reseeds rng before each test case and provides access to seed through Catch::rngSeed() function

include/catch_runner.hpp

@@ -198,7 +198,7 @@ namespace Catch {
                 if( m_configData.filenamesAsTags )
                     applyFilenamesAsTags();
                 
-                std::srand( m_configData.rngSeed );
+                seedRng( *m_config );
 
                 Runner runner( m_config );
 

include/internal/catch_common.h

@@ -22,6 +22,8 @@
 #include "catch_compiler_capabilities.h"
 
 namespace Catch {
+    
+    struct IConfig;
 
     class NonCopyable {
 #ifdef CATCH_CONFIG_CPP11_GENERATED_METHODS
@@ -109,6 +111,9 @@ namespace Catch {
 
     void throwLogicError( std::string const& message, SourceLineInfo const& locationInfo );
 
+    void seedRng( IConfig const& config );
+    unsigned int rngSeed();
+    
     // Use this in variadic streaming macros to allow
     //    >> +StreamEndStop
     // as well as

include/internal/catch_common.hpp

@@ -82,6 +82,14 @@ namespace Catch {
         return line < other.line || ( line == other.line  && file < other.file );
     }
 
+    void seedRng( IConfig const& config ) {
+        if( config.rngSeed() != 0 )
+            std::srand( config.rngSeed() );
+    }
+    unsigned int rngSeed() {
+        return getCurrentContext().getConfig()->rngSeed();
+    }
+
     std::ostream& operator << ( std::ostream& os, SourceLineInfo const& info ) {
 #ifndef __GNUG__
         os << info.file << "(" << info.line << ")";

include/internal/catch_runner_impl.hpp

@@ -259,6 +259,8 @@ namespace Catch {
                 m_lastAssertionInfo = AssertionInfo( "TEST_CASE", testCaseInfo.lineInfo, "", ResultDisposition::Normal );
                 TestCaseTracker::Guard guard( *m_testCaseTracker );
 
+                seedRng( *m_config );
+                
                 Timer timer;
                 timer.start();
                 if( m_reporter->getPreferences().shouldRedirectStdOut ) {

include/internal/catch_test_case_registry_impl.hpp

@@ -90,6 +90,8 @@ namespace Catch {
                     break;
                 case RunTests::InRandomOrder:
                 {
+                    seedRng( config );
+                    
                     RandomNumberGenerator rng;
                     std::random_shuffle( matchingTestCases.begin(), matchingTestCases.end(), rng );
                 }