Index: source/third_party/ogre3d_preprocessor/tests/test_Preprocessor.h
===================================================================
--- source/third_party/ogre3d_preprocessor/tests/test_Preprocessor.h
+++ source/third_party/ogre3d_preprocessor/tests/test_Preprocessor.h
@@ -20,6 +20,18 @@
 #include "graphics/PreprocessorWrapper.h"
 #include "third_party/ogre3d_preprocessor/OgreGLSLPreprocessor.h"
 
+#include <boost/algorithm/string/trim.hpp>
+
+namespace
+{
+	// Removes leading and trailing white spaces.
+	std::string Trim(std::string text)
+	{
+		boost::algorithm::trim(text);
+		return text;
+	}
+}
+
 class TestPreprocessor : public CxxTest::TestSuite
 {
 public:
@@ -28,33 +40,88 @@
 		Ogre::CPreprocessor::ErrorHandler = CPreprocessorWrapper::PyrogenesisShaderError;
 	}
 
-	void test_basic()
+	struct PreprocessorResult
+	{
+		std::string output;
+		std::string loggerOutput;
+	};
+
+	PreprocessorResult Parse(const char* in)
 	{
+		PreprocessorResult result;
+		TestLogger logger;
 		Ogre::CPreprocessor preproc;
-		const char* in = "#define TEST 2\n1+1=TEST\n";
 		size_t len = 0;
 		char* out = preproc.Parse(in, strlen(in), len);
-		TS_ASSERT_EQUALS(std::string(out, len), "\n1+1=2\n");
+		result.output = std::string(out, len);
+		result.loggerOutput = logger.GetOutput();
 
 		// Free output if it's not inside the source string
 		if (!(out >= in && out < in + strlen(in)))
 			free(out);
+
+		return result;
+	}
+
+	void test_basic()
+	{
+		PreprocessorResult result = Parse("#define TEST 2\n1+1=TEST\n");
+		TS_ASSERT_EQUALS(result.output, "\n1+1=2\n");
 	}
 
 	void test_error()
 	{
-		TestLogger logger;
+		PreprocessorResult result = Parse("foo\n#if ()\nbar\n");
+		TS_ASSERT_EQUALS(result.output, "");
+		TS_ASSERT_STR_CONTAINS(result.loggerOutput, "ERROR: Preprocessor error: line 2: Unclosed parenthesis in #if expression\n");
+	}
 
-		Ogre::CPreprocessor preproc;
-		const char* in = "foo\n#if ()\nbar\n";
-		size_t len = 0;
-		char* out = preproc.Parse(in, strlen(in), len);
-		TS_ASSERT_EQUALS(std::string(out, len), "");
+	void test_else()
+	{
+		PreprocessorResult result = Parse(R"(
+			#define FOO 0
+			#if FOO
+				#define BAR 0
+			#else
+				#define BAR 42
+			#endif
+			BAR
+		)");
+		TS_ASSERT_EQUALS(Trim(result.output), "42");
+	}
 
-		TS_ASSERT_STR_CONTAINS(logger.GetOutput(), "ERROR: Preprocessor error: line 2: Unclosed parenthesis in #if expression\n");
+	void test_elif()
+	{
+		PreprocessorResult result = Parse(R"(
+			#define FOO 0
+			#if FOO
+				#define BAR 0
+			#elif 1
+				#define BAR 42
+			#endif
+			BAR
+		)");
+		TS_ASSERT_EQUALS(Trim(result.output), "42");
+	}
 
-		// Free output if it's not inside the source string
-		if (!(out >= in && out < in + strlen(in)))
-			free(out);
+	void test_nested_macro()
+	{
+		PreprocessorResult result = Parse(R"(
+			#define FOO(a, b, c, d) func1(a, b + (c * r), 0)
+			#define BAR func2
+			FOO(x, y, BAR(u, v), w)
+		)");
+		TS_ASSERT_EQUALS(Trim(result.output), "func1(x, y + (func2(u, v) * r), 0)");
+	}
+
+	void test_division_by_zero_error()
+	{
+		PreprocessorResult result = Parse(R"(
+			#if 2 / 0
+			42
+			#endif
+		)");
+		TS_ASSERT_EQUALS(Trim(result.output), "");
+		TS_ASSERT_STR_CONTAINS(result.loggerOutput, "ERROR: Preprocessor error: line 2: Division by zero");
 	}
 };