Move scanActualColors to JupiterTestBase and remove duplicates

java/test/org/openqa/selenium/TakesScreenshotTest.java

@@ -326,44 +326,6 @@ private Set<String> generateExpectedColors(
     return colors;
   }
 
-  /**
-   * Get colors from image from each point at grid defined by stepX/stepY.
-   *
-   * @param image - image
-   * @param stepX - interval in pixels b/w point in X dimension
-   * @param stepY - interval in pixels b/w point in Y dimension
-   * @return set of colors in string hex presentation
-   */
-  private Set<String> scanActualColors(BufferedImage image, final int stepX, final int stepY) {
-    Set<String> colors = new TreeSet<>();
-
-    try {
-      int height = image.getHeight();
-      int width = image.getWidth();
-      assertThat(width > 0).isTrue();
-      assertThat(height > 0).isTrue();
-
-      Raster raster = image.getRaster();
-      for (int i = 0; i < width; i = i + stepX) {
-        for (int j = 0; j < height; j = j + stepY) {
-          String hex =
-              String.format(
-                  "#%02x%02x%02x",
-                  (raster.getSample(i, j, 0)),
-                  (raster.getSample(i, j, 1)),
-                  (raster.getSample(i, j, 2)));
-          colors.add(hex);
-        }
-      }
-    } catch (Exception e) {
-      fail("Unable to get actual colors from screenshot: " + e.getMessage());
-    }
-
-    assertThat(colors).isNotEmpty();
-
-    return colors;
-  }
-
   /**
    * Compares sets of colors are same.
    *

java/test/org/openqa/selenium/firefox/TakesFullPageScreenshotTest.java

@@ -23,7 +23,6 @@
 
 import com.google.common.collect.Sets;
 import java.awt.image.BufferedImage;
-import java.awt.image.Raster;
 import java.io.ByteArrayInputStream;
 import java.io.File;
 import java.io.IOException;
@@ -47,7 +46,7 @@
  * coloured areas - take screenshot - calculate expected colors as in tested HTML page - scan
  * screenshot for actual colors * compare
  *
- * @see org.openqa.selenium.TakesScreenshotTest
+ * <p>(See related screenshot tests in the parent package.)
  */
 
 // TODO(user): verify expected behaviour after frame switching
@@ -184,44 +183,6 @@ private Set<String> generateExpectedColors(
     return colors;
   }
 
-  /**
-   * Get colors from image from each point at grid defined by stepX/stepY.
-   *
-   * @param image - image
-   * @param stepX - interval in pixels b/w point in X dimension
-   * @param stepY - interval in pixels b/w point in Y dimension
-   * @return set of colors in string hex presentation
-   */
-  private Set<String> scanActualColors(BufferedImage image, final int stepX, final int stepY) {
-    Set<String> colors = new TreeSet<>();
-
-    try {
-      int height = image.getHeight();
-      int width = image.getWidth();
-      assertThat(width > 0).isTrue();
-      assertThat(height > 0).isTrue();
-
-      Raster raster = image.getRaster();
-      for (int i = 0; i < width; i = i + stepX) {
-        for (int j = 0; j < height; j = j + stepY) {
-          String hex =
-              String.format(
-                  "#%02x%02x%02x",
-                  (raster.getSample(i, j, 0)),
-                  (raster.getSample(i, j, 1)),
-                  (raster.getSample(i, j, 2)));
-          colors.add(hex);
-        }
-      }
-    } catch (Exception e) {
-      fail("Unable to get actual colors from screenshot: " + e.getMessage());
-    }
-
-    assertThat(colors).isNotEmpty();
-
-    return colors;
-  }
-
   /**
    * Compares sets of colors are same.
    *

java/test/org/openqa/selenium/testing/JupiterTestBase.java

@@ -17,12 +17,18 @@
 
 package org.openqa.selenium.testing;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assumptions.assumeThat;
+import static org.junit.jupiter.api.Assertions.fail;
 
+import java.awt.image.BufferedImage;
+import java.awt.image.Raster;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.time.Duration;
 import java.util.Optional;
+import java.util.Set;
+import java.util.TreeSet;
 import java.util.logging.Logger;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeAll;
@@ -116,4 +122,43 @@ public String toLocalUrl(String url) {
   protected WebDriverWait wait(WebDriver driver) {
     return new WebDriverWait(driver, Duration.ofSeconds(10));
   }
+
+  /**
+   * Get colors from image from each point at grid defined by stepX/stepY.
+   *
+   * @param image - image
+   * @param stepX - interval in pixels b/w point in X dimension
+   * @param stepY - interval in pixels b/w point in Y dimension
+   * @return set of colors in string hex presentation
+   */
+  protected final Set<String> scanActualColors(
+      BufferedImage image, final int stepX, final int stepY) {
+    Set<String> colors = new TreeSet<>();
+
+    try {
+      int height = image.getHeight();
+      int width = image.getWidth();
+      assertThat(width > 0).isTrue();
+      assertThat(height > 0).isTrue();
+
+      Raster raster = image.getRaster();
+      for (int i = 0; i < width; i = i + stepX) {
+        for (int j = 0; j < height; j = j + stepY) {
+          String hex =
+              String.format(
+                  "#%02x%02x%02x",
+                  (raster.getSample(i, j, 0)),
+                  (raster.getSample(i, j, 1)),
+                  (raster.getSample(i, j, 2)));
+          colors.add(hex);
+        }
+      }
+    } catch (Exception e) {
+      fail("Unable to get actual colors from screenshot: " + e.getMessage());
+    }
+
+    assertThat(colors).isNotEmpty();
+
+    return colors;
+  }
 }