Add next/prev links to the diff view

Bug: Issue 4514
Change-Id: I39927b397fda8d6bb80b7e3a9144e5cfe620fb5a

polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html

diff --git a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html
index c9c27c5..979ed55 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html
@@ -344,6 +344,52 @@
       assert.equal(linkEls[2].getAttribute('href'), '/c/42/5..10/wheatley.md');
     });
 
+    test('prev/next links', function() {
+      element._changeNum = '42';
+      element._patchRange = {
+        basePatchNum: 'PARENT',
+        patchNum: '10',
+      };
+      element._fileList = ['chell.go', 'glados.txt', 'wheatley.md'];
+      element._path = 'glados.txt';
+      flushAsynchronousOperations();
+      var linkEls = Polymer.dom(element.root).querySelectorAll('.navLink');
+      assert.equal(linkEls.length, 2);
+      assert.equal(linkEls[0].getAttribute('href'), '/c/42/10/chell.go');
+      assert.equal(linkEls[1].getAttribute('href'), '/c/42/10/wheatley.md');
+      element._path = 'wheatley.md';
+      flushAsynchronousOperations();
+      assert.equal(linkEls[0].getAttribute('href'), '/c/42/10/glados.txt');
+      assert.isFalse(linkEls[1].hasAttribute('href'));
+      element._path = 'chell.go';
+      flushAsynchronousOperations();
+      assert.isFalse(linkEls[0].hasAttribute('href'));
+      assert.equal(linkEls[1].getAttribute('href'), '/c/42/10/glados.txt');
+    });
+
+    test('prev/next links with patch range', function() {
+      element._changeNum = '42';
+      element._patchRange = {
+        basePatchNum: '5',
+        patchNum: '10',
+      };
+      element._fileList = ['chell.go', 'glados.txt', 'wheatley.md'];
+      element._path = 'glados.txt';
+      flushAsynchronousOperations();
+      var linkEls = Polymer.dom(element.root).querySelectorAll('.navLink');
+      assert.equal(linkEls.length, 2);
+      assert.equal(linkEls[0].getAttribute('href'), '/c/42/5..10/chell.go');
+      assert.equal(linkEls[1].getAttribute('href'), '/c/42/5..10/wheatley.md');
+      element._path = 'wheatley.md';
+      flushAsynchronousOperations();
+      assert.equal(linkEls[0].getAttribute('href'), '/c/42/5..10/glados.txt');
+      assert.isFalse(linkEls[1].hasAttribute('href'));
+      element._path = 'chell.go';
+      flushAsynchronousOperations();
+      assert.isFalse(linkEls[0].hasAttribute('href'));
+      assert.equal(linkEls[1].getAttribute('href'), '/c/42/5..10/glados.txt');
+    });
+
     test('file review status', function(done) {
       element._loggedIn = true;
       element._changeNum = '42';