test/lib/jdk/test/lib/Utils.java

@@ -38,22 +38,26 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
+import java.util.Map;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Objects;
 import java.util.Random;
 import java.util.function.BooleanSupplier;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import jdk.internal.misc.Unsafe;
 
-import jdk.test.lib.process.*;
 import static jdk.test.lib.Asserts.assertTrue;
+import jdk.test.lib.process.ProcessTools;
+import jdk.test.lib.process.OutputAnalyzer;
 
 /**
  * Common library for various test helper functions.
  */
 public final class Utils {

@@ -445,10 +449,27 @@
         }
         return iterator.next();
     }
 
     /**
+     * Returns random element of non empty array
+     *
+     * @param <T> a type of array element
+     * @param array array of elements
+     * @return random element of array
+     * @throws IllegalArgumentException if array is empty
+     */
+    public static <T> T getRandomElement(T[] array)
+            throws IllegalArgumentException {
+        if (array == null || array.length == 0) {
+            throw new IllegalArgumentException("Empty or null array");
+        }
+        Random random = getRandomInstance();
+        return array[random.nextInt(array.length)];
+    }
+
+    /**
      * Wait for condition to be true
      *
      * @param condition, a condition to wait for
      */
     public static final void waitForCondition(BooleanSupplier condition) {

@@ -634,7 +655,40 @@
         if (!type.isArray()) {
             return "L" + result + ";";
         }
         return result;
     }
+
+    public static Object[] getNullValues(Class<?>... types) {
+        Object[] result = new Object[types.length];
+        int i = 0;
+        for (Class<?> type : types) {
+            result[i++] = NULL_VALUES.get(type);
+        }
+        return result;
+    }
+    private static Map<Class<?>, Object> NULL_VALUES = new HashMap<>();
+    static {
+        NULL_VALUES.put(boolean.class, false);
+        NULL_VALUES.put(byte.class, (byte) 0);
+        NULL_VALUES.put(short.class, (short) 0);
+        NULL_VALUES.put(char.class, '\0');
+        NULL_VALUES.put(int.class, 0);
+        NULL_VALUES.put(long.class, 0L);
+        NULL_VALUES.put(float.class, 0.0f);
+        NULL_VALUES.put(double.class, 0.0d);
+    }
+
+    /**
+     * Returns mandatory property value
+     * @param propName is a name of property to request
+     * @return a String with requested property value
+     */
+    public static String getMandatoryProperty(String propName) {
+        Objects.requireNonNull(propName, "Requested null property");
+        String prop = System.getProperty(propName);
+        Objects.requireNonNull(prop,
+                String.format("A mandatory property '%s' isn't set", propName));
+        return prop;
+    }
 }