Add a test that all flags are softforks

src/test/script_tests.cpp

@@ -167,6 +167,17 @@ void DoTest(const CScript& scriptPubKey, const CScript& scriptSig, const CScript
     CMutableTransaction tx2 = tx;
     BOOST_CHECK_MESSAGE(VerifyScript(scriptSig, scriptPubKey, &scriptWitness, flags, MutableTransactionSignatureChecker(&tx, 0, txCredit.vout[0].nValue), &err) == expect, message);
     BOOST_CHECK_MESSAGE(err == scriptError, std::string(FormatScriptError(err)) + " where " + std::string(FormatScriptError((ScriptError_t)scriptError)) + " expected: " + message);
+
+    // Verify that removing flags from a passing test or adding flags to a failing test does not change the result.
+    for (int i = 0; i < 16; ++i) {
+        int extra_flags = InsecureRandBits(16);
+        int combined_flags = expect ? (flags & ~extra_flags) : (flags | extra_flags);
+        // Weed out some invalid flag combinations.
+        if (combined_flags & SCRIPT_VERIFY_CLEANSTACK && ~combined_flags & (SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_WITNESS)) continue;
+        if (combined_flags & SCRIPT_VERIFY_WITNESS && ~combined_flags & SCRIPT_VERIFY_P2SH) continue;
+        BOOST_CHECK_MESSAGE(VerifyScript(scriptSig, scriptPubKey, &scriptWitness, combined_flags, MutableTransactionSignatureChecker(&tx, 0, txCredit.vout[0].nValue), &err) == expect, message + strprintf(" (with flags %x)", combined_flags));
+    }
+
 #if defined(HAVE_CONSENSUS_LIB)
     CDataStream stream(SER_NETWORK, PROTOCOL_VERSION);
     stream << tx2;