger.h>
 
@@ -11,15 +10,17 @@
 
 #include <plasp/pddl/TranslatorASP.h>
 
-boost::iostreams::stream<boost::iostreams::null_sink> nullStream((boost::iostreams::null_sink()));
+#include "NullOutputStream.h"
+
 const pddl::Context::WarningCallback ignoreWarnings = [](const auto &, const auto &){};
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
 TEST_CASE("[PDDL translation] Former issues are fixed", "[PDDL translation]")
 {
-	// TODO: refactor
-	colorlog::Logger logger(nullStream, nullStream);
+	NullOutputStream nullOutputStream;
+
+	colorlog::Logger logger(nullOutputStream, nullOutputStream);
 	pddl::Tokenizer tokenizer;
 	pddl::Context context(std::move(tokenizer), ignoreWarnings);