Add isPageable method to Pager. (#242)

* Change Pager to use -1 to reflect a 'no items' state.
* Add isPageable method to Pager.

CHANGELOG.md

@@ -6,6 +6,7 @@
 **Bug fixes**
 
 - Fix bug in `Pager` service which occurred when there were no items. [(#237)[https://github.com/elastic/eui/pull/237]]
+- Add `isPageable` method to `Pager` service and set first and last page index to -1 when there are no pages. [(#242)[https://github.com/elastic/eui/pull/242]]
 
 # [`0.0.9`](https://github.com/elastic/eui/tree/v0.0.9)
 

src/services/paging/pager.js

@@ -29,6 +29,8 @@ export class Pager {
     this.update();
   };
 
+  isPageable = () => this.firstItemIndex !== -1;
+
   getTotalPages = () => this.totalPages;
 
   getCurrentPageIndex = () => this.currentPageIndex;
@@ -58,8 +60,8 @@ export class Pager {
     if (this.totalItems <= 0) {
       this.totalPages = 0;
       this.currentPageIndex = 0;
-      this.firstItemIndex = 0;
-      this.lastItemIndex = 0;
+      this.firstItemIndex = -1;
+      this.lastItemIndex = -1;
       return;
     }
 

src/services/paging/pager.test.js

@@ -39,16 +39,37 @@ describe('Pager', () => {
       });
     });
 
+    describe('isPageable', () => {
+      test('returns true when there are pages', () => {
+        expect(pager.isPageable()).toBe(true);
+      });
+
+      test('returns false when there no pages', () => {
+        pager.setTotalItems(0);
+        expect(pager.isPageable()).toBe(false);
+      });
+    });
+
     describe('getFirstItemIndex', () => {
       test('returns first item index', () => {
         expect(pager.getFirstItemIndex()).toBe(3);
       });
+
+      test('defaults to -1 when there are no items', () => {
+        pager.setTotalItems(0);
+        expect(pager.getFirstItemIndex()).toBe(-1);
+      });
     });
 
     describe('getLastItemIndex', () => {
       test('returns last item index', () => {
         expect(pager.getLastItemIndex()).toBe(5);
       });
+
+      test('defaults to -1 when there are no items', () => {
+        pager.setTotalItems(0);
+        expect(pager.getLastItemIndex()).toBe(-1);
+      });
     });
 
     describe('hasNextPage', () => {
@@ -140,15 +161,6 @@ describe('Pager', () => {
 
   describe('behavior', () => {
     describe('when there are no items', () => {
-      test('getFirstItemIndex defaults to 0', () => {
-        const pager = new Pager(0, 20);
-        expect(pager.getFirstItemIndex()).toBe(0);
-      });
-
-      test('getLastItemIndex defaults to 0', () => {
-        const pager = new Pager(0, 20);
-        expect(pager.getLastItemIndex()).toBe(0);
-      });
     });
   });
 });