Invoke the merkle_hash API in librustzcash via test suite.

src/Makefile.gtest.include

@@ -40,6 +40,7 @@ zcash_gtest_SOURCES += \
 	gtest/test_libzcash_utils.cpp \
 	gtest/test_proofs.cpp \
 	gtest/test_paymentdisclosure.cpp \
+	gtest/test_pedersen_hash.cpp \
 	gtest/test_checkblock.cpp
 if ENABLE_WALLET
 zcash_gtest_SOURCES += \

src/gtest/test_pedersen_hash.cpp

@@ -0,0 +1,15 @@
+#include <gtest/gtest.h>
+#include "librustzcash.h"
+#include "uint256.h"
+
+TEST(PedersenHash, TestAPI) {
+    const uint256 a = uint256S("0acaa62d40fcdd9192ed35ea9df31660ccf7f6c60566530faaa444fb5d0d410e");
+    const uint256 b = uint256S("6041357de59ba64959d1b60f93de24dfe5ea1e26ed9e8a73d35b225a1845ba70");
+    uint256 result;
+
+    librustzcash_merkle_hash(25, a.begin(), b.begin(), result.begin());
+
+    uint256 expected_result = uint256S("4253b36834b3f64cc6182f1816911e1c9460cb88afeafb155244dd0038ad4717");
+
+    ASSERT_TRUE(result == expected_result);
+}