Explain gtest experimental

[mark-undoio]

Early support for debugging Google Test binaries.

This makes use of the gtest_annotations addon, which uses the undoex library to create annotations within a recording. This allows Explain to list test results, jump to specific test failures and then resume debugging the case at hand.

If Google Test support is not present the relevant tools will return an error (ideally we'd only expose them when Google Test support is present but Claude doesn't handle tool changes currently).

[mark-undoio]

The program that I tested against was:

#include <gtest/gtest.h>
#include <undo_gtest_annotation.h>
#include <algorithm>
#include <numeric>
#include <vector>
#include <stdexcept>

TEST(StandardAlgorithms, SortVector) {
    std::vector<int> numbers = {5, 2, 8, 1, 9};
    std::sort(numbers.begin(), numbers.end());
    EXPECT_EQ(numbers[0], 1);
    EXPECT_EQ(numbers[4], 9);
}

TEST(StandardAlgorithms, AccumulateSum) {
    std::vector<int> numbers = {1, 2, 3, 4, 5};
    int sum = std::accumulate(numbers.begin(), numbers.end(), 0);
    EXPECT_EQ(sum, 15);
}

TEST(StandardAlgorithms, FindElement) {
    std::vector<int> numbers = {10, 20, 30, 40, 50};
    auto it = std::find(numbers.begin(), numbers.end(), 30);
    EXPECT_NE(it, numbers.end());
    EXPECT_EQ(*it, 30);
}

TEST(StandardAlgorithms, CountElements) {
    std::vector<int> numbers = {1, 2, 3, 4, 5};
    int count = std::count_if(numbers.begin(), numbers.end(),
                               [](int n) { return n > 0; });
    if (count > 0) {
        throw std::runtime_error("Unexpected value encountered");
    }
    EXPECT_EQ(count, 5);  // This line won't be reached
}

TEST(StandardAlgorithms, TransformVector) {
    std::vector<int> numbers = {1, 2, 3, 4, 5};
    std::vector<int> doubled(numbers.size());
    std::transform(numbers.begin(), numbers.end(), doubled.begin(),
                   [](int n) { return n * 2; });
    EXPECT_EQ(doubled[0], 2);
    EXPECT_EQ(doubled[4], 10);
}

TEST(StandardAlgorithms, CopyVector) {
    std::vector<int> source = {7, 8, 9};
    std::vector<int> dest(source.size());
    std::copy(source.begin(), source.end(), dest.begin());
    EXPECT_EQ(dest, source);
}

GTEST_API_ int
main(int argc, char **argv)
{
    testing::InitGoogleTest(&argc, argv);

    testing::UnitTest::GetInstance()->listeners().Append(new undo_annotation::UndoAnnotationListener);
    return RUN_ALL_TESTS();
}

This was generated by Claude Code and provides a single failing test to step back into. With the exception handling + this additional Gtests support it's able to navigate straight to the test failure of interest and analyse within it.

In principle we could also set time limits to the boundaries of that test case - I've not experimented with that. In the general case we might also want to be able to identify stale state from previous tests in the recording so it's not clear to me that doing so would always be a good thing.

[barisione]

This could be a generator expression to avoid going through all the object files.