refactor: Enable more clang-tidy readability checks (#6595)

Co-authored-by: Sergey Kuznetsov <kuzzz99@gmail.com>

src/test/jtx/impl/AMM.cpp

@@ -443,7 +443,7 @@ AMM::deposit(
     // If including asset1In and asset2In or tokens as
     // deposit min amounts then must set the flags
     // explicitly instead of relying on this logic.
-    if (!(jvFlags & tfDepositSubTx))
+    if ((jvFlags & tfDepositSubTx) == 0u)
     {
         if (tokens && !asset1In)
         {
@@ -573,7 +573,7 @@ AMM::withdraw(
     std::uint32_t jvFlags = 0;
     if (flags)
         jvFlags = *flags;
-    if (!(jvFlags & tfWithdrawSubTx))
+    if ((jvFlags & tfWithdrawSubTx) == 0u)
     {
         if (tokens && !asset1Out)
         {

src/test/jtx/impl/AMMTest.cpp

@@ -149,13 +149,13 @@ AMMTestBase::testAMM(std::function<void(jtx::AMM&, jtx::Env&)> const& cb, TestAM
 }
 
 XRPAmount
-AMMTest::reserve(jtx::Env& env, std::uint32_t count) const
+AMMTest::reserve(jtx::Env& env, std::uint32_t count)
 {
     return env.current()->fees().accountReserve(count);
 }
 
 XRPAmount
-AMMTest::ammCrtFee(jtx::Env& env) const
+AMMTest::ammCrtFee(jtx::Env& env)
 {
     return env.current()->fees().increment;
 }

src/test/jtx/impl/Env.cpp

@@ -76,7 +76,7 @@ Env::AppBundle::~AppBundle()
     client.reset();
     // Make sure all jobs finish, otherwise tests
     // might not get the coverage they expect.
-    if (app)
+    if (app != nullptr)
     {
         app->getJobQueue().rendezvous();
         app->signalStop("~AppBundle");
@@ -218,6 +218,7 @@ Env::balance(Account const& account, MPTIssue const& mptIssue) const
 }
 
 PrettyAmount
+// NOLINTNEXTLINE(readability-convert-member-functions-to-static)
 Env::balance(Account const& account, Asset const& asset) const
 {
     return std::visit([&](auto const& issue) { return balance(account, issue); }, asset.value());
@@ -468,7 +469,7 @@ Env::postconditions(
         // we didn't get the expected result.
         return;
     }
-    if (trace_)
+    if (trace_ != 0)
     {
         if (trace_ > 0)
             --trace_;

src/test/jtx/impl/Oracle.cpp

@@ -258,7 +258,7 @@ Oracle::set(UpdateArg const& arg)
             return s;
         assert(s.size() <= 20);
         // anything else must be 160-bit hex string
-        return strHex(s).append(40 - s.size() * 2, '0');
+        return strHex(s).append(40 - (s.size() * 2), '0');
     };
     for (auto const& data : arg.series)
     {

src/test/jtx/impl/mpt.cpp

@@ -370,7 +370,7 @@ MPTTester::set(MPTSet const& arg)
          .metadata = arg.metadata,
          .delegate = arg.delegate,
          .domainID = arg.domainID});
-    if (submit(arg, jv) == tesSUCCESS && (arg.flags.value_or(0) || arg.mutableFlags))
+    if (submit(arg, jv) == tesSUCCESS && ((arg.flags.value_or(0) != 0u) || arg.mutableFlags))
     {
         auto require = [&](std::optional<Account> const& holder, bool unchanged) {
             auto flags = getFlags(holder);

src/test/jtx/impl/multisign.cpp

@@ -83,7 +83,7 @@ msig::operator()(Env& env, JTx& jt) const
             jo[sfTxnSignature.getJsonName()] = strHex(Slice{sig.data(), sig.size()});
         }
     };
-    if (!subField)
+    if (subField == nullptr)
     {
         jt.mainSigners.emplace_back(callback);
     }

src/test/jtx/impl/offer.cpp

@@ -17,7 +17,7 @@ offer(
     jv[jss::Account] = account.human();
     jv[jss::TakerPays] = takerPays.getJson(JsonOptions::none);
     jv[jss::TakerGets] = takerGets.getJson(JsonOptions::none);
-    if (flags)
+    if (flags != 0u)
         jv[jss::Flags] = flags;
     jv[jss::TransactionType] = jss::OfferCreate;
     return jv;

src/test/jtx/impl/sig.cpp

@@ -10,7 +10,7 @@ sig::operator()(Env&, JTx& jt) const
 {
     if (!manual_)
         return;
-    if (!subField_)
+    if (subField_ == nullptr)
         jt.fill_sig = false;
     if (account_)
     {
@@ -22,7 +22,7 @@ sig::operator()(Env&, JTx& jt) const
 
             jtx::sign(jtx.jv, account, sigObject);
         };
-        if (!subField_)
+        if (subField_ == nullptr)
         {
             jt.mainSigners.emplace_back(callback);
         }