Change ValueWrapper.create() to not wrap another ValueWrapper

src/main/java/org/opentest4j/ValueWrapper.java

@@ -49,12 +49,16 @@ public final class ValueWrapper implements Serializable {
 	 *
 	 * <p>If the supplied {@code value} is {@code null}, this method will return a
 	 * cached {@code ValueWrapper} suitable for all {@code null} values.
+	 * If the supplied {@code value} is already an instance of {@link ValueWrapper},
+	 * it will be returned as is.
 	 *
 	 * @param value the value to wrap; may be {@code null}
 	 * @return a wrapper for the supplied value; never {@code null}
 	 */
 	public static ValueWrapper create(Object value) {
-		return (value == null ? nullValueWrapper : new ValueWrapper(value));
+		if (value instanceof ValueWrapper)
+			return (ValueWrapper) value;
+		return (value == null) ? nullValueWrapper : new ValueWrapper(value);
 	}
 
 	/**
@@ -66,6 +70,10 @@ public static ValueWrapper create(Object value) {
 	 *
 	 * <p>If the supplied {@code value} is {@code null}, this method will return a
 	 * cached {@code ValueWrapper} suitable for all {@code null} values.
+	 * If the supplied {@code value} is already an instance of {@link ValueWrapper},
+	 * it will be returned as is if the {@code stringRepresentation} match, otherwise
+	 * the original value will be unwrapped and a new {@code ValueWrapper} with the
+	 * new {@code stringRepresentation} will be created.
 	 *
 	 * @param value the value to wrap; may be {@code null}
 	 * @param stringRepresentation a custom rendering of the value; will fallback to
@@ -74,6 +82,11 @@ public static ValueWrapper create(Object value) {
 	 * @since 1.2
 	 */
 	public static ValueWrapper create(Object value, String stringRepresentation) {
+		if (value instanceof ValueWrapper) {
+			ValueWrapper wrapper = (ValueWrapper) value;
+			return wrapper.stringRepresentation.equals(stringRepresentation) ? wrapper
+					: create(wrapper.value, stringRepresentation);
+		}
 		return (value == null ? nullValueWrapper : new ValueWrapper(value, stringRepresentation));
 	}
 

src/test/java/org/opentest4j/ValueWrapperTests.java

@@ -16,11 +16,7 @@
 
 package org.opentest4j;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotEquals;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.*;
 
 import java.io.Serializable;
 
@@ -73,6 +69,33 @@ public void acceptsCustomStringRepresentation() {
 		assertTrue(wrapper.toString().endsWith(")"));
 	}
 
+	@Test
+	public void doesNotWrapAnotherValueWrapper() {
+		ValueWrapper wrapper = ValueWrapper.create(1.2d);
+
+		ValueWrapper same = ValueWrapper.create(wrapper);
+
+		assertSame(wrapper, same);
+	}
+
+	@Test
+	public void doesNotWrapAnotherValueWrapperWithSameCustomRepresentation() {
+		ValueWrapper wrapper = ValueWrapper.create(1.2d, "1,20");
+
+		ValueWrapper same = ValueWrapper.create(wrapper, "1,20");
+
+		assertSame(wrapper, same);
+	}
+
+	@Test
+	public void doesRepackageValueWrapperWithDifferentStringRepresentation() {
+		ValueWrapper wrapper = ValueWrapper.create(1.2d);
+
+		ValueWrapper same = ValueWrapper.create(wrapper, "1,20");
+
+		assertNotSame(wrapper, same);
+	}
+
 	@Test
 	public void nullForCustomStringRepresentationFallsBackToDefaultToString() {
 		ValueWrapper wrapper = ValueWrapper.create(1.2d, null);