First attempt at data generator support

The support is to be considered experimental, that is, the interfaces,
the first party generators and helper functions can change or be removed
at any point in time.

Related to #850

projects/SelfTest/IntrospectiveTests/GeneratorsImpl.tests.cpp

@@ -0,0 +1,93 @@
+#include "catch.hpp"
+
+// Tests of generartor implementation details
+
+TEST_CASE("Generators impl", "[impl]") {
+    using namespace Catch::Generators;
+
+    SECTION( "range" ) {
+        auto gen = range(1,3);
+
+        CHECK( gen.size() == 2 );
+
+        CHECK( gen[0] == 1 );
+        CHECK( gen[1] == 2 );
+    }
+    SECTION( "fixed values" ) {
+        auto gen = values( { 3, 1, 4, 1 } );
+
+        CHECK( gen.size() == 4 );
+        CHECK( gen[0] == 3 );
+        CHECK( gen[1] == 1 );
+        CHECK( gen[2] == 4 );
+        CHECK( gen[3] == 1 );
+    }
+    SECTION( "combined" ) {
+        auto gen = makeGenerators( range( 1, 3 ), values( { 9, 7 } ) );
+
+        CHECK( gen.size() == 4 );
+        CHECK( gen[0] == 1 );
+        CHECK( gen[1] == 2 );
+        CHECK( gen[2] == 9 );
+        CHECK( gen[3] == 7 );
+    }
+
+    SECTION( "values" ) {
+        auto gen = makeGenerators( 3, 1 );
+
+        CHECK( gen.size() == 2 );
+        CHECK( gen[0] == 3 );
+        CHECK( gen[1] == 1 );
+    }
+    SECTION( "values2" ) {
+        auto gen = makeGenerators( 3, 1 );
+
+        CHECK( gen.size() == 2 );
+        CHECK( gen[0] == 3 );
+        CHECK( gen[1] == 1 );
+    }
+
+
+    SECTION( "type erasure" ) {
+        auto gen = makeGenerators( range( 7, 10 ), 11 );
+
+        // Make type erased version
+        auto dynCopy = pf::make_unique<Generators<int>>( std::move( gen ) );
+        std::unique_ptr<GeneratorBase const> base = std::move( dynCopy );
+
+        // Only thing we can do is ask for the size
+        CHECK( base->size() == 4 );
+
+        // Restore typed version
+        auto typed = dynamic_cast<Generators<int> const*>( base.get() );
+        REQUIRE( typed );
+        CHECK( typed->size() == 4 );
+        CHECK( (*typed)[0] == 7 );
+        CHECK( (*typed)[3] == 11 );
+    }
+}
+
+TEST_CASE("Generators impl - random", "[approvals]") {
+    using namespace Catch::Generators;
+
+    SECTION( "random range" ) {
+        auto gen = random( 3, 9 );
+
+        CHECK( gen.size() == 6 );
+        for( size_t i = 0; i < 6; ++i ) {
+            CHECK( gen[i] >= 3 );
+            CHECK( gen[i] <= 8 );
+            if( i > 0 )
+                CHECK( gen[i] != gen[i-1] );
+        }
+    }
+    SECTION( "random selection" ) {
+        auto gen = random<int>( 10 );
+
+        CHECK( gen.size() == 10 );
+        for( size_t i = 0; i < 10; ++i ) {
+            if( i > 0 )
+                CHECK( gen[i] != gen[i-1] );
+        }
+    }
+}