test: remove test-only uint256S

uint256S was previously deprecated for being unsafe. All non-test
usage has already been removed in earlier commits.

1. Tests now use uint256::FromHex() or other constructors wherever
possible without further modification.
2. Tests that can't use uint256::FromHex() because they use input
with non-hex digit characters are
  a) modified by dropping the non-hex digit characters if that
     provides useful test coverage.
  b) dropped if the test without non-hex digit characters does
     not provide useful test coverage, e.g. because it is now
     duplicated.

Additionally, use BOOST_CHECK_EQUAL where relevant on touched lines
to make error messages more readable.

src/test/fuzz/hex.cpp

@@ -37,7 +37,6 @@ FUZZ_TARGET(hex)
     if (const auto result{uint256::FromUserHex(random_hex_string)}) {
         assert(uint256::FromHex(result->ToString()));
     }
-    (void)uint256S(random_hex_string);
     try {
         (void)HexToPubKey(random_hex_string);
     } catch (const UniValue&) {

src/test/fuzz/integer.cpp

@@ -140,7 +140,7 @@ FUZZ_TARGET(integer, .init = initialize_integer)
 
     const arith_uint256 au256 = UintToArith256(u256);
     assert(ArithToUint256(au256) == u256);
-    assert(uint256S(au256.GetHex()) == u256);
+    assert(uint256::FromHex(au256.GetHex()).value() == u256);
     (void)au256.bits();
     (void)au256.GetCompact(/* fNegative= */ false);
     (void)au256.GetCompact(/* fNegative= */ true);

src/test/uint256_tests.cpp

@@ -92,18 +92,12 @@ BOOST_AUTO_TEST_CASE( basics ) // constructors, equality, inequality
     BOOST_CHECK_NE(MaxL, ZeroL); BOOST_CHECK_NE(MaxS, ZeroS);
 
     // String Constructor and Copy Constructor
-    BOOST_CHECK_EQUAL(uint256S("0x"+R1L.ToString()), R1L);
+    BOOST_CHECK_EQUAL(uint256::FromHex(R1L.ToString()).value(), R1L);
-    BOOST_CHECK_EQUAL(uint256S("0x"+R2L.ToString()), R2L);
+    BOOST_CHECK_EQUAL(uint256::FromHex(R2L.ToString()).value(), R2L);
-    BOOST_CHECK_EQUAL(uint256S("0x"+ZeroL.ToString()), ZeroL);
+    BOOST_CHECK_EQUAL(uint256::FromHex(ZeroL.ToString()).value(), ZeroL);
-    BOOST_CHECK_EQUAL(uint256S("0x"+OneL.ToString()), OneL);
+    BOOST_CHECK_EQUAL(uint256::FromHex(OneL.ToString()).value(), OneL);
-    BOOST_CHECK_EQUAL(uint256S("0x"+MaxL.ToString()), MaxL);
+    BOOST_CHECK_EQUAL(uint256::FromHex(MaxL.ToString()).value(), MaxL);
-    BOOST_CHECK_EQUAL(uint256S(R1L.ToString()), R1L);
+    BOOST_CHECK_EQUAL(uint256::FromHex(R1ArrayHex).value(), R1L);
-    BOOST_CHECK_EQUAL(uint256S("   0x"+R1L.ToString()+"   "), R1L);
-    BOOST_CHECK_EQUAL(uint256S("   0x"+R1L.ToString()+"-trash;%^&   "), R1L);
-    BOOST_CHECK_EQUAL(uint256S("\t \n  \n \f\n\r\t\v\t   0x"+R1L.ToString()+"  \t \n  \n \f\n\r\t\v\t "), R1L);
-    BOOST_CHECK_EQUAL(uint256S(""), ZeroL);
-    BOOST_CHECK_EQUAL(uint256S("1"), OneL);
-    BOOST_CHECK_EQUAL(R1L, uint256S(R1ArrayHex));
     BOOST_CHECK_EQUAL(uint256(R1L), R1L);
     BOOST_CHECK_EQUAL(uint256(ZeroL), ZeroL);
     BOOST_CHECK_EQUAL(uint256(OneL), OneL);
@@ -282,48 +276,20 @@ BOOST_AUTO_TEST_CASE( operator_with_self )
 #    pragma clang diagnostic push
 #    pragma clang diagnostic ignored "-Wself-assign-overloaded"
 #endif
-    arith_uint256 v = UintToArith256(uint256S("02"));
+    arith_uint256 v{2};
     v *= v;
-    BOOST_CHECK_EQUAL(v, UintToArith256(uint256S("04")));
+    BOOST_CHECK_EQUAL(v, arith_uint256{4});
     v /= v;
-    BOOST_CHECK_EQUAL(v, UintToArith256(uint256S("01")));
+    BOOST_CHECK_EQUAL(v, arith_uint256{1});
     v += v;
-    BOOST_CHECK_EQUAL(v, UintToArith256(uint256S("02")));
+    BOOST_CHECK_EQUAL(v, arith_uint256{2});
     v -= v;
-    BOOST_CHECK_EQUAL(v, UintToArith256(uint256S("0")));
+    BOOST_CHECK_EQUAL(v, arith_uint256{0});
 #if defined(__clang__)
 #    pragma clang diagnostic pop
 #endif
 }
 
-BOOST_AUTO_TEST_CASE(parse)
-{
-    {
-        std::string s_12{"0000000000000000000000000000000000000000000000000000000000000012"};
-        BOOST_CHECK_EQUAL(uint256S("12\0").GetHex(), s_12);
-        BOOST_CHECK_EQUAL(uint256S(std::string_view{"12\0", 3}).GetHex(), s_12);
-        BOOST_CHECK_EQUAL(uint256S("0x12").GetHex(), s_12);
-        BOOST_CHECK_EQUAL(uint256S(" 0x12").GetHex(), s_12);
-        BOOST_CHECK_EQUAL(uint256S(" 12").GetHex(), s_12);
-    }
-    {
-        std::string s_1{uint256::ONE.GetHex()};
-        BOOST_CHECK_EQUAL(uint256S("1\0").GetHex(), s_1);
-        BOOST_CHECK_EQUAL(uint256S(std::string_view{"1\0", 2}).GetHex(), s_1);
-        BOOST_CHECK_EQUAL(uint256S("0x1").GetHex(), s_1);
-        BOOST_CHECK_EQUAL(uint256S(" 0x1").GetHex(), s_1);
-        BOOST_CHECK_EQUAL(uint256S(" 1").GetHex(), s_1);
-    }
-    {
-        std::string s_0{uint256::ZERO.GetHex()};
-        BOOST_CHECK_EQUAL(uint256S("\0").GetHex(), s_0);
-        BOOST_CHECK_EQUAL(uint256S(std::string_view{"\0", 1}).GetHex(), s_0);
-        BOOST_CHECK_EQUAL(uint256S("0x").GetHex(), s_0);
-        BOOST_CHECK_EQUAL(uint256S(" 0x").GetHex(), s_0);
-        BOOST_CHECK_EQUAL(uint256S(" ").GetHex(), s_0);
-    }
-}
-
 /**
  * Implemented as a templated function so it can be reused by other classes that have a FromHex()
  * method that wraps base_blob::FromHex(), such as transaction_identifier::FromHex().

src/uint256.h

@@ -199,14 +199,4 @@ public:
     static const uint256 ONE;
 };
 
-/* uint256 from std::string_view, containing byte-reversed hex encoding.
- * DEPRECATED. Unlike FromHex this accepts any invalid input, thus it is fragile and deprecated!
- */
-inline uint256 uint256S(std::string_view str)
-{
-    uint256 rv;
-    rv.SetHexDeprecated(str);
-    return rv;
-}
-
 #endif // BITCOIN_UINT256_H