NativeScript/tests/app/ui/image-cache/image-cache-tests.ts

import * as imageCacheModule from "@nativescript/core/ui/image-cache";
import { ImageSource } from "@nativescript/core/image-source";
import { isAndroid, device } from "@nativescript/core/platform";
import lazy from "@nativescript/core/utils/lazy";

const sdkVersion = lazy(() => parseInt(device.sdkVersion));

export const test_ImageCache_ValidUrl = function (done: (err: Error, res?: string) => void) {
    // see https://github.com/NativeScript/NativeScript/issues/6643
    if (isAndroid && sdkVersion() < 20) {
        done(null);

        return;
    }

    const cache = new imageCacheModule.Cache();
    cache.maxRequests = 5;

    let imgSource: ImageSource;
    const url = "https://github.com/NativeScript.png";
    // Try to read the image from the cache
    const image = cache.get(url);
    if (image) {
        // If present -- use it.
        imgSource = new ImageSource(image);
        done(new Error("The image was found in the cache"));
    }
    else {
        // If not present -- request its download.
        cache.push({
            key: url,
            url: url,
            completed: (image: any, key: string) => {
                if (url === key) {
                    imgSource = new ImageSource(image);
                    console.log("Valid url: ", key);
                    done(null);
                }
            }
        });
    }
};

export const test_ImageCache_NothingAtProvidedUrl = function (done: (err: Error, res?: string) => void) {
    const cache = new imageCacheModule.Cache();
    cache.maxRequests = 5;

    let imgSource: ImageSource;
    const url = "https://github.com/NativeScript-NoImage.png";
    // Try to read the image from the cache
    const image = cache.get(url);
    if (image) {
        // If present -- use it.
        imgSource = new ImageSource(image);
        done(new Error("The image was found in the cache"));
    }
    else {
        // If not present -- request its download.
        cache.push({
            key: url,
            url: url,
            completed: (image: any, key: string) => {
                if (url === key) {
                    imgSource = new ImageSource(image);
                }
                done(new Error("The completed callback was not expected to be called"));
            },
            error: (key: string) => {
                console.log("No image for key: ", key);
                done(null);
            }
        });
    }
};