Merge #12742: Make FastRandomContext support standard C++11 RNG interface

1ec1602a45 Make FastRandomContext support standard C++11 RNG interface (Pieter Wuille)

Pull request description:

  This makes it possible to plug it into the various standard C++11 random distribution algorithms and other functions like `std::shuffle`.

Tree-SHA512: 935eae9c4fae31e1964c16d9cf9d0fcfa899e04567f010d8b3e1ff824e55e2392aa838ba743d03c1b2a5010c5b8da04343f453983dfeed83747d85828a564713

src/test/random_tests.cpp

@@ -8,6 +8,9 @@
 
 #include <boost/test/unit_test.hpp>
 
+#include <random>
+#include <algorithm>
+
 BOOST_FIXTURE_TEST_SUITE(random_tests, BasicTestingSetup)
 
 BOOST_AUTO_TEST_CASE(osrandom_tests)
@@ -57,4 +60,23 @@ BOOST_AUTO_TEST_CASE(fastrandom_randbits)
     }
 }
 
+/** Does-it-compile test for compatibility with standard C++11 RNG interface. */
+BOOST_AUTO_TEST_CASE(stdrandom_test)
+{
+    FastRandomContext ctx;
+    std::uniform_int_distribution<int> distribution(3, 9);
+    for (int i = 0; i < 100; ++i) {
+        int x = distribution(ctx);
+        BOOST_CHECK(x >= 3);
+        BOOST_CHECK(x <= 9);
+
+        std::vector<int> test{1,2,3,4,5,6,7,8,9,10};
+        std::shuffle(test.begin(), test.end(), ctx);
+        for (int j = 1; j <= 10; ++j) {
+            BOOST_CHECK(std::find(test.begin(), test.end(), j) != test.end());
+        }
+    }
+
+}
+
 BOOST_AUTO_TEST_SUITE_END()