test: add tests in script test suites covering script.cpp live mutants #36360

Kills several live mutants in src/script/script.cpp found on https://bitcoincore.space/public/mutation_data.json. They are:

<details> <summary><a href="https://bitcoincore.space/src/script/script.cpp#2346">script.cpp#2346, 2347, 2348</a>: <code>CScript::IsPayToTaproot</code>: size and opcode check operators</summary>

diff --git a/src/script/script.cpp b/src/script/script.cpp
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -242,3 +242,3 @@ bool CScript::IsPayToTaproot() const
-    return this->size() == 34 &&
-           (*this)[0] == OP_1 &&
-           (*this)[1] == 0x20;
+    return this->size() == 34 ||
+           (*this)[0] == OP_1 &&
+           (*this)[1] != 0x20;

Covered in src/test/script_segwit_tests.cpp (commit accf04f6e).

</details>

<details> <summary><a href="https://bitcoincore.space/src/script/script.cpp#2326">script.cpp#2326</a>: <code>GetSigOpCount</code>: evaluate scriptSig accurately</summary>

diff --git a/src/script/script.cpp b/src/script/script.cpp
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -194,3 +194,3 @@ unsigned int CScript::GetSigOpCount(const CScript& scriptSig) const
     if (!IsPayToScriptHash())
-        return GetSigOpCount(true);
+        return GetSigOpCount(false);
     if (scriptSig.IsPushOnly()) {

Covered in src/test/sigopcount_tests.cpp (commit b9ad09fe3).

</details>

<details> <summary><a href="https://bitcoincore.space/src/script/script.cpp#2325">script.cpp#2325, 2328</a>: <code>GetSigOpCount</code>: multisig boundary checks (OP_1 and OP_16)</summary>

diff --git a/src/script/script.cpp b/src/script/script.cpp
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -179,3 +179,3 @@ unsigned int CScript::GetSigOpCount(bool fAccurate) const
-            if (lastOpcode >= OP_1 && lastOpcode <= OP_16)
+            if (lastOpcode > OP_1 && lastOpcode <= OP_16)
                 n += CScript::DecodeOP_N(lastOpcode);

diff --git a/src/script/script.cpp b/src/script/script.cpp
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -204,3 +204,3 @@ unsigned int CScript::GetSigOpCount(const CScript& scriptSig) const
-                if (opcode > OP_16)
+                if (opcode >= OP_16)
                     return n;

Covered in src/test/sigopcount_tests.cpp (commit b9ad09fe3).

</details>

<details> <summary><a href="https://bitcoincore.space/src/script/script.cpp#2337">script.cpp#2337</a>: <code>IsPayToAnchor</code>: payload byte matching conjunction</summary>

diff --git a/src/script/script.cpp b/src/script/script.cpp
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -231,4 +231,4 @@ bool CScript::IsPayToAnchor(int version, Span<const unsigned char> program)
     return version == 1 &&
            program.size() == 2 &&
-           program[0] == 0x4e &&
+           (program[0] == 0x4e ||
            program[1] == 0x73);

Covered in src/test/script_standard_tests.cpp (commit 559809edd).

</details>

<details> <summary><a href="https://bitcoincore.space/src/script/script.cpp#2365">script.cpp#2365</a>: <code>CScript::HasValidOps</code>: MAX_OPCODE boundary check</summary>

diff --git a/src/script/script.cpp b/src/script/script.cpp
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -311,3 +311,3 @@ bool CScript::HasValidOps() const
     while (GetOp(it, opcode)) {
-        if (opcode > MAX_OPCODE)
+        if (opcode >= MAX_OPCODE)
             return false;

Covered in src/test/script_tests.cpp (commit ec4d7b3bd).

</details>

<details> <summary><a href="https://bitcoincore.space/src/script/script.cpp#2372">script.cpp#2372, 2377, 2380, 2383</a>: <code>CScript::GetOp</code>: truncated pushdata lengths</summary>

diff --git a/src/script/script.cpp b/src/script/script.cpp
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -49,3 +49,3 @@ bool CScript::GetOp(const_iterator& pc, opcodetype& opcodeRet, std::vector<unsi
         if (opcode >= 0 && opcode <= OP_PUSHDATA4) {
-            if (pc + nSize > pend)
+            if (false)
                 return false;

Covered in src/test/script_tests.cpp (commit ec4d7b3bd).

</details>

<details> <summary><a href="https://bitcoincore.space/src/script/script.cpp#2362">script.cpp#2362</a>: <code>CScriptWitness::ToString</code>: stack element delimiter condition</summary>

diff --git a/src/script/script.cpp b/src/script/script.cpp
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -342,3 +342,3 @@ std::string CScriptWitness::ToString() const
     for (unsigned i = 0; i < stack.size(); i++) {
-        if (i)
+        if (1 == 1)
             ret += ", ";

Covered in src/test/script_tests.cpp (commit ec4d7b3bd).

</details>

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For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/36360.

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cc @brunoerg