#89 - Tweaked assertions in PageMetadata.

PageMetadata doesn't reject empty pages anymore if they're used with 1-indexed Pageables. Also tweaked the assertions to only reject negative values for now.

src/main/java/org/springframework/hateoas/PagedResources.java

@@ -204,8 +204,10 @@ public class PagedResources<T> extends Resources<T> {
 		 */
 		public PageMetadata(long size, long number, long totalElements, long totalPages) {
 
-			Assert.isTrue(number < totalPages,
-					"The current page number cannot be greater or equal to the total number of pages!");
+			Assert.isTrue(size > -1, "Size must not be negative!");
+			Assert.isTrue(number > -1, "Number must not be negative!");
+			Assert.isTrue(totalElements > -1, "Total elements must not be negative!");
+			Assert.isTrue(totalPages > -1, "Total pages must not be negative!");
 
 			this.size = size;
 			this.number = number;
@@ -221,7 +223,7 @@ public class PagedResources<T> extends Resources<T> {
 		 * @param totalElements the total number of elements available
 		 */
 		public PageMetadata(long size, long number, long totalElements) {
-			this(size, number, totalElements, totalElements / size);
+			this(size, number, totalElements, size == 0 ? 0 : totalElements / size);
 		}
 
 		/**

src/test/java/org/springframework/hateoas/PagedResourcesUnitTest.java

@@ -55,4 +55,44 @@ public class PagedResourcesUnitTest {
 
 		assertThat(resources.getPreviousLink(), is(notNullValue()));
 	}
+
+	/**
+	 * @see #89
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void preventsNegativePageSize() {
+		new PageMetadata(-1, 0, 0);
+	}
+
+	/**
+	 * @see #89
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void preventsNegativePageNumber() {
+		new PageMetadata(0, -1, 0);
+	}
+
+	/**
+	 * @see #89
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void preventsNegativeTotalElements() {
+		new PageMetadata(0, 0, -1);
+	}
+
+	/**
+	 * @see #89
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void preventsNegativeTotalPages() {
+		new PageMetadata(0, 0, 0, -1);
+	}
+
+	/**
+	 * @see #89
+	 */
+	@Test
+	public void allowsOneIndexedPages() {
+		new PageMetadata(10, 1, 0);
+	}
 }