Allow testing ordering to be specified as declaration, lexicographical, or random. Allow random seed to be specified

include/internal/catch_interfaces_config.h

@@ -32,6 +32,11 @@ namespace Catch {
         Always,
         Never
     }; };
+    struct RunTests { enum InWhatOrder {
+        InDeclarationOrder,
+        InLexicographicalOrder,
+        InRandomOrder
+    }; };
 
     class TestSpec;
 
@@ -49,6 +54,8 @@ namespace Catch {
         virtual bool showInvisibles() const = 0;
         virtual ShowDurations::OrNot showDurations() const = 0;
         virtual TestSpec const& testSpec() const = 0;
+        virtual RunTests::InWhatOrder runOrder() const = 0;
+        virtual unsigned int rngSeed() const = 0;
     };
 }