Add JUnitSystem.exit() back

src/main/java/org/junit/internal/JUnitSystem.java

@@ -3,5 +3,12 @@
 import java.io.PrintStream;
 
 public interface JUnitSystem {
+
+    /**
+     * Will be removed in the next major release
+     */
+    @Deprecated
+    void exit(int code);
+
     PrintStream out();
 }

src/main/java/org/junit/internal/RealSystem.java

@@ -3,6 +3,15 @@
 import java.io.PrintStream;
 
 public class RealSystem implements JUnitSystem {
+
+    /**
+     * Will be removed in the next major release
+     */
+    @Deprecated
+    public void exit(int code) {
+        System.exit(code);
+    }
+
     public PrintStream out() {
         return System.out;
     }

src/test/java/org/junit/tests/TestSystem.java

@@ -8,13 +8,22 @@
 
 public class TestSystem implements JUnitSystem {
     private PrintStream out;
+    public int fCode;
     private ByteArrayOutputStream fOutContents;
 
     public TestSystem() {
         fOutContents = new ByteArrayOutputStream();
         out = new PrintStream(fOutContents);
     }
 
+    /**
+     * Will be removed in the next major release
+     */
+    @Deprecated
+    public void exit(int code) {
+        fCode = code;
+    }
+
     public PrintStream out() {
         return out;
     }