Improve LaunchConfigurationTabGroupViewerTest

Add some tests to check that no unnecessary de/activation of tabs is
happening and add some assertions to existing tests too. These
improvements are necessary in order to guarantee that fixing
eclipse-platform/eclipse.platform.swt#46 do
not change the existing behavior of LaunchConfigurationTabGroupViewer.

Contributes to
eclipse-platform#859
Contributes to
eclipse-platform/eclipse.platform.swt#46

debug/org.eclipse.debug.tests/src/org/eclipse/debug/tests/ui/LaunchConfigurationTabGroupViewerTest.java

@@ -70,7 +70,21 @@ public void testAllTabsAreInitializedByDefault() {
 		final ILaunchConfigurationTab[] tabs = runOnDialog(createAndSelect1LaunchConfig);
 
 		for (ILaunchConfigurationTab tab : tabs) {
-			assertThat(((SpyTab) tab)).matches(SpyTab::isInitialized, "should have been initialized");
+			assertThat(((SpyTab) tab)).matches(SpyTab::isInitializedExactlyOnce, "should have been initialized exactly once");
+		}
+	}
+
+	@Test
+	public void testNoTabsAreDeactivatedByDefault() {
+		// Create a launch configuration with a unique name
+		ThrowingRunnable<CoreException> createAndSelect1LaunchConfig = () -> {
+			fLaunchConfigurationsDialog.getTabViewer().setInput(createLaunchConfigurationInstance());
+		};
+
+		final ILaunchConfigurationTab[] tabs = runOnDialog(createAndSelect1LaunchConfig);
+
+		for (ILaunchConfigurationTab tab : tabs) {
+			assertThat(((SpyTab) tab)).matches(not(SpyTab::isDeactivated), "should NOT have been deactivated");
 		}
 	}
 
@@ -82,7 +96,29 @@ public void testFirstTabIsActivatedByDefault() {
 		};
 
 		final ILaunchConfigurationTab[] tabs = runOnDialog(createAndSelect1LaunchConfig);
-		assertThat(((SpyTab) tabs[0])).matches(SpyTab::isActivated, "should have been activated");
+		SpyTab defaultTab = (SpyTab) tabs[0];
+		assertThat(defaultTab).matches(SpyTab::isActivatedExactlyOnce, "should have been activated exactly once");
+		assertThat(defaultTab).matches(not(SpyTab::isDeactivated), "should NOT have been deactivated");
+	}
+
+	@Test
+	public void testActivatingTabTwiceDoesNotDeactivateIt() {
+		int tabIndex = 1;
+
+		// Create a launch configuration with a unique name
+		ThrowingRunnable<CoreException> createAndSelect1LaunchConfig = () -> {
+			fLaunchConfigurationsDialog.getTabViewer().setInput(createLaunchConfigurationInstance());
+
+			// Activate the same tab twice
+			fLaunchConfigurationsDialog.getTabViewer().setActiveTab(tabIndex);
+			fLaunchConfigurationsDialog.getTabViewer().setActiveTab(tabIndex);
+		};
+
+		final ILaunchConfigurationTab[] tabs = runOnDialog(createAndSelect1LaunchConfig);
+
+		SpyTab activeTab = (SpyTab) tabs[tabIndex];
+		assertThat(activeTab).matches(SpyTab::isActivatedExactlyOnce, "should have been activated exactly once");
+		assertThat(activeTab).matches(not(SpyTab::isDeactivated), "should NOT have been deactivated");
 	}
 
 	@Test
@@ -104,6 +140,12 @@ public void testOtherTabInOtherConfigIsActivated() {
 		final ILaunchConfigurationTab[] tabs = runOnDialog(setActiveTab);
 
 		assertThat(((SpyTab) tabs[0])).matches(not(SpyTab::isActivated), "should not have been activated");
+
+		// No tab should have been deactivated in the 2nd configuration
+		for (ILaunchConfigurationTab tab : tabs) {
+			assertThat(((SpyTab) tab)).matches(not(SpyTab::isDeactivated), "should not have been deactivated");
+		}
+
 		assertThat(((SpyTab) tabs[secondTabIndex])).matches(SpyTab::isActivated, "should have been activated");
 	}
 

debug/org.eclipse.debug.tests/src/org/eclipse/debug/tests/ui/SpyTab.java

@@ -22,12 +22,13 @@
  */
 public abstract class SpyTab extends AbstractLaunchConfigurationTab {
 
-	private boolean initialized;
-	private boolean activated;
+	private int initializedCount;
+	private int activatedCount;
+	private int deactivatedCount;
 
 	@Override
 	public String toString() {
-		return getClass().getSimpleName() + " [initialized=" + initialized + ", activated=" + activated + "]";
+		return getClass().getSimpleName() + " [initializedCount=" + initializedCount + ", activatedCount=" + activatedCount + ", deactivatedCount=" + deactivatedCount + "]";
 	}
 
 	@Override
@@ -41,12 +42,12 @@ public String getName() {
 
 	@Override
 	public void initializeFrom(ILaunchConfiguration configuration) {
-		initialized = true;
+		++initializedCount;
 	}
 
 	@Override
 	public void activated(ILaunchConfigurationWorkingCopy workingCopy) {
-		activated = true;
+		++activatedCount;
 	}
 
 	@Override
@@ -58,11 +59,27 @@ public void setDefaults(ILaunchConfigurationWorkingCopy configuration) {
 	}
 
 	public boolean isInitialized() {
-		return initialized;
+		return initializedCount > 0;
+	}
+
+	public boolean isInitializedExactlyOnce() {
+		return initializedCount == 1;
 	}
 
 	public boolean isActivated() {
-		return activated;
+		return activatedCount > 0;
+	}
+
+	public boolean isActivatedExactlyOnce() {
+		return activatedCount == 1;
+	}
+
+	public boolean isDeactivated() {
+		return deactivatedCount > 0;
+	}
+
+	public boolean isDeactivatedExactlyOnce() {
+		return deactivatedCount == 1;
 	}
 
 	// These are necessary because I need several tabs in the launch config and