Spin event loop to process pending UI updates before checking the pasted

content on the Text.

As content copy/paste works well manually junit fails because junit
checks the text content well before it is updated by GTK. So it is a
timing delay. Processing all the pending events make sure text is
updated(Either by introducing some delay in junit or really processing
any pending UI updates).

see #2491

Author: raghucssit

bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Text.java

@@ -739,7 +739,12 @@ Rectangle computeTrimInPixels (int x, int y, int width, int height) {
  * <p>
  * The current selection is copied to the clipboard.
  * </p>
- *
+ * <p>
+ * <strong>Note:</strong> Copy data to the Clipboard may be asynchronous. This
+ * means that the new clipboard content may not be immediately available right
+ * after calling this method. To ensure the update is visible, use
+ * {@link Display#asyncExec(Runnable)} before accessing the clipboard data.
+ * </p>
  * @exception SWTException <ul>
  *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Text.java

@@ -288,6 +288,11 @@ public void test_copy() {
 
 	text.setText("");
 	text.paste();
+	// Spin the event loop to let GTK process the clipboard + entry update
+	Display display = text.getDisplay();
+	while (display.readAndDispatch()) {
+	    // loop until no more events
+	}
 	assertEquals("00000", text.getText());
 
 	// tests a SINGLE line text editor
@@ -307,6 +312,9 @@ public void test_copy() {
 
 	text.setText("");
 	text.paste();
+	while (display.readAndDispatch()) {
+	    // loop until no more events
+	}
 	assertEquals("00000", text.getText());
 }