Fix libsnark dependency build.

This changes libsnark to build in-place, instead of copying first to
a build directory. Previously, modifications made to the original
sources wouldn't get rebuilt without a 'make clean' because users
would be pointing to the copies.

This closes #2689.

src/snark/libsnark/algebra/curves/tests/test_groups.cpp

@@ -0,0 +1,153 @@
+/**
+ *****************************************************************************
+ * @author     This file is part of libsnark, developed by SCIPR Lab
+ *             and contributors (see AUTHORS).
+ * @copyright  MIT license (see LICENSE file)
+ *****************************************************************************/
+#include "common/profiling.hpp"
+#ifdef CURVE_BN128
+#include "algebra/curves/bn128/bn128_pp.hpp"
+#endif
+#include "algebra/curves/alt_bn128/alt_bn128_pp.hpp"
+#include <sstream>
+
+#include <gtest/gtest.h>
+
+using namespace libsnark;
+
+template<typename GroupT>
+void test_mixed_add()
+{
+    GroupT base, el, result;
+
+    base = GroupT::zero();
+    el = GroupT::zero();
+    el.to_special();
+    result = base.mixed_add(el);
+    EXPECT_EQ(result, base + el);
+
+    base = GroupT::zero();
+    el = GroupT::random_element();
+    el.to_special();
+    result = base.mixed_add(el);
+    EXPECT_EQ(result, base + el);
+
+    base = GroupT::random_element();
+    el = GroupT::zero();
+    el.to_special();
+    result = base.mixed_add(el);
+    EXPECT_EQ(result, base + el);
+
+    base = GroupT::random_element();
+    el = GroupT::random_element();
+    el.to_special();
+    result = base.mixed_add(el);
+    EXPECT_EQ(result, base + el);
+
+    base = GroupT::random_element();
+    el = base;
+    el.to_special();
+    result = base.mixed_add(el);
+    EXPECT_EQ(result, base.dbl());
+}
+
+template<typename GroupT>
+void test_group()
+{
+    bigint<1> rand1 = bigint<1>("76749407");
+    bigint<1> rand2 = bigint<1>("44410867");
+    bigint<1> randsum = bigint<1>("121160274");
+
+    GroupT zero = GroupT::zero();
+    EXPECT_EQ(zero, zero);
+    GroupT one = GroupT::one();
+    EXPECT_EQ(one, one);
+    GroupT two = bigint<1>(2l) * GroupT::one();
+    EXPECT_EQ(two, two);
+    GroupT five = bigint<1>(5l) * GroupT::one();
+
+    GroupT three = bigint<1>(3l) * GroupT::one();
+    GroupT four = bigint<1>(4l) * GroupT::one();
+
+    EXPECT_EQ(two+five, three+four);
+
+    GroupT a = GroupT::random_element();
+    GroupT b = GroupT::random_element();
+
+    EXPECT_NE(one, zero);
+    EXPECT_NE(a, zero);
+    EXPECT_NE(a, one);
+
+    EXPECT_NE(b, zero);
+    EXPECT_NE(b, one);
+
+    EXPECT_EQ(a.dbl(), a + a);
+    EXPECT_EQ(b.dbl(), b + b);
+    EXPECT_EQ(one.add(two), three);
+    EXPECT_EQ(two.add(one), three);
+    EXPECT_EQ(a + b, b + a);
+    EXPECT_EQ(a - a, zero);
+    EXPECT_EQ(a - b, a + (-b));
+    EXPECT_EQ(a - b, (-b) + a);
+
+    // handle special cases
+    EXPECT_EQ(zero + (-a), -a);
+    EXPECT_EQ(zero - a, -a);
+    EXPECT_EQ(a - zero, a);
+    EXPECT_EQ(a + zero, a);
+    EXPECT_EQ(zero + a, a);
+
+    EXPECT_EQ((a + b).dbl(), (a + b) + (b + a));
+    EXPECT_EQ(bigint<1>("2") * (a + b), (a + b) + (b + a));
+
+    EXPECT_EQ((rand1 * a) + (rand2 * a), (randsum * a));
+
+    EXPECT_EQ(GroupT::order() * a, zero);
+    EXPECT_EQ(GroupT::order() * one, zero);
+    EXPECT_NE((GroupT::order() * a) - a, zero);
+    EXPECT_NE((GroupT::order() * one) - one, zero);
+
+    test_mixed_add<GroupT>();
+}
+
+template<typename GroupT>
+void test_mul_by_q()
+{
+    GroupT a = GroupT::random_element();
+    EXPECT_EQ((GroupT::base_field_char()*a), a.mul_by_q());
+}
+
+template<typename GroupT>
+void test_output()
+{
+    GroupT g = GroupT::zero();
+
+    for (size_t i = 0; i < 1000; ++i)
+    {
+        std::stringstream ss;
+        ss << g;
+        GroupT gg;
+        ss >> gg;
+        EXPECT_EQ(g, gg);
+        /* use a random point in next iteration */
+        g = GroupT::random_element();
+    }
+}
+
+TEST(algebra, groups)
+{
+    alt_bn128_pp::init_public_params();
+    test_group<G1<alt_bn128_pp> >();
+    test_output<G1<alt_bn128_pp> >();
+    test_group<G2<alt_bn128_pp> >();
+    test_output<G2<alt_bn128_pp> >();
+    test_mul_by_q<G2<alt_bn128_pp> >();
+
+#ifdef CURVE_BN128       // BN128 has fancy dependencies so it may be disabled
+    bn128_pp::init_public_params();
+    test_group<G1<bn128_pp> >();
+    test_output<G1<bn128_pp> >();
+    test_group<G2<bn128_pp> >();
+    test_output<G2<bn128_pp> >();
+#endif
+}