Avoid mocking java.lang.Runtime

RELNOTES=n/a
PiperOrigin-RevId: 725318466

Author: cushon

android/guava-tests/test/com/google/common/util/concurrent/UncaughtExceptionHandlersTest.java

@@ -20,6 +20,7 @@
 import static org.mockito.Mockito.verify;
 
 import com.google.common.util.concurrent.UncaughtExceptionHandlers.Exiter;
+import com.google.common.util.concurrent.UncaughtExceptionHandlers.RuntimeWrapper;
 import junit.framework.TestCase;
 import org.jspecify.annotations.NullUnmarked;
 
@@ -29,11 +30,11 @@
 @NullUnmarked
 public class UncaughtExceptionHandlersTest extends TestCase {
 
-  private Runtime runtimeMock;
+  private RuntimeWrapper runtimeMock;
 
   @Override
   protected void setUp() {
-    runtimeMock = mock(Runtime.class);
+    runtimeMock = mock(RuntimeWrapper.class);
   }
 
   public void testExiter() {

android/guava/src/com/google/common/util/concurrent/UncaughtExceptionHandlers.java

@@ -50,16 +50,21 @@ private UncaughtExceptionHandlers() {}
    * process with an exit status of 1, indicating abnormal termination.
    */
   public static UncaughtExceptionHandler systemExit() {
-    return new Exiter(Runtime.getRuntime());
+    return new Exiter(Runtime.getRuntime()::exit);
+  }
+
+  @VisibleForTesting
+  interface RuntimeWrapper {
+    void exit(int status);
   }
 
   @VisibleForTesting
   static final class Exiter implements UncaughtExceptionHandler {
     private static final LazyLogger logger = new LazyLogger(Exiter.class);
 
-    private final Runtime runtime;
+    private final RuntimeWrapper runtime;
 
-    Exiter(Runtime runtime) {
+    Exiter(RuntimeWrapper runtime) {
       this.runtime = runtime;
     }
 

guava-tests/test/com/google/common/util/concurrent/UncaughtExceptionHandlersTest.java

@@ -20,6 +20,7 @@
 import static org.mockito.Mockito.verify;
 
 import com.google.common.util.concurrent.UncaughtExceptionHandlers.Exiter;
+import com.google.common.util.concurrent.UncaughtExceptionHandlers.RuntimeWrapper;
 import junit.framework.TestCase;
 import org.jspecify.annotations.NullUnmarked;
 
@@ -29,11 +30,11 @@
 @NullUnmarked
 public class UncaughtExceptionHandlersTest extends TestCase {
 
-  private Runtime runtimeMock;
+  private RuntimeWrapper runtimeMock;
 
   @Override
   protected void setUp() {
-    runtimeMock = mock(Runtime.class);
+    runtimeMock = mock(RuntimeWrapper.class);
   }
 
   public void testExiter() {

guava/src/com/google/common/util/concurrent/UncaughtExceptionHandlers.java

@@ -50,16 +50,21 @@ private UncaughtExceptionHandlers() {}
    * process with an exit status of 1, indicating abnormal termination.
    */
   public static UncaughtExceptionHandler systemExit() {
-    return new Exiter(Runtime.getRuntime());
+    return new Exiter(Runtime.getRuntime()::exit);
+  }
+
+  @VisibleForTesting
+  interface RuntimeWrapper {
+    void exit(int status);
   }
 
   @VisibleForTesting
   static final class Exiter implements UncaughtExceptionHandler {
     private static final LazyLogger logger = new LazyLogger(Exiter.class);
 
-    private final Runtime runtime;
+    private final RuntimeWrapper runtime;
 
-    Exiter(Runtime runtime) {
+    Exiter(RuntimeWrapper runtime) {
       this.runtime = runtime;
     }