RFR: 8342098: Write a test to compare the images [v3]

[Alexey Ivanov]

On Mon, 21 Oct 2024 08:26:54 GMT, Manukumar V S <mvs at openjdk.org> wrote:

>> Naveen Narayanan has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8342098: Updated review comments
>
> test/jdk/java/awt/Robot/ScreenCaptureRobotTest.java line 125:
> 
>> 123:                 capturedPixel = capturedImg.getRGB(i, j);
>> 124:                 realPixel = realImg.getRGB(i, j);
>> 125:                 if (capturedPixel != realPixel) {
> 
> Suggestion:
> 
>                if (capturedPixel != realPixel) {
>                     System.out.println("Captured pixel ("+capturedPixel+") at (" + i + ", " + j + ") is not equal to real pixel (" + realPixel + ")");

Yes, printing the values would absolutely help.

Please, print pixels in hex, it'll make more sense: [`Integer.toHexString`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Integer.html#toHexString(int)).

> test/jdk/java/awt/Robot/ScreenCaptureRobotTest.java line 133:
> 
>> 131:         return result;
>> 132:     }
>> 133: 
> 
> Suggestion:
> 
> //Save BufferedImage to PNG file
>     private static void saveImage(BufferedImage image, String fileName) {
>         if (image != null) {
>             try {
>                 File file = new File(fileName);
>                 System.out.println("Saving button image to " + file.getAbsolutePath());
>                 ImageIO.write(image, "PNG", file);
>             } catch (Exception e) {
>                 throw new RuntimeException("Could not write image file");
>             }
>         } else {
>             throw new RuntimeException("BufferedImage was set to null");
>         }
>     }

Yes, please save the images, especially when comparison fails.

I think handling `image != null` is not needed here. If `null` is passed, the test will fail with `NullPointerException`, and it's acceptable. Without the `if` statement, the code to save the image would be cleaner.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/21524#discussion_r1808850177
PR Review Comment: https://git.openjdk.org/jdk/pull/21524#discussion_r1808864929