magnum/src/Magnum/DebugTools/Test/CompareImageTest.cpp

/*
    This file is part of Magnum.

    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019
              Vladimír Vondruš <mosra@centrum.cz>

    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included
    in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
*/

#include <sstream>
#include <numeric>
#include <Corrade/Containers/Array.h>
#include <Corrade/Containers/Optional.h>
#include <Corrade/PluginManager/Manager.h>
#include <Corrade/TestSuite/Tester.h>
#include <Corrade/TestSuite/Compare/Container.h>
#include <Corrade/TestSuite/Compare/File.h>
#include <Corrade/Utility/DebugStl.h>
#include <Corrade/Utility/Directory.h>
#include <Corrade/Utility/FormatStl.h>
#include <Corrade/Utility/String.h>

#include "Magnum/ImageView.h"
#include "Magnum/PixelFormat.h"
#include "Magnum/DebugTools/CompareImage.h"
#include "Magnum/Math/Functions.h"
#include "Magnum/Math/Color.h"
#include "Magnum/Trade/AbstractImageConverter.h"
#include "Magnum/Trade/AbstractImporter.h"

#include "configure.h"

namespace Magnum { namespace DebugTools { namespace Test { namespace {

struct CompareImageTest: TestSuite::Tester {
    explicit CompareImageTest();

    void formatUnknown();
    void formatHalf();
    void formatImplementationSpecific();

    void calculateDelta();
    void calculateDeltaStorage();
    void calculateDeltaSpecials();
    void calculateDeltaSpecials3();

    void deltaImage();
    void deltaImageScaling();
    void deltaImageColors();
    void deltaImageSpecials();

    void pixelDelta();
    void pixelDeltaOverflow();
    void pixelDeltaSpecials();

    void compareDifferentSize();
    void compareDifferentFormat();
    void compareSameZeroThreshold();
    void compareAboveThresholds();
    void compareAboveMaxThreshold();
    void compareAboveMeanThreshold();
    void compareSpecials();
    void compareSpecialsMeanOnly();
    void compareSpecialsDisallowedThreshold();

    void setupExternalPluginManager();
    void teardownExternalPluginManager();

    void image();
    void imageError();
    void imageFile();
    void imageFileError();
    void imageFilePluginLoadFailed();
    void imageFileActualLoadFailed();
    void imageFileExpectedLoadFailed();
    void imageFileActualIsCompressed();
    void imageFileExpectedIsCompressed();
    void imageToFile();
    void imageToFileError();
    void imageToFilePluginLoadFailed();
    void imageToFileExpectedLoadFailed();
    void imageToFileExpectedIsCompressed();
    void fileToImage();
    void fileToImageError();
    void fileToImagePluginLoadFailed();
    void fileToImageActualLoadFailed();
    void fileToImageActualIsCompressed();

    private:
        Containers::Optional<PluginManager::Manager<Trade::AbstractImporter>> _importerManager;
        Containers::Optional<PluginManager::Manager<Trade::AbstractImageConverter>> _converterManager;
};

CompareImageTest::CompareImageTest() {
    addTests({&CompareImageTest::formatUnknown,
              &CompareImageTest::formatHalf,
              &CompareImageTest::formatImplementationSpecific,

              &CompareImageTest::calculateDelta,
              &CompareImageTest::calculateDeltaStorage,
              &CompareImageTest::calculateDeltaSpecials,
              &CompareImageTest::calculateDeltaSpecials3,

              &CompareImageTest::deltaImage,
              &CompareImageTest::deltaImageScaling,
              &CompareImageTest::deltaImageColors,
              &CompareImageTest::deltaImageSpecials,

              &CompareImageTest::pixelDelta,
              &CompareImageTest::pixelDeltaOverflow,
              &CompareImageTest::pixelDeltaSpecials,

              &CompareImageTest::compareDifferentSize,
              &CompareImageTest::compareDifferentFormat,
              &CompareImageTest::compareSameZeroThreshold,
              &CompareImageTest::compareAboveThresholds,
              &CompareImageTest::compareAboveMaxThreshold,
              &CompareImageTest::compareAboveMeanThreshold,
              &CompareImageTest::compareSpecials,
              &CompareImageTest::compareSpecialsMeanOnly,
              &CompareImageTest::compareSpecialsDisallowedThreshold,

              &CompareImageTest::image,
              &CompareImageTest::imageError});

    addTests({&CompareImageTest::imageFile,
              &CompareImageTest::imageFileError},
        &CompareImageTest::setupExternalPluginManager,
        &CompareImageTest::teardownExternalPluginManager);

    addTests({&CompareImageTest::imageFilePluginLoadFailed});

    addTests({&CompareImageTest::imageFileActualLoadFailed,
              &CompareImageTest::imageFileExpectedLoadFailed},
        &CompareImageTest::setupExternalPluginManager,
        &CompareImageTest::teardownExternalPluginManager);

    addTests({&CompareImageTest::imageFileActualIsCompressed,
              &CompareImageTest::imageFileExpectedIsCompressed});

    addTests({&CompareImageTest::imageToFile,
              &CompareImageTest::imageToFileError},
        &CompareImageTest::setupExternalPluginManager,
        &CompareImageTest::teardownExternalPluginManager);

    addTests({&CompareImageTest::imageToFilePluginLoadFailed});

    addTests({&CompareImageTest::imageToFileExpectedLoadFailed},
        &CompareImageTest::setupExternalPluginManager,
        &CompareImageTest::teardownExternalPluginManager);

    addTests({&CompareImageTest::imageToFileExpectedIsCompressed});

    addTests({&CompareImageTest::fileToImage,
              &CompareImageTest::fileToImageError},
        &CompareImageTest::setupExternalPluginManager,
        &CompareImageTest::teardownExternalPluginManager);

    addTests({&CompareImageTest::fileToImagePluginLoadFailed});

    addTests({&CompareImageTest::fileToImageActualLoadFailed},
        &CompareImageTest::setupExternalPluginManager,
        &CompareImageTest::teardownExternalPluginManager);

    addTests({&CompareImageTest::fileToImageActualIsCompressed});

    /* Plugin manager setup is not done here, but in the
       setupExternalPluginManager() function */
}

const Float ActualRedData[] = {
     0.3f, 1.0f, 0.9f,
     0.9f, 0.6f, 0.2f,
    -0.1f, 1.0f, 0.0f
};

const Float ExpectedRedData[] = {
    0.65f, 1.0f, 0.6f,
    0.91f, 0.6f, 0.1f,
    0.02f, 0.0f, 0.0f
};

const Float DeltaRed[]{
    0.35f, 0.0f, 0.3f,
    0.01f, 0.0f, 0.1f,
    0.12f, 1.0f, 0.0f
};

const ImageView2D ActualRed{PixelFormat::R32F, {3, 3}, ActualRedData};
const ImageView2D ExpectedRed{PixelFormat::R32F, {3, 3}, ExpectedRedData};

void CompareImageTest::formatUnknown() {
    std::ostringstream out;
    Error redirectError{&out};

    ImageView2D image{PixelStorage{}, PixelFormat(0xdead), 0, 0, {}};
    Implementation::calculateImageDelta(image, image);

    CORRADE_COMPARE(out.str(), "DebugTools::CompareImage: unknown format PixelFormat(0xdead)\n");
}

void CompareImageTest::formatHalf() {
    std::ostringstream out;
    Error redirectError{&out};

    ImageView2D image{PixelFormat::RG16F, {}};
    Implementation::calculateImageDelta(image, image);

    CORRADE_COMPARE(out.str(), "DebugTools::CompareImage: half-float formats are not supported yet\n");
}

void CompareImageTest::formatImplementationSpecific() {
    std::ostringstream out;
    Error redirectError{&out};

    ImageView2D image{PixelStorage{}, pixelFormatWrap(0xdead), 0, 0, {}};
    Implementation::calculateImageDelta(image, image);

    CORRADE_COMPARE(out.str(), "DebugTools::CompareImage: can't compare implementation-specific pixel formats\n");
}

void CompareImageTest::calculateDelta() {
    Containers::Array<Float> delta;
    Float max, mean;
    std::tie(delta, max, mean) = Implementation::calculateImageDelta(ActualRed, ExpectedRed);

    CORRADE_COMPARE_AS(delta, Containers::arrayView(DeltaRed), TestSuite::Compare::Container);
    CORRADE_COMPARE(max, 1.0f);
    CORRADE_COMPARE(mean, 0.208889f);
}

/* Different storage for each */
const UnsignedByte ActualRgbData[] = {
       0,    0,    0,    0,    0,    0,    0,    0,
    0x56, 0xf8, 0x3a, 0x56, 0x47, 0xec,    0,    0,
    0x23, 0x57, 0x10, 0xab, 0xcd, 0x85,    0,    0
};

const UnsignedByte ExpectedRgbData[] = {
    0, 0, 0, 0x55, 0xf8, 0x3a, 0x56, 0x10, 0xed, 0, 0, 0,
    0, 0, 0, 0x23, 0x27, 0x10, 0xab, 0xcd, 0xfa, 0, 0, 0
};

const ImageView2D ActualRgb{PixelStorage{}.setSkip({0, 1, 0}),
    PixelFormat::RGB8Unorm, {2, 2}, ActualRgbData};
const ImageView2D ExpectedRgb{
    PixelStorage{}.setSkip({1, 0, 0}).setRowLength(3),
    PixelFormat::RGB8Unorm, {2, 2}, ExpectedRgbData};

void CompareImageTest::calculateDeltaStorage() {
    Containers::Array<Float> delta;
    Float max, mean;
    std::tie(delta, max, mean) = Implementation::calculateImageDelta(ActualRgb, ExpectedRgb);

    CORRADE_COMPARE_AS(delta, (Containers::Array<Float>{Containers::InPlaceInit, {
        1.0f/3.0f, (55.0f + 1.0f)/3.0f,
        48.0f/3.0f, 117.0f/3.0f
    }}), TestSuite::Compare::Container);
    CORRADE_COMPARE(max, 117.0f/3.0f);
    CORRADE_COMPARE(mean, 18.5f);
}

/* Variants:
    -   expected number, got inf (and inverse)
    -   expected number, got nan (and inverse)
    -   got inf in both (and again, but different sign)
    -   got nan in both
    -   got a number in both (twice, to ensure it's calculated correctly) */
const Float ActualDataSpecials[]{
    Constants::inf(), 0.3f,
    Constants::nan(), 0.3f,
    -Constants::inf(), -Constants::inf(),
    Constants::nan(),
    0.3f, 3.0f
};
const Float ExpectedDataSpecials[]{
    1.0f, -Constants::inf(),
    0.3f, Constants::nan(),
    -Constants::inf(), Constants::inf(),
    Constants::nan(),
    0.65f, -0.1f
};
const Float DeltaSpecials[]{
    Constants::inf(), Constants::inf(),
    Constants::nan(), Constants::nan(),
    0.0f, Constants::inf(),
    0.0f,
    0.35f, 3.1f
};

const ImageView2D ActualSpecials{PixelFormat::R32F, {9, 1}, ActualDataSpecials};
const ImageView2D ExpectedSpecials{PixelFormat::R32F, {9, 1}, ExpectedDataSpecials};

void CompareImageTest::calculateDeltaSpecials() {
    Containers::Array<Float> delta;
    Float max, mean;
    std::tie(delta, max, mean) = Implementation::calculateImageDelta(ActualSpecials, ExpectedSpecials);
    CORRADE_COMPARE_AS(Containers::arrayView(delta),
        Containers::arrayView(DeltaSpecials),
        TestSuite::Compare::Container);
    /* Max should be calculated *without* the specials because otherwise every
       other potential difference will be zero compared to infinity. OTOH mean
       needs to get "poisoned" by those in order to have *something* to fail
       the test with. */
    CORRADE_COMPARE(max, 3.1f);
    CORRADE_COMPARE(mean, -Constants::nan());
}

void CompareImageTest::calculateDeltaSpecials3() {
    /* Same as calculateDeltaSpecials(), but reinterpreting the data as
       a three-component vector in order to test per-component handling of
       specials */
    const ImageView2D actualSpecials3{PixelFormat::RGB32F, {3, 1}, ActualDataSpecials};
    const ImageView2D expectedSpecials3{PixelFormat::RGB32F, {3, 1}, ExpectedDataSpecials};

    Containers::Array<Float> delta;
    Float max, mean;
    std::tie(delta, max, mean) = Implementation::calculateImageDelta(actualSpecials3, expectedSpecials3);
    CORRADE_COMPARE_AS(delta, (Containers::Array<Float>{Containers::InPlaceInit, {
        Constants::nan(), Constants::nan(), 1.15f
    }}), TestSuite::Compare::Container);
    /* Max and mean should be calculated *without* the specials because
       otherwise every other potential difference will be zero compared to
       infinity */
    CORRADE_COMPARE(max, 1.15f);
    CORRADE_COMPARE(mean, -Constants::nan());
}

void CompareImageTest::deltaImage() {
    std::ostringstream out;
    Debug d{&out, Debug::Flag::DisableColors};

    Containers::Array<Float> delta{32*32};

    for(std::int_fast32_t x = 0; x != 32; ++x)
        for(std::int_fast32_t y = 0; y != 32; ++y)
            delta[y*32 + x] = Vector2{Float(x), Float(y)}.length()/Vector2{32.0f}.length();

    Implementation::printDeltaImage(d, delta, {32, 32}, 1.0f, 0.0f, 0.0f);
    CORRADE_COMPARE(out.str(),
        "          |$$$$$$$$$$0000000888888DDDDNNNNM|\n"
        "          |ZZZZZZZ$$$$$$$$0000008888DDDDNNN|\n"
        "          |ZZZZZZZZZZZZZ$$$$$$00008888DDDDN|\n"
        "          |IIIIIIIIIIZZZZZZZ$$$$00008888DDD|\n"
        "          |7777777IIIIIIIZZZZZ$$$$00008888D|\n"
        "          |???777777777IIIIIZZZZ$$$$0000888|\n"
        "          |??????????77777IIIIZZZZ$$$$00088|\n"
        "          |+++++++??????7777IIIIZZZZ$$$0008|\n"
        "          |=====++++++????7777IIIIZZZ$$$000|\n"
        "          |=========++++????7777IIIZZZ$$$00|\n"
        "          |~~~~~~~====++++????777IIIZZZ$$$0|\n"
        "          |:::::~~~~====++++???777IIIZZZ$$$|\n"
        "          |,::::::~~~~===+++????77IIIZZZ$$$|\n"
        "          |,,,,,::::~~~===+++???777IIIZZZ$$|\n"
        "          |...,,,,:::~~~===+++??777IIIZZZ$$|\n"
        "          | ....,,:::~~~===+++???777IIZZZ$$|\n");
}

void CompareImageTest::deltaImageScaling() {
    std::ostringstream out;
    Debug d{&out, Debug::Flag::DisableColors};

    Containers::Array<Float> delta{65*40};
    for(std::int_fast32_t x = 0; x != 65; ++x)
        for(std::int_fast32_t y = 0; y != 40; ++y)
            delta[y*65 + x] = Vector2{Float(x), Float(y)}.length()/Vector2{65.0f, 40.0f}.length();

    Implementation::printDeltaImage(d, delta, {65, 40}, 1.0f, 0.0f, 0.0f);
    CORRADE_COMPARE(out.str(),
        "          |777777IIIIIIZZZZ$$$0000888DDDNNMM|\n"
        "          |????777777IIIIZZZZ$$$000888DDDNNN|\n"
        "          |?????????7777IIIIZZZ$$$00888DDDNN|\n"
        "          |++++++++????777IIIZZZ$$$00088DDDN|\n"
        "          |======++++????777IIIZZ$$$00088DDD|\n"
        "          |~~~~~====+++???777IIIZZ$$$00888DD|\n"
        "          |::::~~~~===+++??777IIZZZ$$00088DD|\n"
        "          |,,::::~~~===++???777IIZZ$$$00888D|\n"
        "          |.,,,,:::~~===++???77IIZZZ$$000888|\n"
        "          |...,,,::~~~==++???77IIIZZ$$000888|\n");
}

void CompareImageTest::deltaImageColors() {
    /* Print for visual color verification */
    {
        Debug() << "Visual verification -- some letters should be yellow, some red, some white:";
        Debug d{Debug::Flag::NoNewlineAtTheEnd};
        Implementation::printDeltaImage(d, DeltaRed, {3, 3}, 2.0f, 0.5f, 0.2f);
    }

    std::ostringstream out;
    Debug dc{&out, Debug::Flag::DisableColors};
    Implementation::printDeltaImage(dc, DeltaRed, {3, 3}, 2.0f, 0.5f, 0.2f);
    /* Yes, there is half of the rows (2 instead of 3) in order to roughly
       preserve image ratio */
    CORRADE_COMPARE(out.str(),
        "          |.7 |\n"
        "          |: ,|\n");
}

void CompareImageTest::deltaImageSpecials() {
    const Float inf = Constants::inf(), nan = Constants::nan();
    /* Duplicate the rows as the delta image visualizer merges each two to
       preserve ratio */
    const Float delta[]{0.7f,  inf, 2.5f,
                        0.7f,  nan, 2.5f,
                         nan,  inf, 0.0f,
                         nan,  inf, 0.0f};

    std::ostringstream out;
    Debug dc{&out, Debug::Flag::DisableColors};
    Implementation::printDeltaImage(dc, delta, {3, 4}, 3.0f, 0.0f, 0.0f);
    /* Should show the max value for NaN and infs and the usual things
       otherwise */
    CORRADE_COMPARE(out.str(),
        "          |MM |\n"
        "          |~M8|\n");
}

void CompareImageTest::pixelDelta() {
    {
        Debug() << "Visual verification -- some lines should be yellow, some red:";
        Debug d;
        Implementation::printPixelDeltas(d, DeltaRed, ActualRed, ExpectedRed, 0.5f, 0.1f, 10);
    }

    std::ostringstream out;
    Debug d{&out, Debug::Flag::DisableColors};
    Implementation::printPixelDeltas(d, DeltaRed, ActualRed, ExpectedRed, 0.5f, 0.1f, 10);

    CORRADE_COMPARE(out.str(),
        "        Pixels above max/mean threshold:\n"
        "          [1,2] Vector(1), expected Vector(0) (Δ = 1)\n"
        "          [0,0] Vector(0.3), expected Vector(0.65) (Δ = 0.35)\n"
        "          [2,0] Vector(0.9), expected Vector(0.6) (Δ = 0.3)\n"
        "          [0,2] Vector(-0.1), expected Vector(0.02) (Δ = 0.12)");
}

void CompareImageTest::pixelDeltaOverflow() {
    std::ostringstream out;
    Debug d{&out, Debug::Flag::DisableColors};
    Implementation::printPixelDeltas(d, DeltaRed, ActualRed, ExpectedRed, 0.5f, 0.1f, 3);

    CORRADE_COMPARE(out.str(),
        "        Top 3 out of 4 pixels above max/mean threshold:\n"
        "          [1,2] Vector(1), expected Vector(0) (Δ = 1)\n"
        "          [0,0] Vector(0.3), expected Vector(0.65) (Δ = 0.35)\n"
        "          [2,0] Vector(0.9), expected Vector(0.6) (Δ = 0.3)");
}

void CompareImageTest::pixelDeltaSpecials() {
    std::ostringstream out;
    Debug d{&out, Debug::Flag::DisableColors};
    Implementation::printPixelDeltas(d, DeltaSpecials, ActualSpecials, ExpectedSpecials, 1.5f, 0.5f, 10);

    /* MSVC prints -nan(ind) instead of ±nan. But only sometimes. */
    #ifdef _MSC_VER
    CORRADE_COMPARE(out.str(),
        "        Pixels above max/mean threshold:\n"
        "          [5,0] Vector(-inf), expected Vector(inf) (Δ = inf)\n"
        "          [3,0] Vector(0.3), expected Vector(-nan(ind)) (Δ = -nan(ind))\n"
        "          [2,0] Vector(-nan(ind)), expected Vector(0.3) (Δ = -nan(ind))\n"
        "          [1,0] Vector(0.3), expected Vector(-inf) (Δ = inf)\n"
        "          [0,0] Vector(inf), expected Vector(1) (Δ = inf)\n"
        "          [8,0] Vector(3), expected Vector(-0.1) (Δ = 3.1)");
    #else
    CORRADE_COMPARE(out.str(),
        "        Pixels above max/mean threshold:\n"
        "          [5,0] Vector(-inf), expected Vector(inf) (Δ = inf)\n"
        "          [3,0] Vector(0.3), expected Vector(nan) (Δ = nan)\n"
        "          [2,0] Vector(nan), expected Vector(0.3) (Δ = nan)\n"
        "          [1,0] Vector(0.3), expected Vector(-inf) (Δ = inf)\n"
        "          [0,0] Vector(inf), expected Vector(1) (Δ = inf)\n"
        "          [8,0] Vector(3), expected Vector(-0.1) (Δ = 3.1)");
    #endif
}

void CompareImageTest::compareDifferentSize() {
    std::stringstream out;

    ImageView2D a{PixelFormat::RG8UI, {3, 4}, nullptr};
    ImageView2D b{PixelFormat::RG8UI, {3, 5}, nullptr};

    {
        TestSuite::Comparator<CompareImage> compare{{}, {}};
        TestSuite::ComparisonStatusFlags flags = compare(a, b);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Error e(&out);
        compare.printMessage(flags, e, "a", "b");
    }

    CORRADE_COMPARE(out.str(), "Images a and b have different size, actual Vector(3, 4) but Vector(3, 5) expected.\n");
}

void CompareImageTest::compareDifferentFormat() {
    std::stringstream out;

    ImageView2D a{PixelFormat::RGBA32F, {3, 4}, nullptr};
    ImageView2D b{PixelFormat::RGB32F, {3, 4}, nullptr};

    {
        TestSuite::Comparator<CompareImage> compare{{}, {}};
        TestSuite::ComparisonStatusFlags flags = compare(a, b);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Error e(&out);
        compare.printMessage(flags, e, "a", "b");
    }

    CORRADE_COMPARE(out.str(), "Images a and b have different format, actual PixelFormat::RGBA32F but PixelFormat::RGB32F expected.\n");
}

void CompareImageTest::compareSameZeroThreshold() {
    using namespace Math::Literals;

    const Color3 data[] = {
        0xcafeba_rgbf, 0xdeadbe_rgbf,
        0xbadc0d_rgbf, 0xbeefe0_rgbf
    };

    const ImageView2D image{PixelFormat::RGB32F, {2, 2}, data};
    CORRADE_COMPARE((TestSuite::Comparator<CompareImage>{0.0f, 0.0f}(image, image)), TestSuite::ComparisonStatusFlags{});
}

void CompareImageTest::compareAboveThresholds() {
    std::stringstream out;

    {
        TestSuite::Comparator<CompareImage> compare{20.0f, 10.0f};
        TestSuite::ComparisonStatusFlags flags = compare(ActualRgb, ExpectedRgb);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(),
        "Images a and b have both max and mean delta above threshold, actual 39/18.5 but at most 20/10 expected. Delta image:\n"
        "          |?M|\n"
        "        Pixels above max/mean threshold:\n"
        "          [1,1] #abcd85, expected #abcdfa (Δ = 39)\n"
        "          [1,0] #5647ec, expected #5610ed (Δ = 18.6667)\n"
        "          [0,1] #235710, expected #232710 (Δ = 16)\n");
}

void CompareImageTest::compareAboveMaxThreshold() {
    std::stringstream out;

    {
        TestSuite::Comparator<CompareImage> compare{30.0f, 20.0f};
        TestSuite::ComparisonStatusFlags flags = compare(ActualRgb, ExpectedRgb);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(),
        "Images a and b have max delta above threshold, actual 39 but at most 30 expected. Mean delta 18.5 is below threshold 20. Delta image:\n"
        "          |?M|\n"
        "        Pixels above max/mean threshold:\n"
        "          [1,1] #abcd85, expected #abcdfa (Δ = 39)\n");
}

void CompareImageTest::compareAboveMeanThreshold() {
    std::stringstream out;

    {
        TestSuite::Comparator<CompareImage> compare{50.0f, 18.0f};
        TestSuite::ComparisonStatusFlags flags = compare(ActualRgb, ExpectedRgb);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(),
        "Images a and b have mean delta above threshold, actual 18.5 but at most 18 expected. Max delta 39 is below threshold 50. Delta image:\n"
        "          |?M|\n"
        "        Pixels above max/mean threshold:\n"
        "          [1,1] #abcd85, expected #abcdfa (Δ = 39)\n"
        "          [1,0] #5647ec, expected #5610ed (Δ = 18.6667)\n");
}

void CompareImageTest::compareSpecials() {
    std::stringstream out;

    {
        TestSuite::Comparator<CompareImage> compare{1.5f, 0.5f};
        TestSuite::ComparisonStatusFlags flags = compare(ActualSpecials, ExpectedSpecials);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    /* Apple platforms, Android, Emscripten and MinGW32 don't print signed
       NaNs. This is *not* a libc++ thing, tho -- libc++ on Linux prints signed NaNs. */
    #if defined(CORRADE_TARGET_APPLE) || defined(CORRADE_TARGET_ANDROID) || defined(CORRADE_TARGET_EMSCRIPTEN) || defined(__MINGW32__)
    CORRADE_COMPARE(out.str(),
        "Images a and b have both max and mean delta above threshold, actual 3.1/nan but at most 1.5/0.5 expected. Delta image:\n"
        "          |MMMM M ,M|\n"
        "        Pixels above max/mean threshold:\n"
        "          [5,0] Vector(-inf), expected Vector(inf) (Δ = inf)\n"
        "          [3,0] Vector(0.3), expected Vector(nan) (Δ = nan)\n"
        "          [2,0] Vector(nan), expected Vector(0.3) (Δ = nan)\n"
        "          [1,0] Vector(0.3), expected Vector(-inf) (Δ = inf)\n"
        "          [0,0] Vector(inf), expected Vector(1) (Δ = inf)\n"
        "          [8,0] Vector(3), expected Vector(-0.1) (Δ = 3.1)\n");

    /* MSVC prints -nan(ind) instead of ±nan. But only sometimes. */
    #elif defined(_MSC_VER)
    CORRADE_COMPARE(out.str(),
        "Images a and b have both max and mean delta above threshold, actual 3.1/-nan(ind) but at most 1.5/0.5 expected. Delta image:\n"
        "          |MMMM M ,M|\n"
        "        Pixels above max/mean threshold:\n"
        "          [5,0] Vector(-inf), expected Vector(inf) (Δ = inf)\n"
        "          [3,0] Vector(0.3), expected Vector(-nan(ind)) (Δ = nan)\n"
        "          [2,0] Vector(-nan(ind)), expected Vector(0.3) (Δ = nan)\n"
        "          [1,0] Vector(0.3), expected Vector(-inf) (Δ = inf)\n"
        "          [0,0] Vector(inf), expected Vector(1) (Δ = inf)\n"
        "          [8,0] Vector(3), expected Vector(-0.1) (Δ = 3.1)\n");

    /* Linux */
    #else
    CORRADE_COMPARE(out.str(),
        "Images a and b have both max and mean delta above threshold, actual 3.1/-nan but at most 1.5/0.5 expected. Delta image:\n"
        "          |MMMM M ,M|\n"
        "        Pixels above max/mean threshold:\n"
        "          [5,0] Vector(-inf), expected Vector(inf) (Δ = inf)\n"
        "          [3,0] Vector(0.3), expected Vector(nan) (Δ = nan)\n"
        "          [2,0] Vector(nan), expected Vector(0.3) (Δ = nan)\n"
        "          [1,0] Vector(0.3), expected Vector(-inf) (Δ = inf)\n"
        "          [0,0] Vector(inf), expected Vector(1) (Δ = inf)\n"
        "          [8,0] Vector(3), expected Vector(-0.1) (Δ = 3.1)\n");
    #endif
}

void CompareImageTest::compareSpecialsMeanOnly() {
    std::stringstream out;

    {
        TestSuite::Comparator<CompareImage> compare{15.0f, 0.5f};
        TestSuite::ComparisonStatusFlags flags = compare(ActualSpecials, ExpectedSpecials);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    /* Apple platforms, Android, Emscripten and MinGW32 don't print signed
       NaNs. This is *not* a libc++ thing, tho -- libc++ on Linux prints signed NaNs. */
    #if defined(CORRADE_TARGET_APPLE) || defined(CORRADE_TARGET_ANDROID) || defined(CORRADE_TARGET_EMSCRIPTEN) || defined(__MINGW32__)
    CORRADE_COMPARE(out.str(),
        "Images a and b have mean delta above threshold, actual nan but at most 0.5 expected. Max delta 3.1 is below threshold 15. Delta image:\n"
        "          |MMMM M ,M|\n"
        "        Pixels above max/mean threshold:\n"
        "          [5,0] Vector(-inf), expected Vector(inf) (Δ = inf)\n"
        "          [3,0] Vector(0.3), expected Vector(nan) (Δ = nan)\n"
        "          [2,0] Vector(nan), expected Vector(0.3) (Δ = nan)\n"
        "          [1,0] Vector(0.3), expected Vector(-inf) (Δ = inf)\n"
        "          [0,0] Vector(inf), expected Vector(1) (Δ = inf)\n"
        "          [8,0] Vector(3), expected Vector(-0.1) (Δ = 3.1)\n");

    /* MSVC prints -nan(ind) instead of ±nan. But only sometimes. */
    #elif defined(CORRADE_TARGET_WINDOWS) && defined(_MSC_VER)
    CORRADE_COMPARE(out.str(),
        "Images a and b have mean delta above threshold, actual -nan(ind) but at most 0.5 expected. Max delta 3.1 is below threshold 15. Delta image:\n"
        "          |MMMM M ,M|\n"
        "        Pixels above max/mean threshold:\n"
        "          [5,0] Vector(-inf), expected Vector(inf) (Δ = inf)\n"
        "          [3,0] Vector(0.3), expected Vector(-nan(ind)) (Δ = nan)\n"
        "          [2,0] Vector(-nan(ind)), expected Vector(0.3) (Δ = nan)\n"
        "          [1,0] Vector(0.3), expected Vector(-inf) (Δ = inf)\n"
        "          [0,0] Vector(inf), expected Vector(1) (Δ = inf)\n"
        "          [8,0] Vector(3), expected Vector(-0.1) (Δ = 3.1)\n");

    /* Linux */
    #else
    CORRADE_COMPARE(out.str(),
        "Images a and b have mean delta above threshold, actual -nan but at most 0.5 expected. Max delta 3.1 is below threshold 15. Delta image:\n"
        "          |MMMM M ,M|\n"
        "        Pixels above max/mean threshold:\n"
        "          [5,0] Vector(-inf), expected Vector(inf) (Δ = inf)\n"
        "          [3,0] Vector(0.3), expected Vector(nan) (Δ = nan)\n"
        "          [2,0] Vector(nan), expected Vector(0.3) (Δ = nan)\n"
        "          [1,0] Vector(0.3), expected Vector(-inf) (Δ = inf)\n"
        "          [0,0] Vector(inf), expected Vector(1) (Δ = inf)\n"
        "          [8,0] Vector(3), expected Vector(-0.1) (Δ = 3.1)\n");
    #endif
}

void CompareImageTest::compareSpecialsDisallowedThreshold() {
    std::stringstream out;

    {
        Error redirectError{&out};
        TestSuite::Comparator<CompareImage> a{Constants::inf(), 0.3f};
        TestSuite::Comparator<CompareImage> b{0.3f, Constants::nan()};
    }

    CORRADE_COMPARE(out.str(),
        "DebugTools::CompareImage: thresholds can't be NaN or infinity\n"
        "DebugTools::CompareImage: thresholds can't be NaN or infinity\n");
}

void CompareImageTest::setupExternalPluginManager() {
    _importerManager.emplace("nonexistent");
    _converterManager.emplace("nonexistent");
    /* Load the plugin directly from the build tree. Otherwise it's either
       static and already loaded or not present in the build tree */
    #ifdef ANYIMAGEIMPORTER_PLUGIN_FILENAME
    CORRADE_INTERNAL_ASSERT(_importerManager->load(ANYIMAGEIMPORTER_PLUGIN_FILENAME) & PluginManager::LoadState::Loaded);
    #endif
    #ifdef ANYIMAGECONVERTER_PLUGIN_FILENAME
    CORRADE_INTERNAL_ASSERT(_converterManager->load(ANYIMAGECONVERTER_PLUGIN_FILENAME) & PluginManager::LoadState::Loaded);
    #endif
    #ifdef TGAIMPORTER_PLUGIN_FILENAME
    CORRADE_INTERNAL_ASSERT(_importerManager->load(TGAIMPORTER_PLUGIN_FILENAME) & PluginManager::LoadState::Loaded);
    #endif
    #ifdef TGAIMAGECONVERTER_PLUGIN_FILENAME
    CORRADE_INTERNAL_ASSERT(_converterManager->load(TGAIMAGECONVERTER_PLUGIN_FILENAME) & PluginManager::LoadState::Loaded);
    #endif
}

void CompareImageTest::teardownExternalPluginManager() {
    _importerManager = Containers::NullOpt;
    _converterManager = Containers::NullOpt;
}

constexpr const char* ImageCompareError =
    "Images a and b have both max and mean delta above threshold, actual 39/18.5 but at most 20/10 expected. Delta image:\n"
    "          |?M|\n"
    "        Pixels above max/mean threshold:\n"
    "          [1,1] #abcd85, expected #abcdfa (Δ = 39)\n"
    "          [1,0] #5647ec, expected #5610ed (Δ = 18.6667)\n"
    "          [0,1] #235710, expected #232710 (Δ = 16)\n";

void CompareImageTest::image() {
    CORRADE_COMPARE_WITH(ActualRgb, ExpectedRgb, (CompareImage{40.0f, 20.0f}));

    /* No diagnostic as there's no error */
    TestSuite::Comparator<CompareImage> compare{40.0f, 20.0f};
    CORRADE_COMPARE(compare(ActualRgb, ExpectedRgb), TestSuite::ComparisonStatusFlags{});
}

void CompareImageTest::imageError() {
    std::stringstream out;

    {
        TestSuite::Comparator<CompareImage> compare{20.0f, 10.0f};
        TestSuite::ComparisonStatusFlags flags = compare(ActualRgb, ExpectedRgb);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(), ImageCompareError);
}

void CompareImageTest::imageFile() {
    if(_importerManager->loadState("AnyImageImporter") == PluginManager::LoadState::NotFound ||
       _importerManager->loadState("TgaImporter") == PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter or TgaImporter plugins not found.");

    CORRADE_COMPARE_WITH(
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"),
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageExpected.tga"),
        (CompareImageFile{*_importerManager, 40.0f, 20.0f}));

    /* No diagnostic as there's no error */
    TestSuite::Comparator<CompareImageFile> compare{&*_importerManager, nullptr, 40.0f, 20.0f};
    CORRADE_COMPARE(compare(
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"),
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageExpected.tga")),
        TestSuite::ComparisonStatusFlags{});
}

void CompareImageTest::imageFileError() {
    if(_importerManager->loadState("AnyImageImporter") == PluginManager::LoadState::NotFound ||
       _importerManager->loadState("TgaImporter") == PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter or TgaImporter plugins not found.");

    std::stringstream out;

    TestSuite::Comparator<CompareImageFile> compare{&*_importerManager, &*_converterManager, 20.0f, 10.0f};
    TestSuite::ComparisonStatusFlags flags = compare(
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"),
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageExpected.tga"));
    /* The diagnostic flag should be slapped on the failure coming from the
       operator() comparing two ImageViews */
    CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed|TestSuite::ComparisonStatusFlag::Diagnostic);

    {
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(), ImageCompareError);

    /* Create the output dir if it doesn't exist, but avoid stale files making
       false positives */
    CORRADE_VERIFY(Utility::Directory::mkpath(COMPAREIMAGETEST_SAVE_DIR));
    std::string filename = Utility::Directory::join(COMPAREIMAGETEST_SAVE_DIR, "CompareImageExpected.tga");
    if(Utility::Directory::exists(filename))
        CORRADE_VERIFY(Utility::Directory::rm(filename));

    {
        out.str({});
        Debug redirectOutput(&out);
        compare.saveDiagnostic(flags, redirectOutput, COMPAREIMAGETEST_SAVE_DIR);
    }

    /* We expect the *actual* contents, but under the *expected* filename.
       Comparing file contents, expecting the converter makes exactly the same
       file. */
    CORRADE_COMPARE(out.str(), Utility::formatString("-> {}\n", filename));
    CORRADE_COMPARE_AS(filename,
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"), TestSuite::Compare::File);
}

void CompareImageTest::imageFilePluginLoadFailed() {
    PluginManager::Manager<Trade::AbstractImporter> manager{"nonexistent"};
    if(manager.loadState("AnyImageImporter") != PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter plugin found, can't test.");

    std::stringstream out;

    {
        TestSuite::Comparator<CompareImageFile> compare{&manager, nullptr, 20.0f, 10.0f};
        TestSuite::ComparisonStatusFlags flags = compare(
            Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"),
            Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageExpected.tga"));
        /* Can't load a plugin, so we can't open the file, so we can't save
           it either and thus no diagnostic */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(), "AnyImageImporter plugin could not be loaded.\n");
}

void CompareImageTest::imageFileActualLoadFailed() {
    if(_importerManager->loadState("AnyImageImporter") == PluginManager::LoadState::NotFound ||
       _importerManager->loadState("TgaImporter") == PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter or TgaImporter plugins not found.");

    std::stringstream out;

    {
        TestSuite::Comparator<CompareImageFile> compare{&*_importerManager, nullptr, 20.0f, 10.0f};
        TestSuite::ComparisonStatusFlags flags = compare("nonexistent.tga",
            Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageExpected.tga"));
        /* We can't open the file, so we can't save it either and thus no
           diagnostic */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(), "Actual image a (nonexistent.tga) could not be loaded.\n");
}

void CompareImageTest::imageFileExpectedLoadFailed() {
    if(_importerManager->loadState("AnyImageImporter") == PluginManager::LoadState::NotFound ||
       _importerManager->loadState("TgaImporter") == PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter or TgaImporter plugins not found.");

    std::stringstream out;

    TestSuite::Comparator<CompareImageFile> compare{&*_importerManager, &*_converterManager, 20.0f, 10.0f};
    TestSuite::ComparisonStatusFlags flags = compare(
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"),
        "nonexistent.tga");
    /* Actual file *could* be loaded, so save it! */
    CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed|TestSuite::ComparisonStatusFlag::Diagnostic);

    {
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(), "Expected image b (nonexistent.tga) could not be loaded.\n");

    /* Create the output dir if it doesn't exist, but avoid stale files making
       false positives */
    CORRADE_VERIFY(Utility::Directory::mkpath(COMPAREIMAGETEST_SAVE_DIR));
    std::string filename = Utility::Directory::join(COMPAREIMAGETEST_SAVE_DIR, "nonexistent.tga");
    if(Utility::Directory::exists(filename))
        CORRADE_VERIFY(Utility::Directory::rm(filename));

    {
        out.str({});
        Debug redirectOutput(&out);
        compare.saveDiagnostic(flags, redirectOutput, COMPAREIMAGETEST_SAVE_DIR);
    }

    /* We expect the *actual* contents, but under the *expected* filename.
       Comparing file contents, expecting the converter makes exactly the same
       file. */
    CORRADE_COMPARE(out.str(), Utility::formatString("-> {}\n", filename));
    CORRADE_COMPARE_AS(filename,
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"), TestSuite::Compare::File);
}

void CompareImageTest::imageFileActualIsCompressed() {
    PluginManager::Manager<Trade::AbstractImporter> manager;
    if(manager.load("AnyImageImporter") < PluginManager::LoadState::Loaded ||
       manager.load("DdsImporter") < PluginManager::LoadState::Loaded)
        CORRADE_SKIP("AnyImageImporter or DdsImporter plugins can't be loaded.");

    std::stringstream out;

    {
        TestSuite::Comparator<CompareImageFile> compare{&manager, nullptr, 20.0f, 10.0f};
        TestSuite::ComparisonStatusFlags flags = compare(
            Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageCompressed.dds"),
            Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageExpected.tga"));
        /* We most probably couldn't save the file because it's in a different
           format, so no diagnostic */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(Utility::String::replaceFirst(out.str(), DEBUGTOOLS_TEST_DIR, "..."), "Actual image a (.../CompareImageCompressed.dds) is compressed, comparison not possible.\n");
}

void CompareImageTest::imageFileExpectedIsCompressed() {
    PluginManager::Manager<Trade::AbstractImporter> manager;
    if(manager.load("AnyImageImporter") < PluginManager::LoadState::Loaded ||
       manager.load("DdsImporter") < PluginManager::LoadState::Loaded)
        CORRADE_SKIP("AnyImageImporter or DdsImporter plugins can't be loaded.");

    std::stringstream out;

    TestSuite::Comparator<CompareImageFile> compare{&manager, nullptr, 20.0f, 10.0f};
    TestSuite::ComparisonStatusFlags flags = compare(
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"),
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageCompressed.dds"));
    /* Actual file is not, so save it! */
    CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed|TestSuite::ComparisonStatusFlag::Diagnostic);

    {
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    /* Create the output dir if it doesn't exist, but avoid stale files making
       false positives */
    CORRADE_VERIFY(Utility::Directory::mkpath(COMPAREIMAGETEST_SAVE_DIR));
    std::string filename = Utility::Directory::join(COMPAREIMAGETEST_SAVE_DIR, "CompareImageCompressed.dds");
    if(Utility::Directory::exists(filename))
        CORRADE_VERIFY(Utility::Directory::rm(filename));

    /* This will attempt to save a DDS and then fails, because we have no DDS
       exporter. */
    Debug d;
    compare.saveDiagnostic(flags, d, COMPAREIMAGETEST_SAVE_DIR);
    CORRADE_VERIFY(!Utility::Directory::exists(filename));
}

void CompareImageTest::imageToFile() {
    if(_importerManager->loadState("AnyImageImporter") == PluginManager::LoadState::NotFound ||
       _importerManager->loadState("TgaImporter") == PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter or TgaImporter plugins not found.");

    CORRADE_COMPARE_WITH(ActualRgb,
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageExpected.tga"),
        (CompareImageToFile{*_importerManager, 40.0f, 20.0f}));

    /* No diagnostic as there's no error */
    TestSuite::Comparator<CompareImageToFile> compare{&*_importerManager, nullptr, 40.0f, 20.0f};
    CORRADE_COMPARE(compare(ActualRgb, Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageExpected.tga")),
        TestSuite::ComparisonStatusFlags{});
}

void CompareImageTest::imageToFileError() {
    if(_importerManager->loadState("AnyImageImporter") == PluginManager::LoadState::NotFound ||
       _importerManager->loadState("TgaImporter") == PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter or TgaImporter plugins not found.");

    std::stringstream out;

    TestSuite::Comparator<CompareImageToFile> compare{&*_importerManager, &*_converterManager, 20.0f, 10.0f};
    TestSuite::ComparisonStatusFlags flags = compare(ActualRgb,
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageExpected.tga"));
    /* The diagnostic flag should be slapped on the failure coming from the
       operator() comparing two ImageViews */
    CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed|TestSuite::ComparisonStatusFlag::Diagnostic);

    {
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(), ImageCompareError);

    /* Create the output dir if it doesn't exist, but avoid stale files making
       false positives */
    CORRADE_VERIFY(Utility::Directory::mkpath(COMPAREIMAGETEST_SAVE_DIR));
    std::string filename = Utility::Directory::join(COMPAREIMAGETEST_SAVE_DIR, "CompareImageExpected.tga");
    if(Utility::Directory::exists(filename))
        CORRADE_VERIFY(Utility::Directory::rm(filename));

    {
        out.str({});
        Debug redirectOutput(&out);
        compare.saveDiagnostic(flags, redirectOutput, COMPAREIMAGETEST_SAVE_DIR);
    }

    /* We expect the *actual* contents, but under the *expected* filename.
       Comparing file contents, expecting the converter makes exactly the same
       file. */
    CORRADE_COMPARE(out.str(), Utility::formatString("-> {}\n", filename));
    CORRADE_COMPARE_AS(filename,
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"), TestSuite::Compare::File);
}

void CompareImageTest::imageToFilePluginLoadFailed() {
    PluginManager::Manager<Trade::AbstractImporter> manager{"nonexistent"};
    if(manager.loadState("AnyImageImporter") != PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter plugin found, can't test.");

    std::stringstream out;

    {
        TestSuite::Comparator<CompareImageToFile> compare{&manager, nullptr, 20.0f, 10.0f};
        TestSuite::ComparisonStatusFlags flags = compare(ActualRgb,
            Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageExpected.tga"));
        /* Can't load a plugin, so we can't open the file, so we can't save
           it either and thus no diagnostic */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(), "AnyImageImporter plugin could not be loaded.\n");
}

void CompareImageTest::imageToFileExpectedLoadFailed() {
    if(_importerManager->loadState("AnyImageImporter") == PluginManager::LoadState::NotFound ||
       _importerManager->loadState("TgaImporter") == PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter or TgaImporter plugins not found.");

    std::stringstream out;

    TestSuite::Comparator<CompareImageToFile> compare{&*_importerManager, &*_converterManager, 20.0f, 10.0f};
    TestSuite::ComparisonStatusFlags flags = compare(ActualRgb, "nonexistent.tga");
    /* Actual file *could* be loaded, so save it! */
    CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed|TestSuite::ComparisonStatusFlag::Diagnostic);

    {
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(), "Expected image b (nonexistent.tga) could not be loaded.\n");

    /* Create the output dir if it doesn't exist, but avoid stale files making
       false positives */
    CORRADE_VERIFY(Utility::Directory::mkpath(COMPAREIMAGETEST_SAVE_DIR));
    std::string filename = Utility::Directory::join(COMPAREIMAGETEST_SAVE_DIR, "nonexistent.tga");
    if(Utility::Directory::exists(filename))
        CORRADE_VERIFY(Utility::Directory::rm(filename));

    {
        out.str({});
        Debug redirectOutput(&out);
        compare.saveDiagnostic(flags, redirectOutput, COMPAREIMAGETEST_SAVE_DIR);
    }

    /* We expect the *actual* contents, but under the *expected* filename.
       Comparing file contents, expecting the converter makes exactly the same
       file. */
    CORRADE_COMPARE(out.str(), Utility::formatString("-> {}\n", filename));
    CORRADE_COMPARE_AS(filename,
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"), TestSuite::Compare::File);
}

void CompareImageTest::imageToFileExpectedIsCompressed() {
    PluginManager::Manager<Trade::AbstractImporter> manager;
    if(manager.load("AnyImageImporter") < PluginManager::LoadState::Loaded ||
       manager.load("DdsImporter") < PluginManager::LoadState::Loaded)
            CORRADE_SKIP("AnyImageImporter or DdsImporter plugins can't be loaded.");

    std::stringstream out;

    TestSuite::Comparator<CompareImageToFile> compare{&manager, nullptr, 20.0f, 10.0f};
    TestSuite::ComparisonStatusFlags flags = compare(ActualRgb,
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageCompressed.dds"));
    /* Actual file is not, so save it! */
    CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed|TestSuite::ComparisonStatusFlag::Diagnostic);

    {
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(Utility::String::replaceFirst(out.str(), DEBUGTOOLS_TEST_DIR, "..."),
        "Expected image b (.../CompareImageCompressed.dds) is compressed, comparison not possible.\n");

    /* Create the output dir if it doesn't exist, but avoid stale files making
       false positives */
    CORRADE_VERIFY(Utility::Directory::mkpath(COMPAREIMAGETEST_SAVE_DIR));
    std::string filename = Utility::Directory::join(COMPAREIMAGETEST_SAVE_DIR, "CompareImageCompressed.dds");
    if(Utility::Directory::exists(filename))
        CORRADE_VERIFY(Utility::Directory::rm(filename));

    /* This will attempt to save a DDS and then fails, because we have no DDS
       exporter. */
    Debug d;
    compare.saveDiagnostic(flags, d, COMPAREIMAGETEST_SAVE_DIR);
    CORRADE_VERIFY(!Utility::Directory::exists(filename));
}

void CompareImageTest::fileToImage() {
    if(_importerManager->loadState("AnyImageImporter") == PluginManager::LoadState::NotFound ||
       _importerManager->loadState("TgaImporter") == PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter or TgaImporter plugins not found.");

    CORRADE_COMPARE_WITH(
        Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"),
        ExpectedRgb,
        (CompareFileToImage{*_importerManager, 40.0f, 20.0f}));

    /* No diagnostic as there's no error */
    TestSuite::Comparator<CompareFileToImage> compare{&*_importerManager, 40.0f, 20.0f};
    CORRADE_COMPARE(compare(Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"),
        ExpectedRgb), TestSuite::ComparisonStatusFlags{});
}

void CompareImageTest::fileToImageError() {
    if(_importerManager->loadState("AnyImageImporter") == PluginManager::LoadState::NotFound ||
       _importerManager->loadState("TgaImporter") == PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter or TgaImporter plugins not found.");

    std::stringstream out;

    {
        TestSuite::Comparator<CompareFileToImage> compare{&*_importerManager, 20.0f, 10.0f};
        TestSuite::ComparisonStatusFlags flags = compare(
            Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"),
            ExpectedRgb);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(), ImageCompareError);
}

void CompareImageTest::fileToImagePluginLoadFailed() {
    PluginManager::Manager<Trade::AbstractImporter> manager{"nonexistent"};
    if(manager.loadState("AnyImageImporter") != PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter plugin found, can't test.");

    std::stringstream out;

    {
        TestSuite::Comparator<CompareFileToImage> compare{&manager, 20.0f, 10.0f};
        TestSuite::ComparisonStatusFlags flags = compare(
            Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageActual.tga"),
            ExpectedRgb);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(), "AnyImageImporter plugin could not be loaded.\n");
}

void CompareImageTest::fileToImageActualLoadFailed() {
    if(_importerManager->loadState("AnyImageImporter") == PluginManager::LoadState::NotFound ||
       _importerManager->loadState("TgaImporter") == PluginManager::LoadState::NotFound)
        CORRADE_SKIP("AnyImageImporter or TgaImporter plugins not found.");

    std::stringstream out;

    {
        TestSuite::Comparator<CompareFileToImage> compare{&*_importerManager, 20.0f, 10.0f};
        TestSuite::ComparisonStatusFlags flags = compare("nonexistent.tga", ExpectedRgb);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(out.str(), "Actual image a (nonexistent.tga) could not be loaded.\n");
}

void CompareImageTest::fileToImageActualIsCompressed() {
    PluginManager::Manager<Trade::AbstractImporter> manager;
    if(manager.load("AnyImageImporter") < PluginManager::LoadState::Loaded ||
       manager.load("DdsImporter") < PluginManager::LoadState::Loaded)
            CORRADE_SKIP("AnyImageImporter or DdsImporter plugins can't be loaded.");

    std::stringstream out;

    {
        TestSuite::Comparator<CompareFileToImage> compare{&manager, 20.0f, 10.0f};
        TestSuite::ComparisonStatusFlags flags = compare(Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "CompareImageCompressed.dds"), ExpectedRgb);
        /* No diagnostic as we don't have any expected filename */
        CORRADE_COMPARE(flags, TestSuite::ComparisonStatusFlag::Failed);
        Debug d{&out, Debug::Flag::DisableColors};
        compare.printMessage(flags, d, "a", "b");
    }

    CORRADE_COMPARE(Utility::String::replaceFirst(out.str(), DEBUGTOOLS_TEST_DIR, "..."),
        "Actual image a (.../CompareImageCompressed.dds) is compressed, comparison not possible.\n");
}

}}}}

CORRADE_TEST_MAIN(Magnum::DebugTools::Test::CompareImageTest)