Replace Catch2's runner with the Catch3 runner

Catch3 keeps Catch2's API for writing tests (test cases, sections,
assertions, matchers, generators, listeners, benchmarks) and replaces its
session, command line and reporters with a runner of its own.

The runner starts the test binary again as worker processes that take the
next test when they are free. A crash, an exit or a hang ends one test, not
the run. On top of that it adds:

- retries that tell deterministic, flaky and order-dependent failures
  apart, and a bisection that names the test leaving state behind;
- a history of verdicts and durations, kept under a file lock, that drives
  automatic quarantine, adaptive time limits, predictive ordering,
  incremental runs, failure replay and analytics;
- selection by change, past failure or prediction, dependency closure,
  and sharding by a stable hash or by recorded durations;
- tags for serial and isolated tests, shared resources, dependencies,
  time limits and retries;
- a failure category, a signature, an analysis and a replay command for
  every failure;
- console, JUnit XML (with flakyFailure and rerunFailure), JSON and Chrome
  trace reports, and a versioned discovery listing (--list=json);
- a temporary directory per test (TMPDIR, TMP, TEMP and
  TestTemporaryDirectory());
- Bazel's test environment: XML output file, test filter, sharding, seed,
  premature exit file and undeclared outputs.

The command line is parsed by a hand-written, typed parser. Catch::Session
remains as a thin facade over the runner for custom main functions.

The result model in Progmasoft/Catch3/Results.hpp was rewritten around
tests and attempts, and the JUnit writer now writes it. The property
engine's example database is updated under a file lock with an atomic
rename, so parallel workers can write it at the same time.

Removed: Clara, the command-line and reporter-spec parsers, every reporter
and CATCH_REGISTER_REPORTER, listing, text flow, console colour and width,
the JSON and XML writers, sharding in the test registry, approval tests and
their baselines, Conan packaging, and the unused third_party/clara.hpp.
Listeners keep working; reporters' list and skip events are gone.

The Catch2 library is now compiled as C++20; code that includes only
Catch2's headers still needs C++14. Duplicate test cases are still refused
at start-up. Version 0.3.0.

ExtraTests now turn exceptions off for clang-cl with MSVC-style options,
which -fno-exceptions did not do.

1 files changed, 56 insertions, 15 deletions

diff --git a/src/Progmasoft/PropertyEngine.cpp b/src/Progmasoft/PropertyEngine.cpp
index c42b235f..571a5ac3 100644
--- a/src/Progmasoft/PropertyEngine.cpp
+++ b/src/Progmasoft/PropertyEngine.cpp
@@ -2,7 +2,12 @@
 // SPDX-License-Identifier: MPL-2.0 WITH AdditionRef-Progmasoft-Exception-1.1
 #include <Progmasoft/Catch3/Strategy/Engine.hpp>
 
+#include <Progmasoft/Runner/Files.hpp>
+
 #include <algorithm>
+#include <atomic>
+#include <chrono>
+#include <cstdio>
 #include <cstdlib>
 #include <filesystem>
 #include <fstream>
@@ -10,6 +15,7 @@
 #include <sstream>
 #include <string>
 #include <system_error>
+#include <thread>
 #include <utility>
 
 namespace Progmasoft::Catch3::Detail
@@ -75,24 +81,53 @@ namespace Progmasoft::Catch3::Detail
                 return tokens;
             }
 
+            /// Changes the stored tokens under a lock: the file is read
+            /// again, `change` edits what it holds, and the result replaces
+            /// the file in one rename. Workers of a parallel run, retries and
+            /// repeats of one property may write at the same time; none of
+            /// them loses what another stored.
+            template<typename Change>
             void
-            Save(const std::vector<std::string> &tokens) const
+            Update(Change change) const
             {
                 if (file_.empty())
                 {
                     return;
                 }
                 std::error_code error;
+                std::filesystem::create_directories(file_.parent_path(), error);
+                const Runner::FileLock lock(file_, std::chrono::seconds(2),
+                                            std::chrono::seconds(10));
+                auto tokens = Load();
+                change(tokens);
                 if (tokens.empty())
                 {
                     std::filesystem::remove(file_, error);
                     return;
                 }
-                std::filesystem::create_directories(file_.parent_path(), error);
-                std::ofstream output(file_, std::ios::trunc);
-                for (const auto &token : tokens)
+                const auto temporary = std::filesystem::path(
+                    file_.string() + "." + Runner::UniqueName() + ".tmp");
+                {
+                    std::ofstream output(temporary,
+                                         std::ios::binary | std::ios::trunc);
+                    for (const auto &token : tokens)
+                    {
+                        output << token << '\n';
+                    }
+                    if (!output)
+                    {
+                        output.close();
+                        std::filesystem::remove(temporary, error);
+                        return;
+                    }
+                }
+                // rename replaces the target atomically on every platform
+                // the library supports, so a reader sees the old or the new
+                // file, never a half-written one.
+                std::filesystem::rename(temporary, file_, error);
+                if (error)
                 {
-                    output << token << '\n';
+                    std::filesystem::remove(temporary, error);
                 }
             }
 
@@ -243,8 +278,7 @@ namespace Progmasoft::Catch3::Detail
             std::optional<PropertyResult>
             ReplayDatabase()
             {
-                auto tokens = database_.Load();
-                std::vector<std::string> kept;
+                const auto tokens = database_.Load();
                 for (const auto &token : tokens)
                 {
                     const auto decoded = DecodeChoices(token);
@@ -265,7 +299,14 @@ namespace Progmasoft::Catch3::Detail
                 }
                 if (!tokens.empty())
                 {
-                    database_.Save(kept);
+                    // Only the examples checked here are dropped; another
+                    // process may have stored new ones meanwhile.
+                    database_.Update([&](std::vector<std::string> &stored) {
+                        std::erase_if(stored, [&](const std::string &token) {
+                            return std::find(tokens.begin(), tokens.end(), token)
+                                   != tokens.end();
+                        });
+                    });
                 }
                 return std::nullopt;
             }
@@ -474,13 +515,13 @@ namespace Progmasoft::Catch3::Detail
                 failure.Replay = EncodeChoices(size, failing.Choices);
                 failure.Notes = std::move(failing.Outcome.Record.Notes);
 
-                auto stored = database_.Load();
-                if (std::find(stored.begin(), stored.end(), failure.Replay)
-                    == stored.end())
-                {
-                    stored.insert(stored.begin(), failure.Replay);
-                    database_.Save(stored);
-                }
+                database_.Update([&](std::vector<std::string> &stored) {
+                    if (std::find(stored.begin(), stored.end(), failure.Replay)
+                        == stored.end())
+                    {
+                        stored.insert(stored.begin(), failure.Replay);
+                    }
+                });
 
                 PropertyResult result;
                 result.Status = PropertyStatus::kFailed;