diff --git a/briar-android/src/androidTestOfficial/assets/blue-500x500.png b/briar-android/src/androidTestOfficial/assets/blue-500x500.png
new file mode 100644
index 000000000..c7c8cd88f
Binary files /dev/null and b/briar-android/src/androidTestOfficial/assets/blue-500x500.png differ
diff --git a/briar-android/src/androidTestOfficial/assets/green-1000x2000.png b/briar-android/src/androidTestOfficial/assets/green-1000x2000.png
new file mode 100644
index 000000000..b8127e346
Binary files /dev/null and b/briar-android/src/androidTestOfficial/assets/green-1000x2000.png differ
diff --git a/briar-android/src/androidTestOfficial/assets/red-100x100.png b/briar-android/src/androidTestOfficial/assets/red-100x100.png
new file mode 100644
index 000000000..f57e3a1b3
Binary files /dev/null and b/briar-android/src/androidTestOfficial/assets/red-100x100.png differ
diff --git a/briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/AttachmentCreationTaskTest.java b/briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/AttachmentCreationTaskTest.java
new file mode 100644
index 000000000..943644f7c
--- /dev/null
+++ b/briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/AttachmentCreationTaskTest.java
@@ -0,0 +1,67 @@
+package org.briarproject.briar.android.attachment;
+
+import android.content.res.AssetManager;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.logging.Logger;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+
+import static androidx.test.InstrumentationRegistry.getContext;
+import static androidx.test.core.app.ApplicationProvider.getApplicationContext;
+import static java.util.logging.Logger.getLogger;
+
+@RunWith(AndroidJUnit4.class)
+public class AttachmentCreationTaskTest {
+
+	private static Logger LOG =
+			getLogger(AttachmentCreationTaskTest.class.getName());
+
+	private final ImageHelper imageHelper = new ImageHelperImpl();
+	private final ImageSizeCalculator imageSizeCalculator =
+			new ImageSizeCalculator(imageHelper);
+	@SuppressWarnings("ConstantConditions")  // add real objects when needed
+	private final AttachmentCreationTask task = new AttachmentCreationTask(null,
+			getApplicationContext().getContentResolver(), null,
+			imageSizeCalculator, null, null, true);
+
+	@Test
+	public void testCompress() throws Exception {
+		InputStream is = getAssetInputStream("animated.gif");
+		task.compressImage(is, "image/gif");
+
+		is = getAssetInputStream("animated2.gif");
+		task.compressImage(is, "image/gif");
+
+		is = getAssetInputStream("blue-500x500.png");
+		task.compressImage(is, "image/png");
+
+		is = getAssetInputStream("error_high.jpg");
+		task.compressImage(is, "image/jpeg");
+
+		is = getAssetInputStream("error_large.gif");
+		task.compressImage(is, "image/gif");
+
+		is = getAssetInputStream("error_wide.jpg");
+		task.compressImage(is, "image/jpeg");
+
+		is = getAssetInputStream("green-1000x2000.png");
+		task.compressImage(is, "image/png");
+
+		is = getAssetInputStream("red-100x100.png");
+		task.compressImage(is, "image/png");
+	}
+
+	private InputStream getAssetInputStream(String name) throws IOException {
+		LOG.warning("getAssetInputStream: " + name);
+		// pm.getResourcesForApplication(packageName).getAssets() did not work
+		//noinspection deprecation
+		AssetManager assets = getContext().getAssets();
+		return assets.open(name);
+	}
+
+}
diff --git a/briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentCreationTask.java b/briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentCreationTask.java
index cdeea6c5d..f4a46231d 100644
--- a/briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentCreationTask.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentCreationTask.java
@@ -22,6 +22,7 @@ import java.util.Collection;
 import java.util.logging.Logger;
 
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 
 import static android.graphics.Bitmap.CompressFormat.JPEG;
 import static android.graphics.BitmapFactory.decodeStream;
@@ -130,7 +131,8 @@ class AttachmentCreationTask {
 		return false;
 	}
 
-	private InputStream compressImage(InputStream is, String contentType)
+	@VisibleForTesting
+	InputStream compressImage(InputStream is, String contentType)
 			throws IOException {
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
 		try {