Screenshot based Testing

A lot of E2E scenarios exceed the capabilities of browsers and webdrivers. This might include common use-cases like a drag and drop from the host system to a webpage or exporting a report into a spreadsheet or PDF-format. In these cases, your web-based tests can be extended to also validate behavior and invoke interactions outside the browser, all within a single test.

Of course, you can also use Sakulis native testing power on its own, e.g. rich-client testing of SAP, office or proprietary software systems. Sakuli accomplishes its native capabilities by scanning the whole screen (or a dedicated region) on a stand-alone computer or in headless container screens, searching for provided image patterns.

Screenshot based actions are relying on an abstract Region class, which represents an abstract region on the desktop. When creating a new instance without parameters, a Region spans over the whole desktop. But, it is also possible to create new regions by specifying left, top, width and height parameters.

The following example represents a test which drags a source element to a target region. In this demo scenario, both source and target are both located on screen via template image. To reproduce this scenario, you need to capture screenshots of the egg and the pan.

(async () => {
    const testCase = new TestCase("native_keyboard_demo");
    const url = "https://codepen.io/naturalhanglider/full/jQMWoq";
    const screen = new Region();
    const env = new Environment();
    try {
        await _navigateTo(url);
        await env.setSimilarity(0.8);
        await screen
            .find("source_egg.png")
            .mouseMove()
            .dragAndDropTo(
                await screen.find("target_pan.png")
            );
        await _wait(3000);
    } catch (e) {
        await testCase.handleException(e);
    } finally {
        testCase.saveResult();
    }
})();

The dragAndDropTo(...) methods always move straight to the target region. In order to follow a more complex path, it is also possible to perform the drag gesture manually. Once the source image has been located on the screen, Sakuli moves the mouse to its location, presses and holds the left mouse button. Afterwards, it locates the target image, moves the mouse there while still holding the mouse button and releases it, once it reaches the target location. To reproduce this scenario, you need to capture screenshots of the egg and the pan.

(async () => {
    const testCase = new TestCase("native_demo");
    const url = "https://codepen.io/naturalhanglider/full/jQMWoq";
    const screen = new Region();
    const env = new Environment();
    try {
        await _navigateTo(url);
        await env.setSimilarity(0.8);
        await screen
            .find("source_egg.png")
            .mouseMove()
            .mouseDown(MouseButton.LEFT)
            .setX(0)
            .setY(0)
            .mouseMove()
            .move(200, 700)
            .mouseMove();
        await screen.find("target_pan.png")
            .mouseMove()
            .mouseUp(MouseButton.LEFT);
        await _wait(3000);
    } catch (e) {
        await testCase.handleException(e);
    } finally {
        testCase.saveResult();
    }
})();

How to Control the Mouse in a Sakuli Test

Sakuli provides two ways to steer mouse movement. Either via coordinates, or via screenshot data. In order to search for image data on your screen you have to instantiate a Region spanning the entire display to access it’s image content.

Moving the mouse to a screenshot

To find a screenshot on the screen, you can use find or waitForImage. With waitForImage you can specify a timeout in which Sakuli continuously searches for the screenshot. This is useful, when e.g. starting a program like excel.

const screen = new Region();
await screen.find("search_this_screenshot.jpg")
    .mouseMove();
    
//searches the screen for 5 seconds for the excel homescreen
await screen.waitForImage("excel_homescreen.jpg", 5000)
    .mouseMove();

find and waitForImage will return a Region for matched screenshots, so chaining as follows might not work, if the second screenshot is not within the Region of the first one.

const screen = new Region();
await screen.find("google_search.png")
    .mouseMove()
    .find("browser_address_bar.jpg")
    .mouseMove();

To get around this problem, you can use left(range), right(range), above(range) or below(range), which returns a new Region. left(range) return a Region that is left of the current region’s border with a width of range, so it does not include the current Region. right, below and above behaves equivalently.

const screen = new Region();
await new Region(500, 500, 100, 100).left(200)
//this returns a new region with (300/500/200/100)

You can also manipulate the current Region with setX(number), setY(number), setH(number), setW(number) or grow(range). With grow you can expand the current region with range px in all four directions.

await screen = new Region();
await new Region(500, 500, 100, 100).grow(100);
//this returns a new region with (400, 400, 300,300)

Moving the mouse relative to current position

One way to change a Region’s position is to use the move(x, y) method. This allows us to shift a region in x and / or y direction, e.g.

const screen = new Region();
await screen.find("login_mask.png")
    .mouseMove()
    .click()
    .type("MyUsername")
    //shifts the region 50px down to e.g. a password field
    .move(0,50)
    //moves the mouse according to the shifted region
    .mouseMove()
    .click()
    .type("MyPassword")
    //shifts the region 50px down and 50px to the right and moves the mouse to e.g. the login button
    .move(50,50)
    .mouseMove()
    .click();
})();

Moving the Mouse to an Absolute Position

Due to the fact that mouseMove() always moves the mouse to the center of a region, we need to instantiate a region with a height and width of 1.

const screen = new Region();
await new Region(100, 200, 1, 1).mouseMove();
//moves the mouse cursor to (100/200)

Drag And Drop

There are two ways to use drag and drop. Firstly, you can use dragAndDropTo(), which drags from one point to another.

const screen = new Region();
await screen.find("drag_mouse_start.png").mouseMove().dragAndDropTo(new Region(200,200,1,1));

await new Region(300,300,1,1).mouseMove().dragAndDropTo(new Region(1000, 1000, 1, 1));

await new Region(0,0,1,1).mouseMove().dragAndDropTo(await screen.find("drag_mouse_end.png"));

Using mouseDown/mouseUp allows us to drag and drop over multiple locations.

const screen = new Region();
await screen.find("drag_mouse_start.png")
    .mouseMove()
    .mouseDown(MouseButton.LEFT)
    .move(200,200)
    .mouseMove()
    .move(-100, -100)
    .mouseMove()
    .mouseUp(MouseButton.LEFT);

mouseUp/mouseDown can be used with either MouseButton.LEFT, MouseButton.MIDDLE or MouseButton.RIGHT.

Region also provides methods to use the keyboards, which also are implemented by Environment. This allows for easy chaining, like

const screen = new Region();
await screen.find("google_search.png")
    .mouseMove()
    .click()
    .type("sakuli.io")
    //moves to the search button
    .move(-100, 100)
    .mouseMove()
    .click()
    .sleepMs(1000)
    //moves to the first search result
    .move(-400,100)
    .click();