fix for issue #223

assertj-swing/src/main/java/org/assertj/swing/edt/CheckThreadViolationRepaintManager.java

@@ -37,6 +37,10 @@
  *         https://swinghelper.dev.java.net/
  */
 abstract class CheckThreadViolationRepaintManager extends RepaintManager {
+  // Should always be turned on because it shouldn't matter
+  // whether the component is showing (realized) or not.
+  // This flag exists only for historical reasons, see
+  // https://stackoverflow.com/questions/491323/is-it-safe-to-construct-swing-awt-widgets-not-on-the-event-dispatch-thread
   private final boolean completeCheck;
 
   private WeakReference<JComponent> lastComponent;
@@ -62,14 +66,24 @@ public void addDirtyRegion(JComponent component, int x, int y, int w, int h) {
     super.addDirtyRegion(component, x, y, w, h);
   }
 
+  /**
+   * Rules enforced by this method:
+   * (1) it is always OK to reach this method on the Event Dispatch Thread.
+   * (2) it is generally not OK to reach this method outside the Event Dispatch Thread.
+   * (3) (exception form rule 2) except when we get here from a repaint() call, because repaint() is thread-safe
+   * (4) (exception from rule 3) it is not OK if swing code calls repaint() outside the EDT, because swing code should be called on the EDT.
+   * (5) (exception from rule 4) using SwingWorker subclasses should not be considered swing code.
+   */
   private void checkThreadViolations(@Nonnull JComponent c) {
     if (!isEventDispatchThread() && (completeCheck || c.isShowing())) {
       boolean imageUpdate = false;
       boolean repaint = false;
-      boolean fromSwing = false;
+      boolean fromSwing = false; // whether we were in a swing method before before the repaint() call
       StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();
       for (StackTraceElement st : stackTrace) {
-        if (repaint && st.getClassName().startsWith("javax.swing.")) {
+        if (repaint
+                && st.getClassName().startsWith("javax.swing.")
+                && !st.getClassName().startsWith("javax.swing.SwingWorker")) {
           fromSwing = true;
         }
         if (repaint && "imageUpdate".equals(st.getMethodName())) {

assertj-swing/src/test/java/org/assertj/swing/edt/FailOnThreadViolationRepaintManager_issue223_Test.java

@@ -0,0 +1,62 @@
+/**
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ *
+ * Copyright 2018 the original author or authors.
+ */
+package org.assertj.swing.edt;
+
+import org.junit.Test;
+
+import javax.swing.*;
+import java.awt.EventQueue;
+import java.lang.reflect.InvocationTargetException;
+import java.util.concurrent.ExecutionException;
+
+import static org.junit.Assert.fail;
+
+/**
+ * See https://github.com/joel-costigliola/assertj-swing/issues/223
+ */
+public class FailOnThreadViolationRepaintManager_issue223_Test {
+  /**
+   * This test fails with the original code, and passes with the fixed code
+   */
+  @Test
+  public void calling_repaint_with_SwingWorker_should_not_be_EDT_Access_Violation() {
+    FailOnThreadViolationRepaintManager.install();
+
+    Runnable edtTask = () -> {
+      JLabel label = new JLabel("Test");
+      SwingWorker notEDTTask = new SwingWorker() {
+        @Override
+        protected Object doInBackground() {
+          // it is OK to call repaint() from here
+          // because repaint() is thread-safe
+          label.repaint();
+          return null;
+        }
+      };
+      notEDTTask.execute();
+      try {
+        // blocks until the doInBackground() method returns
+        notEDTTask.get();
+      } catch (InterruptedException | ExecutionException e) {
+        e.printStackTrace();
+        fail();
+      }
+    };
+    try {
+      EventQueue.invokeAndWait(edtTask);
+    } catch (InterruptedException | InvocationTargetException e) {
+      e.printStackTrace();
+      fail();
+    }
+  }
+}