Fix tests in LaunchConfigurationTabGroupViewerTest eclipse-platform#1075

- Remove invalid usages of java.util.function.Predicate.not
- Change assertions in testOnlyDefaultTabInOtherConfigIsActivated and
reactivate the test
- Replace calls to assertj's "matches" method with calls to
isTrue/isFalse to improve readability (also, some calls were wrong)

Fixes eclipse-platform#1075

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

@@ -11,7 +11,6 @@
 
 package org.eclipse.debug.tests.ui;
 
-import static java.util.function.Predicate.not;
 import static org.assertj.core.api.Assertions.assertThat;
 
 import java.util.Arrays;
@@ -31,7 +30,6 @@
 import org.eclipse.debug.ui.ILaunchConfigurationTabGroup;
 import org.eclipse.swt.widgets.Display;
 import org.junit.Before;
-import org.junit.Ignore;
 import org.junit.Test;
 
 public class LaunchConfigurationTabGroupViewerTest {
@@ -71,7 +69,7 @@ public void testAllTabsAreInitializedByDefault() {
 		final ILaunchConfigurationTab[] tabs = runOnDialog(createAndSelect1LaunchConfig);
 
 		for (int i = 0; i < tabs.length; i++) {
-			assertThat(((SpyTab) tabs[i])).withFailMessage("tab %s was not initialized", i).matches(SpyTab::isInitialized);
+			assertThat(((SpyTab) tabs[i]).isInitialized()).withFailMessage("tab %s was not initialized", i).isTrue();
 		}
 	}
 
@@ -83,7 +81,7 @@ public void testFirstTabIsActivatedByDefault() {
 		};
 
 		final ILaunchConfigurationTab[] tabs = runOnDialog(createAndSelect1LaunchConfig);
-		assertThat(((SpyTab) tabs[0])).matches(SpyTab::isActivated, "is activated");
+		assertThat(((SpyTab) tabs[0]).isActivated()).withFailMessage("tab was not activated").isTrue();
 	}
 
 	@Test
@@ -104,12 +102,11 @@ public void testOtherTabInOtherConfigIsActivated() {
 
 		final ILaunchConfigurationTab[] tabs = runOnDialog(setActiveTab);
 
-		assertThat((SpyTab) tabs[0]).withFailMessage("the 1st tab of the other launch configuration shouldn't have been activated").matches(not(SpyTab::isActivated));
-		assertThat((SpyTab) tabs[secondTabIndex]).matches(SpyTab::isActivated, "is activated");
+		assertThat(((SpyTab) tabs[0]).isActivated()).withFailMessage("the 1st tab of the other launch configuration shouldn't have been activated").isFalse();
+		assertThat(((SpyTab) tabs[secondTabIndex]).isActivated()).withFailMessage("the other tab of the other launch configuration should have been activated").isTrue();
 	}
 
 	@Test
-	@Ignore("https://github.com/eclipse-platform/eclipse.platform/issues/1075")
 	public void testOnlyDefaultTabInOtherConfigIsActivated() {
 		int overflowTabIndex = Integer.MAX_VALUE;
 
@@ -127,11 +124,11 @@ public void testOnlyDefaultTabInOtherConfigIsActivated() {
 
 		final ILaunchConfigurationTab[] tabs = runOnDialog(setActiveTab);
 
-		assertThat(((SpyTab) tabs[0])).withFailMessage("the 1st tab of the other launch configuration should have been activated").matches(SpyTab::isActivated);
+		assertThat(((SpyTab) tabs[0]).isActivated()).withFailMessage("the 1st tab of the other launch configuration should have been activated").isTrue();
 
-		// All other tabs should not have been initialized
+		// All other tabs should not have been activated
 		for (int i = 1; i < tabs.length; i++) {
-			assertThat((SpyTab) tabs[i]).withFailMessage("tab %s should not have been initialized", i).matches(not(SpyTab::isInitialized));
+			assertThat(((SpyTab) tabs[i]).isActivated()).withFailMessage("tab %s should not have been activated", i).isFalse();
 		}
 	}
 
@@ -149,7 +146,7 @@ public void testOtherTabIsActivated() {
 
 		final ILaunchConfigurationTab[] tabs = runOnDialog(setActiveTab);
 
-		assertThat((SpyTab) tabs[secondTabIndex]).matches(SpyTab::isActivated, "is activated");
+		assertThat(((SpyTab) tabs[secondTabIndex]).isActivated()).withFailMessage("tab %s should have been activated", secondTabIndex).isTrue();
 	}
 
 	private ILaunchConfigurationWorkingCopy createLaunchConfigurationInstance() throws CoreException {