fixup next-button tests, prove #3686 fixed

tests/toolbar/next-button.js

@@ -8,8 +8,7 @@ SEE ALSO:
 describe('next button', function() {
 	pushOptions({
 		defaultView: 'agendaWeek',
-		defaultDate: '2017-06-08',
-		dateIncrement: { years: 1 } // next range is 2018-06-03 - 2018-06-10
+		defaultDate: '2017-06-08'
 	});
 
 	describe('when there is no validRange', function() {
@@ -21,7 +20,8 @@ describe('next button', function() {
 
 	describe('when next date range is completely within validRange', function() {
 		pushOptions({
-			validRange: { end: '2018-06-10' }
+			validRange: { end: '2018-06-10' },
+			dateIncrement: { years: 1 } // next range is 2018-06-03 - 2018-06-10
 		});
 		it('is enabled', function() {
 			initCalendar();
@@ -31,7 +31,8 @@ describe('next button', function() {
 
 	describe('when next date range is partially outside validRange', function() {
 		pushOptions({
-			validRange: { end: '2018-06-05' }
+			validRange: { end: '2018-06-05' },
+			dateIncrement: { years: 1 } // next range is 2018-06-03 - 2018-06-10
 		});
 		it('is enabled', function() {
 			initCalendar();
@@ -41,7 +42,8 @@ describe('next button', function() {
 
 	describe('when next date range is completely beyond validRange', function() {
 		pushOptions({
-			validRange: { end: '2018-06-03' }
+			validRange: { end: '2018-06-03' },
+			dateIncrement: { years: 1 } // next range is 2018-06-03 - 2018-06-10
 		});
 		it('is disabled', function() {
 			initCalendar();
@@ -53,7 +55,20 @@ describe('next button', function() {
 		pushOptions({
 			defaultDate: '2017-03-31',
 			defaultView: 'basicDay',
-			weekends: false
+			weekends: false,
+			dateIncrement: { years: 1 } // next range is 2018-06-03 - 2018-06-10
+		});
+		it('is enabled', function() {
+			initCalendar();
+			ToolbarUtils.expectButtonEnabled('next', true);
+		});
+	});
+
+	describe('when defaultDate is constrained forward to validRange and next week is valid', function() {
+		pushOptions({
+			defaultDate: '2017-07-17',
+			defaultView: 'agendaWeek',
+			validRange: { start: '2036-05-03', end: '2036-06-01' }
 		});
 		it('is enabled', function() {
 			initCalendar();