script: Add test for CScriptNum

Because this class replaces some usages of CBigNum, tests have been added to
verify that they function the same way. The only difference in their usage is
the handling of out-of-range numbers.

While operands are constrained to [-0x7FFFFFFF,0x7FFFFFFF], the results may
overflow. The overflowing result is technically unbounded, but in practice
it can be no bigger than the result of an operation on two operands. This
implementation limits them to the size of an int64.

CBigNum was unaware of this constraint, so it allowed for unbounded results,
which were then checked before use. CScriptNum asserts if an arithmetic
operation will overflow an int64_t, since scripts are not able to reach those
numbers anyway. Additionally, CScriptNum will throw an exception when
constructed from a vector containing more than 4 bytes This mimics the previous
CastToBigNum behavior.

2 files changed, 197 insertions, 0 deletions

diff --git a/src/test/Makefile.am b/src/test/Makefile.am
index b375ba1306..e12f4904f1 100644
--- a/src/test/Makefile.am
+++ b/src/test/Makefile.am
@@ -61,6 +61,7 @@ test_bitcoin_SOURCES = \
   transaction_tests.cpp \
   uint256_tests.cpp \
   util_tests.cpp \
+  scriptnum_tests.cpp \
   sighash_tests.cpp \
   $(JSON_TEST_FILES) $(RAW_TEST_FILES)
 
diff --git a/src/test/scriptnum_tests.cpp b/src/test/scriptnum_tests.cpp
new file mode 100644
index 0000000000..cd194cc4d9
--- /dev/null
+++ b/src/test/scriptnum_tests.cpp
@@ -0,0 +1,196 @@
+// Copyright (c) 2012-2014 The Bitcoin Core developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "bignum.h"
+#include "script.h"
+#include <boost/test/unit_test.hpp>
+#include <limits.h>
+#include <stdint.h>
+BOOST_AUTO_TEST_SUITE(scriptnum_tests)
+
+static const int64_t values[] = \
+{ 0, 1, CHAR_MIN, CHAR_MAX, UCHAR_MAX, SHRT_MIN, USHRT_MAX, INT_MIN, INT_MAX, UINT_MAX, LONG_MIN, LONG_MAX };
+static const int64_t offsets[] = { 1, 0x79, 0x80, 0x81, 0xFF, 0x7FFF, 0x8000, 0xFFFF, 0x10000};
+
+static bool verify(const CBigNum& bignum, const CScriptNum& scriptnum)
+{
+    return bignum.getvch() == scriptnum.getvch() && bignum.getint() == scriptnum.getint();
+}
+
+static void CheckCreateVch(const int64_t& num)
+{
+    CBigNum bignum(num);
+    CScriptNum scriptnum(num);
+    BOOST_CHECK(verify(bignum, scriptnum));
+
+    CBigNum bignum2(bignum.getvch());
+    CScriptNum scriptnum2(scriptnum.getvch());
+    BOOST_CHECK(verify(bignum2, scriptnum2));
+
+    CBigNum bignum3(scriptnum2.getvch());
+    CScriptNum scriptnum3(bignum2.getvch());
+    BOOST_CHECK(verify(bignum3, scriptnum3));
+}
+
+static void CheckCreateInt(const int64_t& num)
+{
+    CBigNum bignum(num);
+    CScriptNum scriptnum(num);
+    BOOST_CHECK(verify(bignum, scriptnum));
+    BOOST_CHECK(verify(bignum.getint(), CScriptNum(scriptnum.getint())));
+    BOOST_CHECK(verify(scriptnum.getint(), CScriptNum(bignum.getint())));
+    BOOST_CHECK(verify(CBigNum(scriptnum.getint()).getint(), CScriptNum(CScriptNum(bignum.getint()).getint())));
+}
+
+
+static void CheckAdd(const int64_t& num1, const int64_t& num2)
+{
+    const CBigNum bignum1(num1);
+    const CBigNum bignum2(num2);
+    const CScriptNum scriptnum1(num1);
+    const CScriptNum scriptnum2(num2);
+    CBigNum bignum3(num1);
+    CBigNum bignum4(num1);
+    CScriptNum scriptnum3(num1);
+    CScriptNum scriptnum4(num1);
+
+    // int64_t overflow is undefined.
+    bool invalid = (((num2 > 0) && (num1 > (std::numeric_limits<int64_t>::max() - num2))) ||
+                    ((num2 < 0) && (num1 < (std::numeric_limits<int64_t>::min() - num2))));
+    if (!invalid)
+    {
+        BOOST_CHECK(verify(bignum1 + bignum2, scriptnum1 + scriptnum2));
+        BOOST_CHECK(verify(bignum1 + bignum2, scriptnum1 + num2));
+        BOOST_CHECK(verify(bignum1 + bignum2, scriptnum2 + num1));
+    }
+}
+
+static void CheckNegate(const int64_t& num)
+{
+    const CBigNum bignum(num);
+    const CScriptNum scriptnum(num);
+
+    // -INT64_MIN is undefined
+    if (num != std::numeric_limits<int64_t>::min())
+        BOOST_CHECK(verify(-bignum, -scriptnum));
+}
+
+static void CheckSubtract(const int64_t& num1, const int64_t& num2)
+{
+    const CBigNum bignum1(num1);
+    const CBigNum bignum2(num2);
+    const CScriptNum scriptnum1(num1);
+    const CScriptNum scriptnum2(num2);
+    bool invalid = false;
+
+    // int64_t overflow is undefined.
+    invalid = ((num2 > 0 && num1 < std::numeric_limits<int64_t>::min() + num2) ||
+               (num2 < 0 && num1 > std::numeric_limits<int64_t>::max() + num2));
+    if (!invalid)
+    {
+        BOOST_CHECK(verify(bignum1 - bignum2, scriptnum1 - scriptnum2));
+        BOOST_CHECK(verify(bignum1 - bignum2, scriptnum1 - num2));
+    }
+
+    invalid = ((num1 > 0 && num2 < std::numeric_limits<int64_t>::min() + num1) ||
+               (num1 < 0 && num2 > std::numeric_limits<int64_t>::max() + num1));
+    if (!invalid)
+    {
+        BOOST_CHECK(verify(bignum2 - bignum1, scriptnum2 - scriptnum1));
+        BOOST_CHECK(verify(bignum2 - bignum1, scriptnum2 - num1));
+    }
+}
+
+static void CheckCompare(const int64_t& num1, const int64_t& num2)
+{
+    const CBigNum bignum1(num1);
+    const CBigNum bignum2(num2);
+    const CScriptNum scriptnum1(num1);
+    const CScriptNum scriptnum2(num2);
+
+    BOOST_CHECK((bignum1 == bignum1) == (scriptnum1 == scriptnum1));
+    BOOST_CHECK((bignum1 != bignum1) ==  (scriptnum1 != scriptnum1));
+    BOOST_CHECK((bignum1 < bignum1) ==  (scriptnum1 < scriptnum1));
+    BOOST_CHECK((bignum1 > bignum1) ==  (scriptnum1 > scriptnum1));
+    BOOST_CHECK((bignum1 >= bignum1) ==  (scriptnum1 >= scriptnum1));
+    BOOST_CHECK((bignum1 <= bignum1) ==  (scriptnum1 <= scriptnum1));
+
+    BOOST_CHECK((bignum1 == bignum1) == (scriptnum1 == num1));
+    BOOST_CHECK((bignum1 != bignum1) ==  (scriptnum1 != num1));
+    BOOST_CHECK((bignum1 < bignum1) ==  (scriptnum1 < num1));
+    BOOST_CHECK((bignum1 > bignum1) ==  (scriptnum1 > num1));
+    BOOST_CHECK((bignum1 >= bignum1) ==  (scriptnum1 >= num1));
+    BOOST_CHECK((bignum1 <= bignum1) ==  (scriptnum1 <= num1));
+
+    BOOST_CHECK((bignum1 == bignum2) ==  (scriptnum1 == scriptnum2));
+    BOOST_CHECK((bignum1 != bignum2) ==  (scriptnum1 != scriptnum2));
+    BOOST_CHECK((bignum1 < bignum2) ==  (scriptnum1 < scriptnum2));
+    BOOST_CHECK((bignum1 > bignum2) ==  (scriptnum1 > scriptnum2));
+    BOOST_CHECK((bignum1 >= bignum2) ==  (scriptnum1 >= scriptnum2));
+    BOOST_CHECK((bignum1 <= bignum2) ==  (scriptnum1 <= scriptnum2));
+
+    BOOST_CHECK((bignum1 == bignum2) ==  (scriptnum1 == num2));
+    BOOST_CHECK((bignum1 != bignum2) ==  (scriptnum1 != num2));
+    BOOST_CHECK((bignum1 < bignum2) ==  (scriptnum1 < num2));
+    BOOST_CHECK((bignum1 > bignum2) ==  (scriptnum1 > num2));
+    BOOST_CHECK((bignum1 >= bignum2) ==  (scriptnum1 >= num2));
+    BOOST_CHECK((bignum1 <= bignum2) ==  (scriptnum1 <= num2));
+}
+
+static void RunCreate(const int64_t& num)
+{
+    CheckCreateInt(num);
+    CScriptNum scriptnum(num);
+    if (scriptnum.getvch().size() <= CScriptNum::nMaxNumSize)
+        CheckCreateVch(num);
+    else
+    {
+        BOOST_CHECK_THROW (CheckCreateVch(num), scriptnum_error);
+    }
+}
+
+static void RunOperators(const int64_t& num1, const int64_t& num2)
+{
+    CheckAdd(num1, num2);
+    CheckSubtract(num1, num2);
+    CheckNegate(num1);
+    CheckCompare(num1, num2);
+}
+
+BOOST_AUTO_TEST_CASE(creation)
+{
+    for(size_t i = 0; i < sizeof(values) / sizeof(values[0]); ++i)
+    {
+        for(size_t j = 0; j < sizeof(offsets) / sizeof(offsets[0]); ++j)
+        {
+            RunCreate(values[i]);
+            RunCreate(values[i] + offsets[j]);
+            RunCreate(values[i] - offsets[j]);
+        }
+    }
+}
+
+BOOST_AUTO_TEST_CASE(operators)
+{
+    for(size_t i = 0; i < sizeof(values) / sizeof(values[0]); ++i)
+    {
+        for(size_t j = 0; j < sizeof(offsets) / sizeof(offsets[0]); ++j)
+        {
+            RunOperators(values[i], values[i]);
+            RunOperators(values[i], -values[i]);
+            RunOperators(values[i], values[j]);
+            RunOperators(values[i], -values[j]);
+            RunOperators(values[i] + values[j], values[j]);
+            RunOperators(values[i] + values[j], -values[j]);
+            RunOperators(values[i] - values[j], values[j]);
+            RunOperators(values[i] - values[j], -values[j]);
+            RunOperators(values[i] + values[j], values[i] + values[j]);
+            RunOperators(values[i] + values[j], values[i] - values[j]);
+            RunOperators(values[i] - values[j], values[i] + values[j]);
+            RunOperators(values[i] - values[j], values[i] - values[j]);
+        }
+    }
+}
+
+BOOST_AUTO_TEST_SUITE_END()