openseadragon/test/modules/tilecache.js

/* global QUnit, testLog */

(function() {
    const Convertor = OpenSeadragon.convertor,
        T_A = "__TEST__typeA", T_B = "__TEST__typeB", T_C = "__TEST__typeC", T_D = "__TEST__typeD", T_E = "__TEST__typeE";

    let viewer;

    //we override jobs: remember original function
    const originalJob = OpenSeadragon.ImageLoader.prototype.addJob;

    //event awaiting
    function waitFor(predicate) {
        const time = setInterval(() => {
            if (predicate()) {
                clearInterval(time);
            }
        }, 20);
    }

    // Replace conversion with our own system and test: __TEST__ prefix must be used, otherwise
    // other tests will interfere
    let typeAtoB = 0, typeBtoC = 0, typeCtoA = 0, typeDtoA = 0, typeCtoE = 0;
    //set all same costs to get easy testing, know which path will be taken
    Convertor.learn(T_A, T_B, (tile, x) => {
        typeAtoB++;
        return x+1;
    });
    Convertor.learn(T_B, T_C, (tile, x) => {
        typeBtoC++;
        return x+1;
    });
    Convertor.learn(T_C, T_A, (tile, x) => {
        typeCtoA++;
        return x+1;
    });
    Convertor.learn(T_D, T_A, (tile, x) => {
        typeDtoA++;
        return x+1;
    });
    Convertor.learn(T_C, T_E, (tile, x) => {
        typeCtoE++;
        return x+1;
    });
    //'Copy constructors'
    let copyA = 0, copyB = 0, copyC = 0, copyD = 0, copyE = 0;
    //also learn destructors
    Convertor.learn(T_A, T_A,(tile, x) => {
        copyA++;
        return x+1;
    });
    Convertor.learn(T_B, T_B,(tile, x) => {
        copyB++;
        return x+1;
    });
    Convertor.learn(T_C, T_C,(tile, x) => {
        copyC++;
        return x-1;
    });
    Convertor.learn(T_D, T_D,(tile, x) => {
        copyD++;
        return x+1;
    });
    Convertor.learn(T_E, T_E,(tile, x) => {
        copyE++;
        return x+1;
    });
    let destroyA = 0, destroyB = 0, destroyC = 0, destroyD = 0, destroyE = 0;
    //also learn destructors
    Convertor.learnDestroy(T_A, () => {
        destroyA++;
    });
    Convertor.learnDestroy(T_B, () => {
        destroyB++;
    });
    Convertor.learnDestroy(T_C, () => {
        destroyC++;
    });
    Convertor.learnDestroy(T_D, () => {
        destroyD++;
    });
    Convertor.learnDestroy(T_E, () => {
        destroyE++;
    });

    // ----------
    QUnit.module('TileCache', {
        beforeEach: function () {
            $('<div id="example"></div>').appendTo("#qunit-fixture");

            testLog.reset();

            viewer = OpenSeadragon({
                id: 'example',
                prefixUrl: '/build/openseadragon/images/',
                maxImageCacheCount: 200, //should be enough to fit test inside the cache
                springStiffness: 100 // Faster animation = faster tests
            });
            OpenSeadragon.ImageLoader.prototype.addJob = originalJob;

            // Reset counters
            typeAtoB = 0, typeBtoC = 0, typeCtoA = 0, typeDtoA = 0, typeCtoE = 0;
            copyA = 0, copyB = 0, copyC = 0, copyD = 0, copyE = 0;
            destroyA = 0, destroyB = 0, destroyC = 0, destroyD = 0, destroyE = 0;
        },
        afterEach: function () {
            if (viewer && viewer.close) {
                viewer.close();
            }

            viewer = null;
        }
    });

    // ----------
    QUnit.test('basics', function(assert) {
        const done = assert.async();
        const fakeViewer = MockSeadragon.getViewer(
            MockSeadragon.getDrawer({
                // tile in safe mode inspects the supported formats upon cache set
                getSupportedDataFormats() {
                    return [T_A, T_B, T_C, T_D, T_E];
                }
            })
        );
        const fakeTiledImage0 = MockSeadragon.getTiledImage(fakeViewer);
        const fakeTiledImage1 = MockSeadragon.getTiledImage(fakeViewer);

        const tile0 = MockSeadragon.getTile('foo.jpg', fakeTiledImage0);
        const tile1 = MockSeadragon.getTile('foo.jpg', fakeTiledImage1);

        const cache = new OpenSeadragon.TileCache();
        assert.equal(cache.numTilesLoaded(), 0, 'no tiles to begin with');

        tile0._caches[tile0.cacheKey] = cache.cacheTile({
            tile: tile0,
            tiledImage: fakeTiledImage0,
            data: 3,
            dataType: T_A
        });
        tile0._cacheSize++;

        assert.equal(cache.numTilesLoaded(), 1, 'tile count after cache');

        tile1._caches[tile1.cacheKey] = cache.cacheTile({
            tile: tile1,
            tiledImage: fakeTiledImage1,
            data: 55,
            dataType: T_B
        });
        tile1._cacheSize++;
        assert.equal(cache.numTilesLoaded(), 2, 'tile count after second cache');

        cache.clearTilesFor(fakeTiledImage0);

        assert.equal(cache.numTilesLoaded(), 1, 'tile count after first clear');

        cache.clearTilesFor(fakeTiledImage1);

        assert.equal(cache.numTilesLoaded(), 0, 'tile count after second clear');

        done();
    });

    // ----------
    QUnit.test('maxImageCacheCount', function(assert) {
        const done = assert.async();
        const fakeViewer = MockSeadragon.getViewer(
            MockSeadragon.getDrawer({
                // tile in safe mode inspects the supported formats upon cache set
                getSupportedDataFormats() {
                    return [T_A, T_B, T_C, T_D, T_E];
                }
            })
        );
        const fakeTiledImage0 = MockSeadragon.getTiledImage(fakeViewer);
        const tile0 = MockSeadragon.getTile('different.jpg', fakeTiledImage0);
        const tile1 = MockSeadragon.getTile('same.jpg', fakeTiledImage0);
        const tile2 = MockSeadragon.getTile('same.jpg', fakeTiledImage0);

        const cache = new OpenSeadragon.TileCache({
            maxImageCacheCount: 1
        });

        assert.equal(cache.numTilesLoaded(), 0, 'no tiles to begin with');

        tile0._caches[tile0.cacheKey] = cache.cacheTile({
            tile: tile0,
            tiledImage: fakeTiledImage0,
            data: 55,
            dataType: T_B
        });
        tile0._cacheSize++;

        assert.equal(cache.numTilesLoaded(), 1, 'tile count after add');

        tile1._caches[tile1.cacheKey] = cache.cacheTile({
            tile: tile1,
            tiledImage: fakeTiledImage0,
            data: 55,
            dataType: T_B
        });
        tile1._cacheSize++;

        assert.equal(cache.numTilesLoaded(), 1, 'tile count after add of second image');

        tile2._caches[tile2.cacheKey] = cache.cacheTile({
            tile: tile2,
            tiledImage: fakeTiledImage0,
            data: 55,
            dataType: T_B
        });
        tile2._cacheSize++;

        assert.equal(cache.numTilesLoaded(), 2, 'tile count after additional same image');

        done();
    });

    //Tile API and cache interaction
    QUnit.test('Tile API: basic conversion', function(test) {
        const done = test.async();
        const fakeViewer = MockSeadragon.getViewer(
            MockSeadragon.getDrawer({
                // tile in safe mode inspects the supported formats upon cache set
                getSupportedDataFormats() {
                    return [T_A, T_B, T_C, T_D, T_E];
                }
            })
        );
        const tileCache = fakeViewer.tileCache;
        const fakeTiledImage0 = MockSeadragon.getTiledImage(fakeViewer);
        const fakeTiledImage1 = MockSeadragon.getTiledImage(fakeViewer);

        //load data: note that tests SETUP MORE CACHES than they might use: it tests that some other caches / tiles
        // are not touched during the manipulation of unrelated caches / tiles
        const tile00 = MockSeadragon.getTile('foo.jpg', fakeTiledImage0);
        tile00.addCache(tile00.cacheKey, 0, T_A, false, false);
        const tile01 = MockSeadragon.getTile('foo2.jpg', fakeTiledImage0);
        tile01.addCache(tile01.cacheKey, 0, T_B, false, false);
        const tile10 = MockSeadragon.getTile('foo3.jpg', fakeTiledImage1);
        tile10.addCache(tile10.cacheKey, 0, T_C, false, false);
        const tile11 = MockSeadragon.getTile('foo3.jpg', fakeTiledImage1);
        tile11.addCache(tile11.cacheKey, 0, T_C, false, false);
        const tile12 = MockSeadragon.getTile('foo.jpg', fakeTiledImage1);
        tile12.addCache(tile12.cacheKey, 0, T_A, false, false);

        const collideGetSet = async (tile, type) => {
            const value = await tile.getData(type);
            await tile.setData(value, type);
            return value;
        };

        //test set/get data in async env
        (async function() {
            test.equal(tileCache.numTilesLoaded(), 5, "We loaded 5 tiles");
            test.equal(tileCache.numCachesLoaded(), 3, "We loaded 3 cache objects");

            //test structure
            const c00 = tile00.getCache(tile00.cacheKey);
            test.equal(c00.getTileCount(), 2, "Two tiles share key = url = foo.jpg.");
            const c01 = tile01.getCache(tile01.cacheKey);
            test.equal(c01.getTileCount(), 1, "No tiles share key = url = foo2.jpg.");
            const c10 = tile10.getCache(tile10.cacheKey);
            test.equal(c10.getTileCount(), 2, "Two tiles share key = url = foo3.jpg.");
            const c12 = tile12.getCache(tile12.cacheKey);

            //test get/set data A
            let value = await tile00.getData(T_A);
            test.equal(typeAtoB, 0, "No conversion happened when requesting default type data.");
            test.equal(value, 1, "One copy happened: getData creates working cache -> copy.");
            //explicit type
            value = await tile00.getData(T_A);
            test.equal(typeAtoB, 0, "No conversion also for tile sharing the cache.");
            test.equal(value, 1, "No increase in value A, working cache initialized.");

            //copy & set type A
            value = await tile00.getData(T_A);
            test.equal(typeAtoB, 0, "No conversion also for tile sharing the cache.");
            test.equal(copyA, 1, "A copy happened.");
            test.equal(value, 1, "+1 conversion step happened.");
            await tile00.setData(value, T_A); //overwrite
            test.equal(tile00.cacheKey, tile00.originalCacheKey, "Overwriting cache: no change in value.");
            test.equal(c00.type, T_A, "The tile cache data type was unchanged.");
            //convert to B, async + sync behavior
            value = await tile00.getData(T_B);
            await tile00.setData(value, T_B); //overwrite
            test.equal(typeAtoB, 1, "Conversion A->B happened.");
            test.equal(value, 2, "+1 conversion step happened.");
            // shares cache, but it is different tile instance

            value = await tile12.getData(T_B);
            test.equal(typeAtoB, 2, "Conversion A->B happened second time -> working cache forcefully initiated over shared data.");
            test.equal(value, 1, "Original data is 1 since all previous modifications happened over working cache of tile00.");

            //test ASYNC get data
            value = await tile12.getData(T_B);
            await tile12.setData(value, T_B); //overwrite
            test.equal(typeAtoB, 2, "Two working caches created, two conversions.");
            test.equal(typeBtoC, 0, "No conversion happened when requesting default type data.");
            test.equal(copyB, 0, "B type not copied, working cache already initialized.");
            test.equal(value, 1, "Data stayed the same.");

            // Async collisions testing

            //convert to A, before that request conversion to A and B several times, since we copy
            // there should be just exactly the right amount of conversions
            tile12.getData(T_A); // B -> C -> A
            tile12.getData(T_B); // no conversion, all run at the same time
            tile12.getData(T_B); // no conversion, all run at the same time
            tile12.getData(T_A); // B -> C -> A
            tile12.getData(T_B); // no conversion, all run at the same time
            value = await tile12.getData(T_A); // B -> C -> A
            test.equal(typeAtoB, 2, "No conversion A->B.");
            test.equal(typeBtoC, 3, "Conversion B->C happened three times.");
            test.equal(typeCtoA, 3, "Conversion C->A happened three times.");
            test.equal(typeDtoA, 0, "Conversion D->A did not happen.");
            test.equal(typeCtoE, 0, "Conversion C->E did not happen.");
            test.equal(value, 3, "We started from value 1 (wokring cache state), and performed two conversions (B->C->A). " +
                "Any other conversion attempt results were thrown away, cache state does not get updated when conversion takes place, data is copied (by default).");

            // C12 cache is still type A, we modified wokring cache!
            //but direct requests on cache change await all modifications, but are lazy
            //convert to A, before that request conversion to A and B several times, should finish accordingly
            c12.transformTo(T_A); // no-op
            c12.transformTo(T_B); // A -> B
            c12.transformTo(T_B); // no-op
            c12.transformTo(T_A); // B -> C -> A
            c12.transformTo(T_B); // A -> B
            //should finish with next await with 6 steps at this point, add two more and await end
            value = await c12.transformTo(T_A); // B -> C -> A
            test.equal(typeAtoB, 4, "Conversion A->B happened two more times, in total 4.");
            test.equal(typeBtoC, 5, "Conversion B->C happened five (3+2) times.");
            test.equal(typeCtoA, 5, "Conversion C->A happened five (3+2) times.");
            test.equal(typeDtoA, 0, "Conversion D->A did not happen.");
            test.equal(typeCtoE, 0, "Conversion C->E did not happen.");
            test.equal(value, 6, "In total 6 conversions on the cache object.");
            await tile12.setData(value, T_A);
            test.equal(c12.data, 6, "In total 6 conversions on the cache object, above set changes working cache.");
            test.equal(c12.data, 6, "Changing type of working cache fires no conversion, we overwrite cache state.");

            // Get set collide tries to modify the cache: all first request the data, and set the data in random order,
            // but writing is done after reading --> we start from TA
            collideGetSet(tile12, T_A); // no conversion, already in TA
            collideGetSet(tile12, T_B); // conversion to TB
            collideGetSet(tile12, T_B); // no conversion, already in TA
            collideGetSet(tile12, T_A); // conversion to TB
            collideGetSet(tile12, T_B); // conversion to TB
            //should finish with next await with 6 steps at this point, add two more and await end
            value = await collideGetSet(tile12, T_C); // A -> B -> C (forced await)
            test.equal(typeAtoB, 8, "Conversion A->B increased by three + one for the last await.");
            test.equal(typeBtoC, 6, "Conversion B->C + one for the last await.");
            test.equal(typeCtoA, 5, "Conversion C->A did not happen.");
            test.equal(typeDtoA, 0, "Conversion D->A did not happen.");
            test.equal(typeCtoE, 0, "Conversion C->E did not happen.");
            test.equal(value, 8, "6+2 steps (writes are colliding, just single write will happen).");
            const workingc12 = tile12.getCache(tile12._wcKey);
            test.equal(workingc12.type, T_C, "Working cache is really type C.");

            //working cache not shared, even if these two caches share key they have different data now
            value = await tile00.getData(T_C);  // B -> C
            test.equal(typeAtoB, 8, "Conversion A->B nor triggered.");
            test.equal(typeBtoC, 7, "Conversion B->C triggered.");
            const workingc00 = tile00.getCache(tile00._wcKey);
            test.notEqual(workingc00, workingc12, "Underlying working cache is not shared despite tiles share hash key.");

            // now set value with keeping origin
            await tile00.setData(42, T_D);
            const newCache = tile00.getCache(tile00._wcKey);
            await newCache.transformTo(T_C); // D -> A -> B -> C
            test.equal(typeDtoA, 1, "Conversion D->A happens first time.");
            test.equal(tile12.originalCacheKey, tile12.cacheKey, "Related tile not affected.");
            test.equal(tile00.originalCacheKey, tile12.originalCacheKey, "Cache data was modified, original kept.");
            test.equal(tile00.cacheKey, tile12.cacheKey, "Main cache keys not changed.");

            // tile restore has no effect on the result since tile00 gets overwritten by tile12.updateRenderTarget()
            tile00.restore(true);
            // tile 12 changes data both tile 00 and tile 12
            tile12.updateRenderTarget();
            let newMainCache12 = tile12.getCache();
            let newMainCache00 = tile00.getCache();

            test.equal(newMainCache12.data, 8, "Tile 12 main cache value is now 8 as inherited from working cache.");
            test.equal(newMainCache00.data, 8, "Tile 00 also shares the same data as tile 12.");

            tile00.updateRenderTarget();
            test.equal(newMainCache12.data, 8, "No effect in update target.");
            test.equal(newMainCache00.data, 8, "No effect in update target.");
            test.notEqual(tile00.cacheKey, tile00.originalCacheKey, "Tiles have original type.");

            // Overwriting stress test with diff cache (see the same test as above, the same reasoning)
            // but now stress test from clean state (WC initialized with first call)
            tile00.restore(true); //first we call restore so that set/get reads from original cache
            await collideGetSet(tile00, T_C); // tile has no working cache, conversion from original A -> B -> C
            test.equal(await tile00.getData(T_C), 8, "Data is now 8 (6 at original + 2 conversion steps).");

            // initialization of working cache directly as different type
            collideGetSet(tile00, T_B); // C -> A -> B
            collideGetSet(tile00, T_A); // C -> A
            collideGetSet(tile00, T_A); // C -> A
            collideGetSet(tile00, T_C); // no change
            //should finish with next await with 6 steps at this point, add two more and await end
            value = await collideGetSet(tile00, T_B); // C -> A -> B
            test.equal(typeAtoB, 12, "Conversion A->B +3");
            test.equal(typeBtoC, 9, "Conversion B->C +2 (one here, one a bit above)");
            test.equal(typeCtoA, 9, "Conversion C->A +4");
            test.equal(typeDtoA, 1, "Conversion D->A did not happen.");
            test.equal(typeCtoE, 0, "Conversion C->E did not happen.");

            test.equal(value, 10, "6 original + 4 conversions value (last collide get set taken in action, rest values discarded).");

            // tile restore has now effect since we swap order of updates
            tile00.restore(true);
            // tile 12 changes data both tile 00 and tile 12
            tile00.updateRenderTarget();
            newMainCache12 = tile12.getCache();
            newMainCache00 = tile00.getCache();

            test.equal(newMainCache12.data, 6, "Tile data is now 6 since we restored old data from tile00.");
            test.equal(newMainCache12, newMainCache00, "Caches are equal.");

            // we delete tile: original and main cache not freed, working yes
            let cacheSize = tileCache.numCachesLoaded();
            tile00.unload(true);
            test.equal(tile00.getCacheSize(), 0, "No caches left.");
            test.equal(await tile00.getData(T_A), undefined, "No data available.");
            test.equal(tile00.loaded, false, "Tile in off state.");
            test.equal(tile00.loading, false, "Tile no loading state.");
            test.equal(tileCache.numCachesLoaded(), cacheSize, "Tile cache no change since original data shared.");

            // we delete another tile, now original and main caches should be freed too
            tile12.unload(true);
            test.equal(tile12.getCacheSize(), 0, "No caches left.");
            test.equal(await tile12.getData(T_A), undefined, "No data available.");
            test.equal(tile12.loaded, false, "Tile in off state.");
            test.equal(tile12.loading, false, "Tile no loading state.");
            test.equal(tileCache.numCachesLoaded(), cacheSize - 1, "Tile cache shrunken by 1 since tile12 had only original data.");

            done();
        })();
    });

    QUnit.test('Tile API: basic conversion', function(test) {
        const done = test.async();
        const fakeViewer = MockSeadragon.getViewer(
            MockSeadragon.getDrawer({
                // tile in safe mode inspects the supported formats upon cache set
                getSupportedDataFormats() {
                    return [T_A, T_B, T_C, T_D, T_E];
                }
            })
        );
        const tileCache = fakeViewer.tileCache;
        const fakeTiledImage0 = MockSeadragon.getTiledImage(fakeViewer);
        const fakeTiledImage1 = MockSeadragon.getTiledImage(fakeViewer);

        //load data: note that tests SETUP MORE CACHES than they might use: it tests that some other caches / tiles
        // are not touched during the manipulation of unrelated caches / tiles
        const tile00 = MockSeadragon.getTile('foo.jpg', fakeTiledImage0);
        tile00.addCache(tile00.cacheKey, 0, T_A, false, false);
        const tile01 = MockSeadragon.getTile('foo2.jpg', fakeTiledImage0);
        tile01.addCache(tile01.cacheKey, 0, T_B, false, false);
        const tile10 = MockSeadragon.getTile('foo3.jpg', fakeTiledImage1);
        tile10.addCache(tile10.cacheKey, 0, T_C, false, false);
        const tile11 = MockSeadragon.getTile('foo3.jpg', fakeTiledImage1);
        tile11.addCache(tile11.cacheKey, 0, T_C, false, false);
        const tile12 = MockSeadragon.getTile('foo.jpg', fakeTiledImage1);
        tile12.addCache(tile12.cacheKey, 0, T_A, false, false);

        //test set/get data in async env
        (async function() {

            // Tile10 VS Tile11 --> share cache (same key), collision update keeps last call sane
            await tile10.setData(3, T_A);
            await tile11.setData(5, T_C);

            await tile10.updateRenderTarget();

            test.equal(tile10.getCache().data, 3, "Tile 10 data used as main.");
            test.equal(tile11.getCache().data, 3, "Tile 10 data used as main.");
            test.equal(tile11.getCache().type, T_A, "Tile 10 data used as main.");
            await tile11.updateRenderTarget();

            test.equal(tile10.getCache().data, 5, "Tile 11 data used as main.");
            test.equal(tile11.getCache().data, 5, "Tile 11 data used as main.");
            test.equal(tile11.getCache().type, T_C, "Tile 11 data used as main.");

            // Tile10 updated, reset -> OK
            await tile10.setData(42, T_A);
            tile10.restore();
            await tile10.updateRenderTarget();
            test.equal(tile10.getCache().data, 0, "Original data used as main: restore was called.");
            test.equal(tile11.getCache().data, 0);
            test.equal(tile11.getCache().type, T_C);


            // UpdateTarget called on restore data
            await tile11.setData(189, T_D);
            await tile10.setData(-87, T_B);
            tile10.restore();
            await tile11.updateRenderTarget();

            test.equal(tile11.getCache().data, 189, "New data reflected.");
            test.equal(tile10.getCache().data, 189, "New data reflected also on connected tile.");
            await tile10.updateRenderTarget();
            test.equal(tile11.getCache().data, 189, "No effect: restore was called.");
            test.equal(tile10.getCache().data, 189, "No effect: restore was called.");

            let cacheSize = tileCache.numCachesLoaded();
            tile11.unload(true);
            test.equal(tile11.getCacheSize(), 0, "No caches left in tile11.");
            test.equal(tileCache.numCachesLoaded(), cacheSize, "No caches freed: shared with tile12");

            tile10.unload(true);
            test.equal(tile10.getCacheSize(), 0, "No caches left in tile11.");
            test.equal(tileCache.numCachesLoaded(), cacheSize - 2, "Two caches freed.");

            tile01.unload(false);
            test.equal(tileCache.numCachesLoaded(), cacheSize - 2, "No cache freed: zombie cache left.");

            tile00.unload(true);
            test.equal(tileCache.numCachesLoaded(), cacheSize - 2, "No cache freed: shared with tile12.");
            tile12.unload(true);
            test.equal(tileCache.numCachesLoaded(), 1, "One zombie cache left.");

            done();
        })();
    });

    //Tile API and cache interaction
    QUnit.test('Tile API Cache Interaction', function(test) {
        const done = test.async();
        const fakeViewer = MockSeadragon.getViewer(
            MockSeadragon.getDrawer({
                // tile in safe mode inspects the supported formats upon cache set
                getSupportedDataFormats() {
                    return [T_A, T_B, T_C, T_D, T_E];
                }
            })
        );
        const tileCache = fakeViewer.tileCache;
        const fakeTiledImage0 = MockSeadragon.getTiledImage(fakeViewer);
        const fakeTiledImage1 = MockSeadragon.getTiledImage(fakeViewer);

        //load data
        const tile00 = MockSeadragon.getTile('foo.jpg', fakeTiledImage0);
        tile00.addCache(tile00.cacheKey, 0, T_A, false, false);
        const tile01 = MockSeadragon.getTile('foo2.jpg', fakeTiledImage0);
        tile01.addCache(tile01.cacheKey, 0, T_B, false, false);
        const tile10 = MockSeadragon.getTile('foo3.jpg', fakeTiledImage1);
        tile10.addCache(tile10.cacheKey, 0, T_C, false, false);
        const tile11 = MockSeadragon.getTile('foo3.jpg', fakeTiledImage1);
        tile11.addCache(tile11.cacheKey, 0, T_C, false, false);
        const tile12 = MockSeadragon.getTile('foo.jpg', fakeTiledImage1);
        tile12.addCache(tile12.cacheKey, 0, T_A, false, false);

        //test set/get data in async env
        (async function() {
            test.equal(tileCache.numTilesLoaded(), 5, "We loaded 5 tiles");
            test.equal(tileCache.numCachesLoaded(), 3, "We loaded 3 cache objects - three different urls");

            const c00 = tile00.getCache(tile00.cacheKey);
            const c12 = tile12.getCache(tile12.cacheKey);

            //now test multi-cache within tile
            const theTileKey = tile00.cacheKey;
            tile00.setData(42, T_E);
            test.equal(tile00.cacheKey, tile00.originalCacheKey, "Original cache still rendered.");
            test.equal(theTileKey, tile00.originalCacheKey, "Original cache key preserved.");

            tile00.updateRenderTarget();
            test.notEqual(tile00.cacheKey, tile00.originalCacheKey, "New cache rendered.");

            //now add artifically another record
            tile00.addCache("my_custom_cache", 128, T_C);
            test.equal(tileCache.numTilesLoaded(), 5, "We still loaded only 5 tiles.");
            test.equal(tileCache.numCachesLoaded(), 5, "The cache has now 5 items (two new added already).");

            test.equal(c00.getTileCount(), 2, "The cache still has only two tiles attached.");
            test.equal(tile00.getCacheSize(), 3, "The tile has three cache objects (original data, main cache & custom.");
            //related tile not affected
            test.notEqual(tile12.cacheKey, tile12.originalCacheKey, "Original cache change reflected on shared caches.");
            test.equal(tile12.originalCacheKey, theTileKey, "Original cache key also preserved.");
            test.equal(c12.getTileCount(), 2, "The original data cache still has only two tiles attached.");
            test.equal(tile12.getCacheSize(), 2, "Related tile cache has also two caches.");

            //add and delete cache nothing changes (+1 destroy T_C)
            tile00.addCache("my_custom_cache2", 128, T_C);
            tile00.removeCache("my_custom_cache2");
            test.equal(tileCache.numTilesLoaded(), 5, "We still loaded only 5 tiles.");
            test.equal(tileCache.numCachesLoaded(), 5, "The cache has now 5 items.");
            test.equal(tile00.getCacheSize(), 3, "The tile has three cache objects.");

            //delete cache as a zombie  (+0 destroy)
            tile00.addCache("my_custom_cache2", 17, T_D);
            //direct access shoes correct value although we set key!
            const myCustomCache2Data = tile00.getCache("my_custom_cache2").data;
            test.equal(myCustomCache2Data, 17, "Previously defined cache does not intervene.");
            test.equal(tileCache.numCachesLoaded(), 6, "The cache size is 6.");
            //keep zombie
            tile00.removeCache("my_custom_cache2", false);
            test.equal(tileCache.numCachesLoaded(), 6, "The cache is 5 + 1 zombie, no change.");
            test.equal(tile00.getCacheSize(), 3, "The tile has three cache objects.");
            test.equal(tileCache._zombiesLoadedCount, 1, "One zombie.");

            //revive zombie
            tile01.addCache("my_custom_cache2", 18, T_D);
            const myCustomCache2OtherData = tile01.getCache("my_custom_cache2").data;
            test.equal(myCustomCache2OtherData, myCustomCache2Data, "Caches are equal because revived.");
            test.equal(tileCache._cachesLoadedCount, 6, "Zombie revived, original state restored.");
            test.equal(tileCache._zombiesLoadedCount, 0, "No zombies.");

            //again, keep zombie
            tile01.removeCache("my_custom_cache2", false);

            //first create additional cache so zombie is not the youngest
            tile01.addCache("some weird cache", 11, T_A);
            test.ok(tile01.cacheKey === tile01.originalCacheKey, "Custom cache does not touch tile cache keys.");

            //insertion aadditional cache clears the zombie first although it is not the youngest one
            test.equal(tileCache.numCachesLoaded(), 7, "The cache has now 7 items.");
            test.equal(tileCache._cachesLoadedCount, 6, "New cache created -> 5+1.");
            test.equal(tileCache._zombiesLoadedCount, 1, "One zombie remains.");

            //Test CAP
            tileCache._maxCacheItemCount = 7;

            // Zombie destroyed before other caches (+1 destroy T_D)
            tile12.setData(43, T_B);
            test.notEqual(tile12.cacheKey, tile12.originalCacheKey, "Original cache key differs.");
            test.equal(theTileKey, tile12.originalCacheKey, "Original cache key preserved.");
            test.equal(tileCache.numCachesLoaded(), 7, "The cache has now 7 items.");
            test.equal(tileCache._zombiesLoadedCount, 0, "One zombie sacrificed, preferred over living cache.");
            test.notOk([tile00, tile01, tile10, tile11, tile12].find(x => !x.loaded), "All tiles sill loaded since zombie was sacrificed.");

            // test destructors called as expected
            test.equal(destroyA, 0, "No destructors for A called.");
            test.equal(destroyB, 0, "No destructors for B called.");
            test.equal(destroyC, 1, "One destruction for C called.");
            test.equal(destroyD, 1, "One destruction for D called.");
            test.equal(destroyE, 0, "No destructors for E called.");


            //try to revive zombie will fail: the zombie was deleted, we will find new vaue there
            tile01.addCache("my_custom_cache2", -849613, T_C);
            const myCustomCache2RecreatedData = tile01.getCache("my_custom_cache2").data;
            test.notEqual(myCustomCache2RecreatedData, myCustomCache2Data, "Caches are not equal because zombie was killed.");
            test.equal(myCustomCache2RecreatedData, -849613, "Cache data is actually as set to 18.");
            test.equal(tileCache.numCachesLoaded(), 7, "The cache has still 7 items.");

            // some tile has been selected as a sacrifice since we triggered cap control
            test.ok([tile00, tile01, tile10, tile11, tile12].find(x => !x.loaded), "One tile has been sacrificed.");
            done();
        })();
    });

    QUnit.test('Zombie Cache', function(test) {
        const done = test.async();

        //test jobs by coverage: fail if cached coverage not fully re-stored without jobs
        let jobCounter = 0, coverage = undefined;
        OpenSeadragon.ImageLoader.prototype.addJob = function (options) {
            jobCounter++;
            if (coverage) {
                //old coverage of previous tiled image: if loaded, fail --> should be in cache
                const coverageItem = coverage[options.tile.level][options.tile.x][options.tile.y];
                test.ok(!coverageItem, "Attempt to add job for tile that should be already in memory.");
            }
            return originalJob.call(this, options);
        };

        let tilesFinished = 0;
        const tileCounter = function (event) {tilesFinished++;}

        const openHandler = function(event) {
            event.item.allowZombieCache(true);

            viewer.world.removeHandler('add-item', openHandler);
            test.ok(jobCounter === 0, 'Initial state, no images loaded');

            waitFor(() => {
                if (tilesFinished === jobCounter && event.item._fullyLoaded) {
                    coverage = $.extend(true, {}, event.item.coverage);
                    viewer.world.removeAll();
                    return true;
                }
                return false;
            });
        };

        let jobsAfterRemoval = 0;
        const removalHandler = function (event) {
            viewer.world.removeHandler('remove-item', removalHandler);
            test.ok(jobCounter > 0, 'Tiled image removed after 100 ms, should load some images.');
            jobsAfterRemoval = jobCounter;

            viewer.world.addHandler('add-item', reopenHandler);
            viewer.addTiledImage({
                tileSource: '/test/data/testpattern.dzi'
            });
        }

        const reopenHandler = function (event) {
            event.item.allowZombieCache(true);

            viewer.removeHandler('add-item', reopenHandler);
            test.equal(jobCounter, jobsAfterRemoval, 'Reopening image does not fetch any tiles imemdiatelly.');

            waitFor(() => {
                if (event.item._fullyLoaded) {
                    viewer.removeHandler('tile-unloaded', unloadTileHandler);
                    viewer.removeHandler('tile-loaded', tileCounter);
                    coverage = undefined;

                    //console test needs here explicit removal to finish correctly
                    OpenSeadragon.ImageLoader.prototype.addJob = originalJob;
                    done();
                    return true;
                }
                return false;
            });
        };

        const unloadTileHandler = function (event) {
            test.equal(event.destroyed, false, "Tile unload event should not delete with zombies!");
        }

        viewer.world.addHandler('add-item', openHandler);
        viewer.world.addHandler('remove-item', removalHandler);
        viewer.addHandler('tile-unloaded', unloadTileHandler);
        viewer.addHandler('tile-loaded', tileCounter);

        viewer.open('/test/data/testpattern.dzi');
    });

    QUnit.test('Zombie Cache Replace Item', function(test) {
        const done = test.async();

        let jobCounter = 0, coverage = undefined;
        OpenSeadragon.ImageLoader.prototype.addJob = function (options) {
            jobCounter++;
            if (coverage) {
                //old coverage of previous tiled image: if loaded, fail --> should be in cache
                const coverageItem = coverage[options.tile.level][options.tile.x][options.tile.y];
                if (!coverageItem) {
                    console.warn(coverage, coverage[options.tile.level][options.tile.x], options.tile);
                }
                test.ok(!coverageItem, "Attempt to add job for tile data that was previously loaded.");
            }
            return originalJob.call(this, options);
        };

        let tilesFinished = 0;
        const tileCounter = function (event) {tilesFinished++;}

        const openHandler = function(event) {
            event.item.allowZombieCache(true);
            viewer.world.removeHandler('add-item', openHandler);
            viewer.world.addHandler('add-item', reopenHandler);

            waitFor(() => {
                if (tilesFinished === jobCounter && event.item._fullyLoaded) {
                    coverage = $.extend(true, {}, event.item.coverage);
                    viewer.addTiledImage({
                        tileSource: '/test/data/testpattern.dzi',
                        index: 0,
                        replace: true
                    });
                    return true;
                }
                return false;
            });
        };

        const reopenHandler = function (event) {
            event.item.allowZombieCache(true);

            viewer.removeHandler('add-item', reopenHandler);
            waitFor(() => {
                if (event.item._fullyLoaded) {
                    viewer.removeHandler('tile-unloaded', unloadTileHandler);
                    viewer.removeHandler('tile-loaded', tileCounter);

                    //console test needs here explicit removal to finish correctly
                    OpenSeadragon.ImageLoader.prototype.addJob = originalJob;
                    done();
                    return true;
                }
                return false;
            });
        };

        const unloadTileHandler = function (event) {
            test.equal(event.destroyed, false, "Tile unload event should not delete with zombies!");
        }

        viewer.world.addHandler('add-item', openHandler);
        viewer.addHandler('tile-unloaded', unloadTileHandler);
        viewer.addHandler('tile-loaded', tileCounter);

        viewer.open('/test/data/testpattern.dzi');
    });

})();