Fix the CI failures of the runner and test its planner, options and analysis

ExtraTests X21 and X27 defined their listeners at namespace scope, which
clang rejects under -Wweak-vtables with -Werror on Linux and macOS; they
are now in anonymous namespaces.

After a fatal signal Catch2 closes the open sections itself, so on POSIX a
crash was reported outside the section it happened in. The scheduler now
ignores section ends that follow a fatal condition.

New unit tests cover the planner (every selection, dependency closure and
cycles, hash and duration shards, incremental runs, learned time limits,
ordering, retries, quarantine and replay), every command-line option and
its errors, and the failure analysis (history classes, signature groups,
crash and hang locations, changed files, replay commands).
Catalog::FromEntries builds a catalog without a test registry so the
planner can be tested on its own.

8 files changed, 1302 insertions, 0 deletions

diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 14f2ed56..e57ad94a 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -157,6 +157,9 @@ add_executable(ProgmasoftSelfTest
   Progmasoft/Results.tests.cpp
   Progmasoft/Runner.tests.cpp
   Progmasoft/RunnerUnits.tests.cpp
+  Progmasoft/RunnerPlanner.tests.cpp
+  Progmasoft/RunnerOptions.tests.cpp
+  Progmasoft/RunnerAnalysis.tests.cpp
   Progmasoft/Snapshot.tests.cpp
   Progmasoft/Stateful.tests.cpp
   Progmasoft/Strategy.tests.cpp
diff --git a/tests/ExtraTests/X21-PartialTestCaseEvents.cpp b/tests/ExtraTests/X21-PartialTestCaseEvents.cpp
index c55f6c2b..99002822 100644
--- a/tests/ExtraTests/X21-PartialTestCaseEvents.cpp
+++ b/tests/ExtraTests/X21-PartialTestCaseEvents.cpp
@@ -28,6 +28,7 @@
 using Catch::TestCaseInfo;
 using Catch::TestCaseStats;
 
+namespace {
 class PartialListener : public Catch::EventListenerBase {
 public:
     using EventListenerBase::EventListenerBase;
@@ -58,6 +59,7 @@ public:
 private:
     std::string m_events;
 };
+} // namespace
 
 CATCH_REGISTER_LISTENER(PartialListener)
 
diff --git a/tests/ExtraTests/X27-CapturedStdoutInTestCaseEvents.cpp b/tests/ExtraTests/X27-CapturedStdoutInTestCaseEvents.cpp
index 7ceebcee..20b39d78 100644
--- a/tests/ExtraTests/X27-CapturedStdoutInTestCaseEvents.cpp
+++ b/tests/ExtraTests/X27-CapturedStdoutInTestCaseEvents.cpp
@@ -27,6 +27,7 @@
 #include <iostream>
 #include <string>
 
+namespace {
 class TestListener : public Catch::EventListenerBase {
     std::string stdOutString( uint64_t iter ){
         return "stdout " + std::to_string( iter ) + '\n';
@@ -66,6 +67,7 @@ public:
         std::cerr << "X27 - listener saw " << m_errors << " error(s)\n";
     }
 };
+} // namespace
 
 CATCH_REGISTER_LISTENER( TestListener )
 
diff --git a/tests/Progmasoft/BUILD.bazel b/tests/Progmasoft/BUILD.bazel
index 296fd5f1..06df86d6 100644
--- a/tests/Progmasoft/BUILD.bazel
+++ b/tests/Progmasoft/BUILD.bazel
@@ -13,6 +13,9 @@ cc_test(
         "Results.tests.cpp",
         "Runner.tests.cpp",
         "RunnerUnits.tests.cpp",
+        "RunnerPlanner.tests.cpp",
+        "RunnerOptions.tests.cpp",
+        "RunnerAnalysis.tests.cpp",
         "Snapshot.tests.cpp",
         "Stateful.tests.cpp",
         "Strategy.tests.cpp",
diff --git a/tests/Progmasoft/RunnerAnalysis.tests.cpp b/tests/Progmasoft/RunnerAnalysis.tests.cpp
new file mode 100644
index 00000000..453fa671
--- /dev/null
+++ b/tests/Progmasoft/RunnerAnalysis.tests.cpp
@@ -0,0 +1,321 @@
+// Copyright (c) 2026 Progmasoft.
+// SPDX-License-Identifier: MPL-2.0 WITH AdditionRef-Progmasoft-Exception-1.1
+
+// What the runner writes down about a failure: how it relates to earlier
+// runs and to other failures, where it stopped, what changed and how to
+// run it again.
+
+#include <Progmasoft/Runner/Analysis.hpp>
+#include <Progmasoft/Runner/Files.hpp>
+#include <Progmasoft/Runner/History.hpp>
+
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/matchers/catch_matchers_string.hpp>
+#include <catch2/matchers/catch_matchers_vector.hpp>
+
+#include <filesystem>
+#include <string>
+#include <vector>
+
+namespace
+{
+    namespace Runner = Progmasoft::Catch3::Runner;
+    using Catch::Matchers::ContainsSubstring;
+    using Progmasoft::Catch3::AssertionRecord;
+    using Progmasoft::Catch3::Attempt;
+    using Progmasoft::Catch3::FailureCategory;
+    using Progmasoft::Catch3::FailureHistory;
+    using Progmasoft::Catch3::Outcome;
+    using Progmasoft::Catch3::RunResult;
+    using Progmasoft::Catch3::SectionRecord;
+    using Progmasoft::Catch3::TestResult;
+
+    /// A directory of its own, removed at the end of the test.
+    class Scratch final
+    {
+    public:
+        Scratch()
+        {
+            std::error_code error;
+            path_ = std::filesystem::temp_directory_path(error) /
+                    ("catch3-analysis-" + Runner::UniqueName());
+            std::filesystem::create_directories(path_, error);
+        }
+        Scratch(const Scratch &) = delete;
+        Scratch &
+        operator=(const Scratch &) = delete;
+        ~Scratch()
+        {
+            std::error_code error;
+            std::filesystem::remove_all(path_, error);
+        }
+
+        [[nodiscard]] const std::filesystem::path &
+        Path() const noexcept
+        {
+            return path_;
+        }
+
+    private:
+        std::filesystem::path path_;
+    };
+
+    /// A test that failed one assertion.
+    TestResult
+    Failed(const std::string &name,
+           const std::string &message = "wrong",
+           std::size_t line = 10)
+    {
+        TestResult test;
+        test.id = name;
+        test.name = name;
+        test.file = "src/test.cpp";
+        test.line = 1;
+        test.outcome = Outcome::kFailed;
+        test.category = FailureCategory::kAssertion;
+        Attempt attempt;
+        attempt.outcome = Outcome::kFailed;
+        attempt.category = FailureCategory::kAssertion;
+        attempt.seed = 7;
+        AssertionRecord assertion;
+        assertion.file = "src/test.cpp";
+        assertion.line = line;
+        assertion.expression = "a == b";
+        assertion.message = message;
+        attempt.assertions.push_back(assertion);
+        test.attempts.push_back(attempt);
+        return test;
+    }
+
+    TestResult
+    Passed(const std::string &name)
+    {
+        TestResult test;
+        test.id = name;
+        test.name = name;
+        test.outcome = Outcome::kPassed;
+        Attempt attempt;
+        attempt.outcome = Outcome::kPassed;
+        test.attempts.push_back(attempt);
+        return test;
+    }
+
+    /// Commits runs of `tests` to a history, the last commit last.
+    Runner::History
+    HistoryOf(const std::filesystem::path &file,
+              const std::vector<std::vector<TestResult>> &runs)
+    {
+        Runner::History history;
+        int number = 0;
+        for (const auto &tests : runs)
+        {
+            RunResult run;
+            run.tests = tests;
+            for (auto &test : run.tests)
+            {
+                // As the runner does before it commits a run.
+                for (const auto &attempt : test.attempts)
+                {
+                    if (Progmasoft::Catch3::IsFailure(attempt.outcome))
+                    {
+                        test.signature = Runner::FailureSignature(attempt);
+                        break;
+                    }
+                }
+            }
+            Runner::RunRecord record;
+            record.commit = "commit" + std::to_string(++number) + "0123456789";
+            auto committed =
+                Runner::History::Commit(file, run, record, {}, {});
+            REQUIRE(committed);
+            history = *committed;
+        }
+        return history;
+    }
+
+    std::string
+    Findings(const TestResult &test)
+    {
+        std::string text;
+        for (const auto &finding : test.analysis)
+        {
+            text += finding + "\n";
+        }
+        return text;
+    }
+} // namespace
+
+TEST_CASE("A failure is placed in the test's history",
+          "[progmasoft][runner][analysis]")
+{
+    const Scratch scratch;
+    const auto file = Runner::HistoryFile(scratch.Path(), "classes");
+    auto flaky = Passed("flaky");
+    flaky.flaky = true;
+    flaky.attempts.front().outcome = Outcome::kFailed;
+    const auto history = HistoryOf(
+        file,
+        {{Passed("fresh"), Failed("stuck", "first"), Passed("wobbly")},
+         {Passed("fresh"), Failed("stuck", "first"), flaky}});
+
+    RunResult run;
+    run.tests = {Failed("unknown"),
+                 Failed("fresh", "one"),
+                 Failed("stuck", "second", 20),
+                 Failed("flaky", "three", 30)};
+    Runner::AnalysisInputs inputs;
+    inputs.history = &history;
+    inputs.program = "tests";
+    Runner::Analyze(run, inputs);
+
+    CHECK(run.tests[0].history == FailureHistory::kUnknown);
+
+    CHECK(run.tests[1].history == FailureHistory::kNew);
+    CHECK_THAT(Findings(run.tests[1]),
+               ContainsSubstring("new failure after 2 passing run(s); it "
+                                 "last passed at commit commit201234"));
+
+    CHECK(run.tests[2].history == FailureHistory::kPersistent);
+    CHECK_THAT(Findings(run.tests[2]),
+               ContainsSubstring("persistent: failed in the last 2 run(s), "
+                                 "but differently last time"));
+
+    CHECK(run.tests[3].history == FailureHistory::kIntermittent);
+    CHECK_THAT(Findings(run.tests[3]),
+               ContainsSubstring("intermittent: 1 flaky result(s)"));
+}
+
+TEST_CASE("Failures with one signature are named together",
+          "[progmasoft][runner][analysis]")
+{
+    RunResult run;
+    for (const char *name : {"a", "b", "c", "d", "e"})
+    {
+        // Numbers in the message do not split the group.
+        run.tests.push_back(Failed(
+            name,
+            "connection refused after " +
+                std::to_string((run.tests.size() + 1) * 100) + " ms"));
+    }
+    run.tests.push_back(Failed("elsewhere", "other", 99));
+    Runner::AnalysisInputs inputs;
+    inputs.program = "tests";
+    Runner::Analyze(run, inputs);
+
+    CHECK(run.tests[0].signature == run.tests[4].signature);
+    CHECK(run.tests[0].signature != run.tests[5].signature);
+    CHECK_THAT(Findings(run.tests[0]),
+               ContainsSubstring("fails the same way as 'b', 'c', 'd' and 1 "
+                                 "more: probably one cause"));
+    CHECK_THAT(Findings(run.tests[5]),
+               !ContainsSubstring("fails the same way"));
+}
+
+TEST_CASE("A crash and a hang say where they stopped",
+          "[progmasoft][runner][analysis]")
+{
+    SectionRecord outer;
+    outer.name = "outer";
+    outer.depth = 0;
+    outer.durationMicroseconds = -1;
+    SectionRecord done;
+    done.name = "done";
+    done.depth = 1;
+    done.durationMicroseconds = 5;
+    SectionRecord inner;
+    inner.name = "inner";
+    inner.depth = 1;
+    inner.durationMicroseconds = -1;
+
+    TestResult crash = Failed("crash");
+    crash.outcome = Outcome::kCrashed;
+    Attempt &crashed = crash.attempts.front();
+    crashed.outcome = Outcome::kCrashed;
+    crashed.category = FailureCategory::kCrash;
+    crashed.assertions.clear();
+    crashed.exitDescription = "signal 11 (SIGSEGV)";
+    crashed.lastLocation = "src/test.cpp:44";
+    crashed.sections = {outer, done, inner};
+
+    TestResult hang = Failed("hang");
+    hang.outcome = Outcome::kTimedOut;
+    hang.predictedDurationMicroseconds = 200000;
+    Attempt &hung = hang.attempts.front();
+    hung.outcome = Outcome::kTimedOut;
+    hung.category = FailureCategory::kTimeout;
+    hung.assertions.clear();
+    hung.durationMicroseconds = 5000000;
+    hung.lastLocation = "src/test.cpp:50";
+    hung.sections = {outer};
+
+    RunResult run;
+    run.tests = {crash, hang};
+    Runner::AnalysisInputs inputs;
+    inputs.program = "tests";
+    Runner::Analyze(run, inputs);
+
+    CHECK_THAT(Findings(run.tests[0]),
+               ContainsSubstring("crashed (signal 11 (SIGSEGV)) after the "
+                                 "assertion at src/test.cpp:44, in section "
+                                 "outer / inner"));
+    CHECK_THAT(Findings(run.tests[1]),
+               ContainsSubstring("stopped after 5.0 s"));
+    CHECK_THAT(Findings(run.tests[1]),
+               ContainsSubstring("it was in section outer"));
+    CHECK_THAT(Findings(run.tests[1]),
+               ContainsSubstring("last assertion started at src/test.cpp:50"));
+    // Two crashes in different places are different failures.
+    CHECK(run.tests[0].signature != run.tests[1].signature);
+}
+
+TEST_CASE("A failure names the changed files it touches",
+          "[progmasoft][runner][analysis]")
+{
+    const Scratch scratch;
+    Runner::Changes changes;
+    changes.root = scratch.Path();
+    changes.files = {scratch.Path() / "src" / "test.cpp",
+                     scratch.Path() / "src" / "helper.hpp"};
+    TestResult test = Failed("touched");
+    AssertionRecord inHelper;
+    inHelper.file = "src/helper.hpp";
+    inHelper.line = 3;
+    inHelper.passed = false;
+    test.attempts.front().assertions.push_back(inHelper);
+    test.attempts.front().temporaryDirectory = "/tmp/kept";
+
+    RunResult run;
+    run.tests = {test};
+    Runner::AnalysisInputs inputs;
+    inputs.changes = &changes;
+    inputs.changesSince = "main";
+    inputs.program = "tests";
+    Runner::Analyze(run, inputs);
+
+    const auto findings = Findings(run.tests[0]);
+    CHECK_THAT(findings, ContainsSubstring("changed since main: src/test.cpp"));
+    CHECK_THAT(findings, ContainsSubstring("changed since main: src/helper.hpp"));
+    CHECK_THAT(findings,
+               ContainsSubstring("its temporary files are kept in /tmp/kept"));
+}
+
+TEST_CASE("Every failure gets a command that runs it again",
+          "[progmasoft][runner][analysis]")
+{
+    RunResult run;
+    run.tests = {Failed("plain, with [specials]"), Failed("after another"),
+                 Passed("fine")};
+    run.tests[1].attempts.front().precededBy = {"polluter"};
+    Runner::AnalysisInputs inputs;
+    inputs.program = "build dir/tests";
+    Runner::Analyze(run, inputs);
+
+    CHECK_THAT(run.tests[0].replayCommand,
+               ContainsSubstring("plain\\\\, with \\\\[specials\\\\]"));
+    CHECK_THAT(run.tests[0].replayCommand, ContainsSubstring("--seed=7"));
+    CHECK_THAT(run.tests[0].replayCommand, ContainsSubstring("build dir/tests"));
+    // A failure that needed other tests first is replayed with them.
+    CHECK_THAT(run.tests[1].replayCommand, ContainsSubstring("--replay"));
+    CHECK(run.tests[2].replayCommand.empty());
+    CHECK(run.tests[2].analysis.empty());
+}
diff --git a/tests/Progmasoft/RunnerOptions.tests.cpp b/tests/Progmasoft/RunnerOptions.tests.cpp
new file mode 100644
index 00000000..2ad8c0b7
--- /dev/null
+++ b/tests/Progmasoft/RunnerOptions.tests.cpp
@@ -0,0 +1,369 @@
+// Copyright (c) 2026 Progmasoft.
+// SPDX-License-Identifier: MPL-2.0 WITH AdditionRef-Progmasoft-Exception-1.1
+
+// Every option of the runner's command line: how it is spelled, what it
+// sets and how a wrong value is explained.
+
+#include <Progmasoft/Runner/Files.hpp>
+#include <Progmasoft/Runner/Options.hpp>
+
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/generators/catch_generators.hpp>
+#include <catch2/matchers/catch_matchers_string.hpp>
+
+#include <chrono>
+#include <filesystem>
+#include <fstream>
+#include <string>
+#include <vector>
+
+namespace
+{
+    namespace Runner = Progmasoft::Catch3::Runner;
+    using Catch::Matchers::ContainsSubstring;
+    using std::chrono::milliseconds;
+
+    Runner::Options
+    Parse(const std::vector<std::string> &arguments)
+    {
+        auto options = Runner::ParseOptions(arguments);
+        INFO((options ? std::string{} : options.GetError().Message()));
+        REQUIRE(options);
+        return *options;
+    }
+
+    std::string
+    ParseError(const std::vector<std::string> &arguments)
+    {
+        auto options = Runner::ParseOptions(arguments);
+        REQUIRE_FALSE(options);
+        return options.GetError().Message();
+    }
+} // namespace
+
+TEST_CASE("Options have their documented defaults",
+          "[progmasoft][runner][options]")
+{
+    const auto options = Parse({});
+    CHECK(options.mode == Runner::Mode::kRun);
+    CHECK(options.selection == Runner::Selection::kAll);
+    CHECK(options.order == Runner::Order::kPriority);
+    CHECK(options.retryMode == Runner::RetryMode::kAuto);
+    CHECK(options.retries == 2);
+    CHECK(options.repeat == 1);
+    CHECK(options.failFast == 0);
+    CHECK(options.jobs == 0);
+    CHECK(options.shard.index == 0);
+    CHECK(options.shard.count == 1);
+    CHECK_FALSE(options.timeoutGiven);
+    CHECK(options.adaptiveTimeout);
+    CHECK(options.bisectOrder);
+    CHECK(options.historyEnabled);
+    CHECK(options.quarantine == Runner::QuarantineMode::kAuto);
+    CHECK(options.verbosity == Runner::Verbosity::kNormal);
+    CHECK(options.color == Runner::ColorMode::kAuto);
+    CHECK(options.benchmarkSamples == 100);
+    CHECK(options.benchmarkResamples == 100000);
+    CHECK(options.benchmarkConfidenceInterval == 0.95);
+    CHECK(options.benchmarkWarmupTime == milliseconds{100});
+    CHECK(options.testSpecs.empty());
+}
+
+TEST_CASE("A value can follow an option in every accepted spelling",
+          "[progmasoft][runner][options]")
+{
+    const std::vector<std::string> arguments = GENERATE(
+        std::vector<std::string>{"--jobs=4"},
+        std::vector<std::string>{"--jobs", "4"},
+        std::vector<std::string>{"-j4"},
+        std::vector<std::string>{"-j=4"},
+        std::vector<std::string>{"-j", "4"});
+    CAPTURE(arguments);
+    CHECK(Parse(arguments).jobs == 4);
+}
+
+TEST_CASE("Switches set what they say", "[progmasoft][runner][options]")
+{
+    CHECK(Parse({"--incremental"}).incremental);
+    CHECK(Parse({"--filenames-as-tags"}).filenamesAsTags);
+    CHECK(Parse({"-#"}).filenamesAsTags);
+    CHECK(Parse({"--in-process"}).inProcess);
+    CHECK(Parse({"--isolate"}).isolate);
+    CHECK_FALSE(Parse({"--no-adaptive-timeout"}).adaptiveTimeout);
+    CHECK_FALSE(Parse({"--no-bisect"}).bisectOrder);
+    CHECK(Parse({"--success"}).includeSuccessful);
+    CHECK(Parse({"-s"}).includeSuccessful);
+    CHECK(Parse({"--no-throw"}).noThrow);
+    CHECK(Parse({"-e"}).noThrow);
+    CHECK(Parse({"--allow-no-tests"}).allowNoTests);
+    CHECK(Parse({"--skip-benchmarks"}).skipBenchmarks);
+    CHECK(Parse({"--benchmark-no-analysis"}).benchmarkNoAnalysis);
+    CHECK_FALSE(Parse({"--no-history"}).historyEnabled);
+    CHECK(Parse({"--replay"}).replayFailures);
+    CHECK(Parse({"--verbose"}).verbosity == Runner::Verbosity::kVerbose);
+    CHECK(Parse({"-q"}).verbosity == Runner::Verbosity::kQuiet);
+
+    // A debugger needs the test in this process.
+    const auto debugging = Parse({"-b"});
+    CHECK(debugging.breakIntoDebugger);
+    CHECK(debugging.inProcess);
+}
+
+TEST_CASE("Modes are chosen by their options", "[progmasoft][runner][options]")
+{
+    CHECK(Parse({"--help"}).mode == Runner::Mode::kHelp);
+    CHECK(Parse({"-h"}).mode == Runner::Mode::kHelp);
+    CHECK(Parse({"--version"}).mode == Runner::Mode::kVersion);
+    CHECK(Parse({"--list-tags"}).mode == Runner::Mode::kListTags);
+    CHECK(Parse({"-t"}).mode == Runner::Mode::kListTags);
+    CHECK(Parse({"--catch3-worker"}).mode == Runner::Mode::kWorker);
+
+    const auto text = Parse({"-l"});
+    CHECK(text.mode == Runner::Mode::kListTests);
+    CHECK(text.listFormat == Runner::ListFormat::kText);
+    CHECK(Parse({"--list=names"}).listFormat == Runner::ListFormat::kNames);
+    CHECK(Parse({"--list=json"}).listFormat == Runner::ListFormat::kJson);
+
+    const auto analytics = Parse({"--analytics"});
+    CHECK(analytics.mode == Runner::Mode::kAnalytics);
+    CHECK_FALSE(analytics.analyticsJson);
+    CHECK(Parse({"--analytics=json"}).analyticsJson);
+}
+
+TEST_CASE("Choices accept their names and nothing else",
+          "[progmasoft][runner][options]")
+{
+    CHECK(Parse({"--select=all"}).selection == Runner::Selection::kAll);
+    CHECK(Parse({"--select=failed"}).selection == Runner::Selection::kFailed);
+    CHECK(Parse({"--select=changed"}).selection == Runner::Selection::kChanged);
+    CHECK(Parse({"--select=new"}).selection == Runner::Selection::kNew);
+    CHECK(Parse({"--select=smart"}).selection == Runner::Selection::kSmart);
+    CHECK(Parse({"--order=name"}).order == Runner::Order::kName);
+    CHECK(Parse({"--order=random"}).order == Runner::Order::kRandom);
+    CHECK(Parse({"--order=priority"}).order == Runner::Order::kPriority);
+    CHECK(Parse({"--quarantine=report"}).quarantine ==
+          Runner::QuarantineMode::kReport);
+    CHECK(Parse({"--quarantine=off"}).quarantine ==
+          Runner::QuarantineMode::kOff);
+    CHECK(Parse({"--color=always"}).color == Runner::ColorMode::kAlways);
+    CHECK(Parse({"--color=never"}).color == Runner::ColorMode::kNever);
+
+    CHECK_THAT(ParseError({"--select=some"}),
+               ContainsSubstring("all, failed, changed, new, smart"));
+    CHECK_THAT(ParseError({"--quarantine=maybe"}),
+               ContainsSubstring("auto, report, off"));
+    CHECK_THAT(ParseError({"--color=blue"}),
+               ContainsSubstring("auto, always, never"));
+    CHECK_THAT(ParseError({"--list=xml"}),
+               ContainsSubstring("text, names, json"));
+    CHECK_THAT(ParseError({"--analytics=xml"}), ContainsSubstring("json"));
+}
+
+TEST_CASE("Numbers are checked", "[progmasoft][runner][options]")
+{
+    CHECK(Parse({"--repeat=3"}).repeat == 3);
+    CHECK(Parse({"-a"}).failFast == 1);
+    CHECK(Parse({"--slowest"}).slowest == 10);
+    CHECK(Parse({"--slowest=3"}).slowest == 3);
+    CHECK(Parse({"--benchmark-samples=7"}).benchmarkSamples == 7);
+    CHECK(Parse({"--benchmark-resamples=9"}).benchmarkResamples == 9);
+    CHECK(Parse({"--benchmark-confidence-interval=0.5"})
+              .benchmarkConfidenceInterval == 0.5);
+    CHECK(Parse({"--benchmark-warmup-time=250"}).benchmarkWarmupTime ==
+          milliseconds{250});
+
+    const auto unlimited = Parse({"--timeout=0"});
+    CHECK(unlimited.timeoutGiven);
+    CHECK(unlimited.timeout == milliseconds{0});
+
+    const auto retried = Parse({"--retries=auto"});
+    CHECK(retried.retryMode == Runner::RetryMode::kAuto);
+    const auto off = Parse({"--retries=off"});
+    CHECK(off.retryMode == Runner::RetryMode::kOff);
+    CHECK(off.retries == 0);
+
+    const auto random = Parse({"--seed=5", "--seed=random"});
+    CHECK_FALSE(random.seedGiven);
+
+    CHECK_THAT(ParseError({"--repeat=0"}), ContainsSubstring("at least 1"));
+    CHECK_THAT(ParseError({"--fail-fast=0"}), ContainsSubstring("at least 1"));
+    CHECK_THAT(ParseError({"--slowest=0"}), ContainsSubstring("at least 1"));
+    CHECK_THAT(ParseError({"--retries=-1"}), ContainsSubstring("whole number"));
+    CHECK_THAT(ParseError({"--timeout=soon"}), ContainsSubstring("seconds"));
+    CHECK_THAT(ParseError({"--timeout=-2"}), ContainsSubstring("seconds"));
+    CHECK_THAT(ParseError({"--benchmark-confidence-interval=1"}),
+               ContainsSubstring("--benchmark-confidence-interval"));
+    CHECK_THAT(ParseError({"--benchmark-samples=0"}),
+               ContainsSubstring("at least 1"));
+    CHECK_THAT(ParseError({"--seed=-1"}), ContainsSubstring("--seed"));
+    CHECK_THAT(ParseError({"--generator-index=x"}),
+               ContainsSubstring("index or *"));
+    CHECK_THAT(ParseError({"--path-filter=g:x"}),
+               ContainsSubstring("generator index or *"));
+}
+
+TEST_CASE("Shards are an index below a count", "[progmasoft][runner][options]")
+{
+    const auto last = Parse({"--shard=3/4"});
+    CHECK(last.shard.index == 3);
+    CHECK(last.shard.count == 4);
+    const std::string wrong = GENERATE("4/4", "1", "/2", "1/", "0/0", "a/b");
+    CAPTURE(wrong);
+    CHECK_THAT(ParseError({"--shard=" + wrong}), ContainsSubstring("INDEX/COUNT"));
+}
+
+TEST_CASE("Warnings are named", "[progmasoft][runner][options]")
+{
+    CHECK(Parse({"--warn=no-assertions"}).warnNoAssertions);
+    CHECK(Parse({"-w", "NoAssertions"}).warnNoAssertions);
+    CHECK(Parse({"--warn=unmatched-specs"}).warnUnmatchedSpecs);
+    CHECK(Parse({"--warn=infinite-generators"}).warnInfiniteGenerators);
+    CHECK_THAT(ParseError({"--warn=everything"}),
+               ContainsSubstring("no-assertions"));
+}
+
+TEST_CASE("Files and directories are taken as written",
+          "[progmasoft][runner][options]")
+{
+    const auto options = Parse({"--junit=out/junit.xml",
+                                "--json",
+                                "out/run.json",
+                                "--trace=out/trace.json",
+                                "--history=cache",
+                                "--shard-durations=last.json",
+                                "--changes-since=main",
+                                "--premature-exit-guard-file=guard"});
+    CHECK(options.junitPath == "out/junit.xml");
+    CHECK(options.jsonPath == "out/run.json");
+    CHECK(options.tracePath == "out/trace.json");
+    CHECK(options.historyDirectory == "cache");
+    CHECK(options.historyEnabled);
+    CHECK(options.shardDurations == "last.json");
+    CHECK(options.changesSince == "main");
+    CHECK(options.exitGuardPath == "guard");
+}
+
+TEST_CASE("Test specs are kept apart from options",
+          "[progmasoft][runner][options]")
+{
+    const auto options =
+        Parse({"name", "[tag]", "~[slow]", "-", "--", "-j", "--x"});
+    CHECK(options.jobs == 0);
+    CHECK(options.testSpecs ==
+          std::vector<std::string>{"name", "[tag]", "~[slow]", "-", "-j", "--x"});
+}
+
+TEST_CASE("An input file names tests exactly", "[progmasoft][runner][options]")
+{
+    std::error_code error;
+    const auto file = std::filesystem::temp_directory_path(error) /
+                      ("catch3-input-" + Runner::UniqueName());
+    std::ofstream(file) << "# a comment\n"
+                           "first test\r\n"
+                           "\n"
+                           "  \"quoted, with a comma\"  \n"
+                           "last*\n";
+    const auto options = Parse({"--input-file=" + file.string()});
+    CHECK(options.testSpecs == std::vector<std::string>{"\"first test\"",
+                                                        ",",
+                                                        "\"quoted, with a comma\"",
+                                                        ",",
+                                                        "\"last*\""});
+    std::filesystem::remove(file, error);
+    CHECK_THAT(ParseError({"-f", file.string()}), ContainsSubstring("cannot read"));
+}
+
+TEST_CASE("Unknown options are refused with a suggestion",
+          "[progmasoft][runner][options]")
+{
+    CHECK_THAT(ParseError({"--sucess"}), ContainsSubstring("did you mean --success?"));
+    CHECK_THAT(ParseError({"--histroy=x"}), ContainsSubstring("did you mean --history?"));
+    CHECK_THAT(ParseError({"-z"}), ContainsSubstring("'-z' is not an option"));
+    // Catch2's reporter options are gone with its reporters.
+    CHECK_THAT(ParseError({"--reporter=junit"}), ContainsSubstring("is not an option"));
+    CHECK_THAT(ParseError({"--isolate=yes"}), ContainsSubstring("takes no value"));
+    CHECK_THAT(ParseError({"--junit"}), ContainsSubstring("--junit=FILE"));
+}
+
+TEST_CASE("The help lists every option", "[progmasoft][runner][options]")
+{
+    const std::string help = Runner::HelpText("tests");
+    CHECK_THAT(help, ContainsSubstring("usage: tests [options] [test specs...]"));
+    for (const char *name : {"--section",       "--generator-index",
+                             "--path-filter",   "--input-file",
+                             "--select",        "--changes-since",
+                             "--incremental",   "--shard",
+                             "--shard-durations", "--filenames-as-tags",
+                             "--jobs",          "--in-process",
+                             "--isolate",       "--timeout",
+                             "--no-adaptive-timeout", "--retries",
+                             "--repeat",        "--fail-fast",
+                             "--order",         "--seed",
+                             "--no-bisect",     "--success",
+                             "--break",         "--no-throw",
+                             "--warn",          "--allow-no-tests",
+                             "--skip-benchmarks", "--benchmark-samples",
+                             "--benchmark-resamples",
+                             "--benchmark-confidence-interval",
+                             "--benchmark-no-analysis",
+                             "--benchmark-warmup-time",
+                             "--history",       "--no-history",
+                             "--quarantine",    "--replay",
+                             "--analytics",     "--verbose",
+                             "--quiet",         "--color",
+                             "--junit",         "--json",
+                             "--trace",         "--premature-exit-guard-file",
+                             "--slowest",       "--list",
+                             "--list-tags",     "--help",
+                             "--version"})
+    {
+        CAPTURE(name);
+        CHECK_THAT(help, ContainsSubstring(name));
+    }
+    // The worker option is internal.
+    CHECK_THAT(help, !ContainsSubstring("--catch3-worker"));
+}
+
+TEST_CASE("A worker gets every option that changes how tests behave",
+          "[progmasoft][runner][options]")
+{
+    const auto options = Parse({"--section=outer",
+                                "--section=inner",
+                                "-p",
+                                "g:1",
+                                "-#",
+                                "-s",
+                                "-e",
+                                "--warn=no-assertions",
+                                "--warn=infinite-generators",
+                                "--skip-benchmarks",
+                                "--benchmark-no-analysis",
+                                "--benchmark-samples=3",
+                                "--benchmark-resamples=4",
+                                "--benchmark-warmup-time=5",
+                                "--benchmark-confidence-interval=0.9",
+                                "--seed=6",
+                                // Runner-side only:
+                                "--jobs=9",
+                                "--junit=x.xml",
+                                "[tag]"});
+    const auto worker = Parse(Runner::WorkerArguments(options));
+    CHECK(worker.mode == Runner::Mode::kWorker);
+    CHECK(worker.sections == options.sections);
+    CHECK(worker.paths == options.paths);
+    CHECK(worker.filenamesAsTags);
+    CHECK(worker.includeSuccessful);
+    CHECK(worker.noThrow);
+    CHECK(worker.warnNoAssertions);
+    CHECK(worker.warnInfiniteGenerators);
+    CHECK(worker.skipBenchmarks);
+    CHECK(worker.benchmarkNoAnalysis);
+    CHECK(worker.benchmarkSamples == 3);
+    CHECK(worker.benchmarkResamples == 4);
+    CHECK(worker.benchmarkWarmupTime == milliseconds{5});
+    CHECK(worker.benchmarkConfidenceInterval == 0.9);
+    CHECK(worker.seed == 6);
+    CHECK(worker.jobs == 0);
+    CHECK(worker.junitPath.empty());
+    CHECK(worker.testSpecs.empty());
+}
diff --git a/tests/Progmasoft/RunnerPlanner.tests.cpp b/tests/Progmasoft/RunnerPlanner.tests.cpp
new file mode 100644
index 00000000..4c930632
--- /dev/null
+++ b/tests/Progmasoft/RunnerPlanner.tests.cpp
@@ -0,0 +1,599 @@
+// Copyright (c) 2026 Progmasoft.
+// SPDX-License-Identifier: MPL-2.0 WITH AdditionRef-Progmasoft-Exception-1.1
+
+// The planner decides which tests run, where, in which order and under
+// which limits, from the options, the history and the changed files. These
+// tests give it a catalog of their own, so no test of this binary is
+// involved.
+
+#include <Progmasoft/Runner/Catalog.hpp>
+#include <Progmasoft/Runner/Files.hpp>
+#include <Progmasoft/Runner/History.hpp>
+#include <Progmasoft/Runner/Planner.hpp>
+
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/matchers/catch_matchers_string.hpp>
+
+#include <algorithm>
+#include <chrono>
+#include <filesystem>
+#include <fstream>
+#include <map>
+#include <set>
+#include <string>
+#include <vector>
+
+namespace
+{
+    namespace Runner = Progmasoft::Catch3::Runner;
+    using Catch::Matchers::ContainsSubstring;
+    using Progmasoft::Catch3::Attempt;
+    using Progmasoft::Catch3::Outcome;
+    using Progmasoft::Catch3::RunResult;
+    using Progmasoft::Catch3::TestResult;
+    using std::chrono::milliseconds;
+
+    /// A directory of its own, removed at the end of the test.
+    class Scratch final
+    {
+    public:
+        Scratch()
+        {
+            std::error_code error;
+            path_ = std::filesystem::temp_directory_path(error) /
+                    ("catch3-planner-" + Runner::UniqueName());
+            std::filesystem::create_directories(path_, error);
+        }
+        Scratch(const Scratch &) = delete;
+        Scratch &
+        operator=(const Scratch &) = delete;
+        ~Scratch()
+        {
+            std::error_code error;
+            std::filesystem::remove_all(path_, error);
+        }
+
+        [[nodiscard]] const std::filesystem::path &
+        Path() const noexcept